C語言庫函式及示例

函式名: abort
功能: 異常終止一個程式
用法: void abort(void);
程式例:
#include <stdio.h>
#include <stdlib.h>
int main(void)
{
printf("Calling abort()n");
abort();
return 0; /* This is never reached */
}

函式名: abs
功能: 求整數的絕對值
用法: int abs(int i);
程式例:
#include <stdio.h>
#include <math.h>

int main(void)
{
int number = -1234;

printf("number: %d absolute value: %dn", number, abs(number));
return 0;
}

函式名: absread, abswirte
功能: 絕對磁碟扇區讀、寫資料
用法: int absread(int drive, int nsects, int sectno, void *buffer);
int abswrite(int drive, int nsects, in tsectno, void *buffer);
程式例:
/* absread example */

#include <stdio.h>
#include <conio.h>
#include <process.h>
#include <dos.h>

int main(void)
{
int i, strt, ch_out, sector;
char buf[512];

printf("Insert a diskette into drive A and press any keyn");
getch();
sector = 0;
if (absread(0, 1, sector, &buf) != 0)
{
perror("Disk problem");
exit(1);
}
printf("Read OKn");
strt = 3;
for (i=0; i<80; i++)
{
ch_out = buf[strt+i];
putchar(ch_out);
}
printf("n");
return(0);
}

函式名: access
功能: 確定檔案的訪問許可權
用法: int access(const char *filename, int amode);
程式例:
#include <stdio.h>
#include <io.h>

int file_exists(char *filename);

int main(void)
{
printf("Does NOTEXIST.FIL exist: %sn",
file_exists("NOTEXISTS.FIL") ? "YES" : "NO");
return 0;
}

int file_exists(char *filename)
{
return (access(filename, 0) == 0);
}

函式名: acos
功能: 反餘弦函式
用法: double acos(double x);
程式例:
#include <stdio.h>
#include <math.h>

int main(void)
{
double result;
double x = 0.5;

result = acos(x);
printf("The arc cosine of %lf is %lfn", x, result);
return 0;
}

函式名: allocmem
功能: 分配DOS儲存段
用法: int allocmem(unsigned size, unsigned *seg);
程式例:
#include <dos.h>
#include <alloc.h>
#include <stdio.h>

int main(void)
{
unsigned int size, segp;
int stat;

size = 64; /* (64 x 16) = 1024 bytes */
stat = allocmem(size, &segp);
if (stat == -1)
printf("Allocated memory at segment: %xn", segp);
else
printf("Failed: maximum number of paragraphs available is %un",
stat);

return 0;
}

函式名: arc
功能: 畫一弧線
用法: void far arc(int x, int y, int stangle, int endangle, int radius);
程式例:
#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int midx, midy;
int stangle = 45, endangle = 135;
int radius = 100;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult(); /* an error occurred */
if (errorcode != grOk)
{
printf("Graphics error: %sn", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();

exit(1); /* terminate with an error code */
}

midx = getmaxx() / 2;
midy = getmaxy() / 2;
setcolor(getmaxcolor());

/* draw arc */
arc(midx, midy, stangle, endangle, radius);

/* clean up */
getch();
closegraph();
return 0;
}

函式名: asctime
功能: 轉換日期和時間為ASCII碼
用法: char *asctime(const struct tm *tblock);
程式例:
#include <stdio.h>
#include <string.h>
#include <time.h>

int main(void)
{
struct tm t;
char str[80];

/* sample loading of tm structure */

t.tm_sec = 1; /* Seconds */
t.tm_min = 30; /* Minutes */
t.tm_hour = 9; /* Hour */
t.tm_mday = 22; /* Day of the Month */
t.tm_mon = 11; /* Month */
t.tm_year = 56; /* Year - does not include century */
t.tm_wday = 4; /* Day of the week */
t.tm_yday = 0; /* Does not show in asctime */
t.tm_isdst = 0; /* Is Daylight SavTime; does not show in asctime */

/* converts structure to null terminated
string */

strcpy(str, asctime(&t));
printf("%sn", str);

return 0;
}

函式名: asin
功能: 反正弦函式
用法: double asin(double x);
程式例:
#include <stdio.h>
#include <math.h>

int main(void)
{
double result;
double x = 0.5;

result = asin(x);
printf("The arc sin of %lf is %lfn", x, result);
return(0);
}

函式名: assert
功能: 測試一個條件並可能使程式終止
用法: void assert(int test);
程式例:
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>

struct ITEM {
int key;
int value;
};

/* add item to list, make sure list is not null */
void additem(struct ITEM *itemptr) {
assert(itemptr != NULL);
/* add item to list */
}

int main(void)
{
additem(NULL);
return 0;
}

函式名: atan
功能: 反正切函式
用法: double atan(double x);
程式例:
#include <stdio.h>
#include <math.h>

int main(void)
{
double result;
double x = 0.5;

result = atan(x);
printf("The arc tangent of %lf is %lfn", x, result);
return(0);
}

函式名: atan2
功能: 計算Y/X的反正切值
用法: double atan2(double y, double x);
程式例:
#include <stdio.h>
#include <math.h>

int main(void)
{
double result;
double x = 90.0, y = 45.0;

result = atan2(y, x);
printf("The arc tangent ratio of %lf is %lfn", (y / x), result);
return 0;
}

函式名: atexit
功能: 註冊終止函式
用法: int atexit(atexit_t func);
程式例:
#include <stdio.h>
#include <stdlib.h>

void exit_fn1(void)
{
printf("Exit function #1 calledn");
}

void exit_fn2(void)
{
printf("Exit function #2 calledn");
}

int main(void)
{
/* post exit function #1 */
atexit(exit_fn1);
/* post exit function #2 */
atexit(exit_fn2);
return 0;
}

函式名: atof
功能: 把字串轉換成浮點數
用法: double atof(const char *nptr);
程式例:
#include <stdlib.h>
#include <stdio.h>

int main(void)
{
float f;
char *str = "12345.67";

f = atof(str);
printf("string = %s float = %fn", str, f);
return 0;
}

函式名: atoi
功能: 把字串轉換成長整型數
用法: int atoi(const char *nptr);
程式例:
#include <stdlib.h>
#include <stdio.h>

int main(void)
{
int n;
char *str = "12345.67";

n = atoi(str);
printf("string = %s integer = %dn", str, n);
return 0;
}

函式名: atol
功能: 把字串轉換成長整型數
用法: long atol(const char *nptr);
程式例:

#include <stdlib.h>
#include <stdio.h>

int main(void)
{
long l;
char *str = "98765432";

l = atol(lstr);
printf("string = %s integer = %ldn", str, l);
return(0);
}

函式名: bar
功能: 畫一個二維條形圖
用法: void far bar(int left, int top, int right, int bottom);
程式例:
#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int midx, midy, i;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

midx = getmaxx() / 2;
midy = getmaxy() / 2;

/* loop through the fill patterns */
for (i=SOLID_FILL; i<USER_FILL; i++)
{
/* set the fill style */
setfillstyle(i, getmaxcolor());

/* draw the bar */
bar(midx-50, midy-50, midx+50,
midy+50);

getch();
}

/* clean up */
closegraph();
return 0;
}

函式名: bar3d
功能: 畫一個三維條形圖
用法: void far bar3d(int left, int top, int right, int bottom,
int depth, int topflag);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int midx, midy, i;

/* initialize graphics, local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with error code */
}

midx = getmaxx() / 2;
midy = getmaxy() / 2;

/* loop through the fill patterns */
for (i=EMPTY_FILL; i<USER_FILL; i++)
{
/* set the fill style */
setfillstyle(i, getmaxcolor());

/* draw the 3-d bar */
bar3d(midx-50, midy-50, midx+50, midy+50, 10, 1);

getch();
}

/* clean up */
closegraph();
return 0;
}

函式名: bdos
功能: DOS系統呼叫
用法: int bdos(int dosfun, unsigned dosdx, unsigned dosal);
程式例:

#include <stdio.h>
#include <dos.h>

/* Get current drive as 'A', 'B', ... */
char current_drive(void)
{
char curdrive;

/* Get current disk as 0, 1, ... */
curdrive = bdos(0x19, 0, 0);
return('A' + curdrive);
}

int main(void)
{
printf("The current drive is %c:\n", current_drive());
return 0;
}

函式名: bdosptr
功能: DOS系統呼叫
用法: int bdosptr(int dosfun, void *argument, unsigned dosal);
程式例:

#include <string.h>
#include <stdio.h>
#include <dir.h>
#include <dos.h>
#include <errno.h>
#include <stdlib.h>

#define BUFLEN 80

int main(void)
{
char buffer[BUFLEN];
int test;

printf("Enter full pathname of a directory\n");
gets(buffer);

test = bdosptr(0x3B,buffer,0);
if(test)
{
printf("DOS error message: %d\n", errno);
/* See errno.h for error listings */
exit (1);
}

getcwd(buffer, BUFLEN);
printf("The current directory is: %s\n", buffer);

return 0;
}

函式名: bioscom
功能: 序列I/O通訊
用法: int bioscom(int cmd, char abyte, int port);
程式例:

#include <bios.h>
#include <conio.h>

#define COM1 0
#define DATA_READY 0x100
#define TRUE 1
#define FALSE 0

#define SETTINGS ( 0x80 | 0x02 | 0x00 | 0x00)

int main(void)
{
int in, out, status, DONE = FALSE;

bioscom(0, SETTINGS, COM1);
cprintf("... BIOSCOM [ESC] to exit ...\n");
while (!DONE)
{
status = bioscom(3, 0, COM1);
if (status & DATA_READY)
if ((out = bioscom(2, 0, COM1) & 0x7F) != 0)
putch(out);
if (kbhit())
{
if ((in = getch()) == '\x1B')
DONE = TRUE;
bioscom(1, in, COM1);
}
}
return 0;
}

函式名: biosdisk
功能: 軟硬碟I/O
用法: int biosdisk(int cmd, int drive, int head, int track, int sector
int nsects, void *buffer);
程式例:

#include <bios.h>
#include <stdio.h>

int main(void)
{
int result;
char buffer[512];

printf("Testing to see if drive a: is ready\n");
result = biosdisk(4,0,0,0,0,1,buffer);
result &= 0x02;
(result) ? (printf("Drive A: Ready\n")) :
(printf("Drive A: Not Ready\n"));

return 0;
}

函式名: biosequip
功能: 檢查裝置
用法: int biosequip(void);
程式例:

#include <bios.h>
#include <stdio.h>

int main(void)
{
int result;
char buffer[512];

printf("Testing to see if drive a: is ready\n");
result = biosdisk(4,0,0,0,0,1,buffer);
result &= 0x02;
(result) ? (printf("Drive A: Ready\n")) :
(printf("Drive A: Not Ready\n"));

return 0;
}

函式名: bioskey
功能: 直接使用BIOS服務的鍵盤介面
用法: int bioskey(int cmd);
程式例:

#include <stdio.h>
#include <bios.h>
#include <ctype.h>

#define RIGHT 0x01
#define LEFT 0x02
#define CTRL 0x04
#define ALT 0x08

int main(void)
{
int key, modifiers;

/* function 1 returns 0 until a key is pressed */
while (bioskey(1) == 0);

/* function 0 returns the key that is waiting */
key = bioskey(0);

/* use function 2 to determine if shift keys were used */
modifiers = bioskey(2);
if (modifiers)
{
printf("[");
if (modifiers & RIGHT) printf("RIGHT");
if (modifiers & LEFT) printf("LEFT");
if (modifiers & CTRL) printf("CTRL");
if (modifiers & ALT) printf("ALT");
printf("]");
}
/* print out the character read */
if (isalnum(key & 0xFF))
printf("'%c'\n", key);
else
printf("%#02x\n", key);
return 0;
}

函式名: biosmemory
功能: 返回儲存塊大小
用法:int biosmemory(void);
程式例:

#include <stdio.h>
#include <bios.h>

int main(void)
{
int memory_size;

memory_size = biosmemory(); /* returns value up to 640K */
printf("RAM size = %dK\n",memory_size);
return 0;
}

函式名: biosprint
功能: 直接使用BIOS服務的印表機I/O
用法: int biosprint(int cmd, int byte, int port);
程式例:

#include <stdio.h>
#include <conio.h>
#include <bios.h>

int main(void)
{
#define STATUS 2 /* printer status command */
#define PORTNUM 0 /* port number for LPT1 */

int status, abyte=0;

printf("Please turn off your printer. Press any key to continue\n");
getch();
status = biosprint(STATUS, abyte, PORTNUM);
if (status & 0x01)
printf("Device time out.\n");
if (status & 0x08)
printf("I/O error.\n");

if (status & 0x10)
printf("Selected.\n");
if (status & 0x20)
printf("Out of paper.\n");

if (status & 0x40)
printf("Acknowledge.\n");
if (status & 0x80)
printf("Not busy.\n");

return 0;
}

函式名: biostime
功能: 讀取或設定BIOS時間
用法: long biostime(int cmd, long newtime);
程式例:

#include <stdio.h>
#include <bios.h>
#include <time.h>
#include <conio.h>

int main(void)
{
long bios_time;

clrscr();
cprintf("The number of clock ticks since midnight is:\r\n");
cprintf("The number of seconds since midnight is:\r\n");
cprintf("The number of minutes since midnight is:\r\n");
cprintf("The number of hours since midnight is:\r\n");
cprintf("\r\nPress any key to quit:");
while(!kbhit())
{
bios_time = biostime(0, 0L);

gotoxy(50, 1);
cprintf("%lu", bios_time);

gotoxy(50, 2);
cprintf("%.4f", bios_time / CLK_TCK);

gotoxy(50, 3);
cprintf("%.4f", bios_time / CLK_TCK / 60);

gotoxy(50, 4);
cprintf("%.4f", bios_time / CLK_TCK / 3600);
}
return 0;
}

函式名: brk
功能: 改變資料段空間分配
用法: int brk(void *endds);
程式例:

#include <stdio.h>
#include <alloc.h>

int main(void)
{
char *ptr;

printf("Changing allocation with brk()\n");
ptr = malloc(1);
printf("Before brk() call: %lu bytes free\n", coreleft());
brk(ptr+1000);
printf(" After brk() call: %lu bytes free\n", coreleft());
return 0;
}

函式名: bsearch
功能: 二分法搜尋
用法: void *bsearch(const void *key, const void *base, size_t *nelem,
size_t width, int(*fcmp)(const void *, const *));
程式例:

#include <stdlib.h>
#include <stdio.h>

#define NELEMS(arr) (sizeof(arr) / sizeof(arr[0]))

int numarray[] = {123, 145, 512, 627, 800, 933};

int numeric (const int *p1, const int *p2)
{
return(*p1 - *p2);
}

int lookup(int key)
{
int *itemptr;

/* The cast of (int(*)(const void *,const void*))
is needed to avoid a type mismatch error at
compile time */
itemptr = bsearch (&key, numarray, NELEMS(numarray),
sizeof(int), (int(*)(const void *,const void *))numeric);
return (itemptr != NULL);
}

int main(void)
{
if (lookup(512))
printf("512 is in the table.\n");
else
printf("512 isn't in the table.\n");

return 0;
}
函式名: cabs
功能: 計算複數的絕對值
用法: double cabs(struct complex z);
程式例:
#include <stdio.h>
#include <math.h>

int main(void)
{
struct complex z;
double val;

z.x = 2.0;
z.y = 1.0;
val = cabs(z);

printf("The absolute value of %.2lfi %.2lfj is %.2lf", z.x, z.y, val);
return 0;
}

函式名: calloc
功能: 分配主儲存器
用法: void *calloc(size_t nelem, size_t elsize);
程式例:

#include <stdio.h>
#include <alloc.h>

int main(void)
{
char *str = NULL;

/* allocate memory for string */
str = calloc(10, sizeof(char));

/* copy "Hello" into string */
strcpy(str, "Hello");

/* display string */
printf("String is %sn", str);

/* free memory */
free(str);

return 0;
}

函式名: ceil
功能: 向上舍入
用法: double ceil(double x);
程式例:

#include <math.h>
#include <stdio.h>

int main(void)
{
double number = 123.54;
double down, up;

down = floor(number);
up = ceil(number);

printf("original number %5.2lfn", number);
printf("number rounded down %5.2lfn", down);
printf("number rounded up %5.2lfn", up);

return 0;
}

函式名: cgets
功能: 從控制檯讀字串
用法: char *cgets(char *str);
程式例:

#include <stdio.h>
#include <conio.h>

int main(void)
{
char buffer[83];
char *p;

/* There''s space for 80 characters plus the NULL terminator */
buffer[0] = 81;

printf("Input some chars:");
p = cgets(buffer);
printf("ncgets read %d characters: "%s"n", buffer[1], p);
printf("The returned pointer is %p, buffer[0] is at %pn", p, &buffer);

/* Leave room for 5 characters plus the NULL terminator */
buffer[0] = 6;

printf("Input some chars:");
p = cgets(buffer);
printf("ncgets read %d characters: "%s"n", buffer[1], p);
printf("The returned pointer is %p, buffer[0] is at %pn", p, &buffer);
return 0;
}

函式名: chdir
功能: 改變工作目錄
用法: int chdir(const char *path);
程式例:

#include <stdio.h>
#include <stdlib.h>
#include <dir.h>

char old_dir[MAXDIR];
char new_dir[MAXDIR];

int main(void)
{
if (getcurdir(0, old_dir))
{
perror("getcurdir()");
exit(1);
}
printf("Current directory is: %sn", old_dir);

if (chdir(""))
{
perror("chdir()");
exit(1);
}

if (getcurdir(0, new_dir))
{
perror("getcurdir()");
exit(1);
}
printf("Current directory is now: %sn", new_dir);

printf("nChanging back to orignal directory: %sn", old_dir);
if (chdir(old_dir))
{
perror("chdir()");
exit(1);
}

return 0;
}

函式名: _chmod, chmod
功能: 改變檔案的訪問方式
用法: int chmod(const char *filename, int permiss);
程式例:

#include <sysstat.h>
#include <stdio.h>
#include <io.h>

void make_read_only(char *filename);

int main(void)
{
make_read_only("NOTEXIST.FIL");
make_read_only("MYFILE.FIL");
return 0;
}

void make_read_only(char *filename)
{
int stat;

stat = chmod(filename, S_IREAD);
if (stat)
printf("Couldn''t make %s read-onlyn", filename);
else
printf("Made %s read-onlyn", filename);
}

函式名: chsize
功能: 改變檔案大小
用法: int chsize(int handle, long size);
程式例:

#include <string.h>
#include <fcntl.h>
#include <io.h>

int main(void)
{
int handle;
char buf[11] = "0123456789";

/* create text file containing 10 bytes */
handle = open("DUMMY.FIL", O_CREAT);
write(handle, buf, strlen(buf));

/* truncate the file to 5 bytes in size */
chsize(handle, 5);

/* close the file */
close(handle);
return 0;
}

函式名: circle
功能: 在給定半徑以(x, y)為圓心畫圓
用法: void far circle(int x, int y, int radius);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int midx, midy;
int radius = 100;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %sn", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

midx = getmaxx() / 2;
midy = getmaxy() / 2;
setcolor(getmaxcolor());

/* draw the circle */
circle(midx, midy, radius);

/* clean up */
getch();
closegraph();
return 0;
}

函式名: cleardevice
功能: 清除圖形螢幕
用法: void far cleardevice(void);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int midx, midy;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %sn", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

midx = getmaxx() / 2;
midy = getmaxy() / 2;
setcolor(getmaxcolor());

/* for centering screen messages */
settextjustify(CENTER_TEXT, CENTER_TEXT);

/* output a message to the screen */
outtextxy(midx, midy, "press any key to clear the screen:");

/* wait for a key */
getch();

/* clear the screen */
cleardevice();

/* output another message */
outtextxy(midx, midy, "press any key to quit:");

/* clean up */
getch();
closegraph();
return 0;
}

函式名: clearerr
功能: 復位錯誤標誌
用法:void clearerr(FILE *stream);
程式例:

#include <stdio.h>

int main(void)
{
FILE *fp;
char ch;

/* open a file for writing */
fp = fopen("DUMMY.FIL", "w");

/* force an error condition by attempting to read */
ch = fgetc(fp);
printf("%cn",ch);

if (ferror(fp))
{
/* display an error message */
printf("Error reading from DUMMY.FILn");

/* reset the error and EOF indicators */
clearerr(fp);
}

fclose(fp);
return 0;
}

函式名: clearviewport
功能: 清除圖形視區
用法: void far clearviewport(void);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

#define CLIP_ON 1 /* activates clipping in viewport */

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int ht;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %sn", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

setcolor(getmaxcolor());
ht = textheight("W");

/* message in default full-screen viewport */
outtextxy(0, 0, "* <-- (0, 0) in default viewport");

/* create a smaller viewport */
setviewport(50, 50, getmaxx()-50, getmaxy()-50, CLIP_ON);

/* display some messages */
outtextxy(0, 0, "* <-- (0, 0) in smaller viewport");
outtextxy(0, 2*ht, "Press any key to clear viewport:");

/* wait for a key */
getch();

/* clear the viewport */
clearviewport();

/* output another message */
outtextxy(0, 0, "Press any key to quit:");

/* clean up */
getch();
closegraph();
return 0;
}

函式名: _close, close
功能: 關閉檔案控制程式碼
用法: int close(int handle);
程式例:

#include <string.h>
#include <stdio.h>
#include <fcntl.h>
#include <io.h>

main()
{
int handle;
char buf[11] = "0123456789";

/* create a file containing 10 bytes */
handle = open("NEW.FIL", O_CREAT);
if (handle > -1)
{
write(handle, buf, strlen(buf));

/* close the file */
close(handle);
}
else
{
printf("Error opening filen");
}
return 0;
}

函式名: clock
功能: 確定處理器時間
用法: clock_t clock(void);
程式例:

#include <time.h>
#include <stdio.h>
#include <dos.h>

int main(void)
{
clock_t start, end;
start = clock();

delay(2000);

end = clock();
printf("The time was: %fn", (end - start) / CLK_TCK);

return 0;
}

函式名: closegraph
功能: 關閉圖形系統
用法: void far closegraph(void);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int x, y;

/* initialize graphics mode */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();

if (errorcode != grOk) /* an error
occurred */
{
printf("Graphics error: %sn", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

x = getmaxx() / 2;
y = getmaxy() / 2;

/* output a message */
settextjustify(CENTER_TEXT, CENTER_TEXT);
outtextxy(x, y, "Press a key to close the graphics system:");

/* wait for a key */
getch();

/* closes down the graphics system */
closegraph();

printf("We''re now back in text mode.n");
printf("Press any key to halt:");
getch();
return 0;
}

函式名: clreol
功能: 在文字視窗中清除字元到行末
用法: void clreol(void);
程式例:

#include <conio.h>

int main(void)

{
clrscr();
cprintf("The function CLREOL clears all characters from thern");
cprintf("cursor position to the end of the line within thern");
cprintf("current text window, without moving the cursor.rn");
cprintf("Press any key to continue . . .");
gotoxy(14, 4);
getch();

clreol();
getch();

return 0;
}

函式名: clrscr
功能: 清除文字模式視窗
用法: void clrscr(void);
程式例:

#include <conio.h>

int main(void)
{
int i;

clrscr();
for (i = 0; i < 20; i++)
cprintf("%drn", i);
cprintf("rnPress any key to clear screen");
getch();

clrscr();
cprintf("The screen has been cleared!");
getch();

return 0;
}

函式名: coreleft
功能: 返回未使用記憶體的大小
用法: unsigned coreleft(void);
程式例:

#include <stdio.h>
#include <alloc.h>

int main(void)
{
printf("The difference between the highest allocated block andn");
printf("the top of the heap is: %lu bytesn", (unsigned long) coreleft());

return 0;
}

函式名: cos
功能: 餘弦函式
用法: double cos(double x);
程式例:

#include <stdio.h>
#include <math.h>

int main(void)
{
double result;
double x = 0.5;

result = cos(x);
printf("The cosine of %lf is %lfn", x, result);
return 0;
}

函式名: cosh
功能: 雙曲餘弦函式
用法: dluble cosh(double x);
程式例:

#include <stdio.h>
#include <math.h>

int main(void)
{
double result;
double x = 0.5;

result = cosh(x);
printf("The hyperboic cosine of %lf is %lfn", x, result);
return 0;
}
函式名: country
功能: 返回與國家有關的資訊
用法: struct COUNTRY *country(int countrycode, struct country *country);
程式例:

#include <dos.h>
#include <stdio.h>

#define USA 0

int main(void)
{
struct COUNTRY country_info;

country(USA, &country_info);
printf("The currency symbol for the USA is: %sn",
country_info.co_curr);
return 0;
}

函式名: cprintf
功能: 送格式化輸出至螢幕
用法: int cprintf(const char *format[, argument, ...]);
程式例:

#include <conio.h>

int main(void)
{
/* clear the screen */
clrscr();

/* create a text window */
window(10, 10, 80, 25);

/* output some text in the window */
cprintf("Hello worldrn");

/* wait for a key */
getch();
return 0;
}

函式名: cputs
功能: 寫字元到螢幕
用法: void cputs(const char *string);
程式例:

#include <conio.h>

int main(void)
{
/* clear the screen */
clrscr();

/* create a text window */
window(10, 10, 80, 25);

/* output some text in the window */
cputs("This is within the windowrn");

/* wait for a key */
getch();
return 0;
}

函式名: _creat creat
功能: 建立一個新檔案或重寫一個已存在的檔案
用法: int creat (const char *filename, int permiss);
程式例:

#include <sysstat.h>
#include <string.h>
#include <fcntl.h>
#include <io.h>

int main(void)
{
int handle;
char buf[11] = "0123456789";

/* change the default file mode from text to binary */
_fmode = O_BINARY;

/* create a binary file for reading and writing */
handle = creat("DUMMY.FIL", S_IREAD S_IWRITE);

/* write 10 bytes to the file */
write(handle, buf, strlen(buf));

/* close the file */
close(handle);
return 0;
}

函式名: creatnew
功能: 建立一個新檔案
用法: int creatnew(const char *filename, int attrib);
程式例:

#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <dos.h>
#include <io.h>

int main(void)
{
int handle;
char buf[11] = "0123456789";

/* attempt to create a file that doesn''t already exist */
handle = creatnew("DUMMY.FIL", 0);

if (handle == -1)
printf("DUMMY.FIL already exists.n");
else
{
printf("DUMMY.FIL successfully created.n");
write(handle, buf, strlen(buf));
close(handle);
}
return 0;
}

函式名: creattemp
功能: 建立一個新檔案或重寫一個已存在的檔案
用法: int creattemp(const char *filename, int attrib);
程式例:

#include <string.h>
#include <stdio.h>
#include <io.h>

int main(void)
{
int handle;
char pathname[128];

strcpy(pathname, "");

/* create a unique file in the root directory */
handle = creattemp(pathname, 0);

printf("%s was the unique file created.n", pathname);
close(handle);
return 0;
}

函式名: cscanf
功能: 從控制檯執行格式化輸入
用法: int cscanf(char *format[,argument, ...]);
程式例:

#include <conio.h>

int main(void)
{
char string[80];

/* clear the screen */
clrscr();

/* Prompt the user for input */
cprintf("Enter a string with no spaces:");

/* read the input */
cscanf("%s", string);

/* display what was read */
cprintf("rnThe string entered is: %s", string);
return 0;
}

函式名: ctime
功能: 把日期和時間轉換為字串
用法: char *ctime(const time_t *time);
程式例:

#include <stdio.h>
#include <time.h>

int main(void)
{
time_t t;

time(&t);
printf("Today''s date and time: %sn", ctime(&t));
return 0;
}

函式名: ctrlbrk
功能: 設定Ctrl-Break處理程式
用法: void ctrlbrk(*fptr)(void);
程式例:

#include <stdio.h>
#include <dos.h>

#define ABORT 0

int c_break(void)
{
printf("Control-Break pressed. Program aborting ...n");
return (ABORT);
}

int main(void)
{
ctrlbrk(c_break);
for(;;)
{
printf("Looping... Press <Ctrl-Break> to quit:n");
}
return 0;
}

函式名: delay
功能: 將程式的執行暫停一段時間(毫秒)
用法: void delay(unsigned milliseconds);
程式例:
/* Emits a 440-Hz tone for 500 milliseconds */
#include <dos.h>
int main(void)
{
sound(440);
delay(500);
nosound();

return 0;
}

函式名: delline
功能: 在文字視窗中刪去一行
用法: void delline(void);
程式例:

#include <conio.h>

int main(void)
{
clrscr();
cprintf("The function DELLINE deletes \
the line containing the\r\n");
cprintf("cursor and moves all lines \
below it one line up.\r\n");
cprintf("DELLINE operates within the \
currently active text\r\n");
cprintf("window. Press any key to \
continue . . .");
gotoxy(1,2); /* Move the cursor to the
second line and first column */
getch();

delline();
getch();

return 0;
}

函式名: detectgraph
功能: 通過檢測硬體確定圖形驅動程式和模式
用法: void far detectgraph(int far *graphdriver, int far *graphmode);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

/* names of the various cards supported */
char *dname[] = { "requests detection",
"a CGA",
"an MCGA",
"an EGA",
"a 64K EGA",
"a monochrome EGA",
"an IBM 8514",
"a Hercules monochrome",
"an AT&T 6300 PC",
"a VGA",
"an IBM 3270 PC"
};

int main(void)
{
/* returns detected hardware info. */
int gdriver, gmode, errorcode;

/* detect graphics hardware available */
detectgraph(&gdriver, &gmode);

/* read result of detectgraph call */
errorcode = graphresult();
if (errorcode != grOk) /* an error
occurred */
{
printf("Graphics error: %s\n", \
grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error
code */
}

/* display the information detected */
clrscr();
printf("You have %s video display \
card.\n", dname[gdriver]);
printf("Press any key to halt:");
getch();
return 0;
}

函式名: difftime
功能: 計算兩個時刻之間的時間差
用法: double difftime(time_t time2, time_t time1);
程式例:

#include <time.h>
#include <stdio.h>
#include <dos.h>
#include <conio.h>

int main(void)
{
time_t first, second;

clrscr();
first = time(NULL); /* Gets system
time */
delay(2000); /* Waits 2 secs */
second = time(NULL); /* Gets system time
again */

printf("The difference is: %f \
seconds\n",difftime(second,first));
getch();

return 0;
}

函式名: disable
功能: 遮蔽中斷
用法: void disable(void);
程式例:

/***NOTE: This is an interrupt service
routine. You cannot compile this program
with Test Stack Overflow turned on and
get an executable file that operates
correctly. */

#include <stdio.h>
#include <dos.h>
#include <conio.h>

#define INTR 0X1C /* The clock tick
interrupt */

void interrupt ( *oldhandler)(void);

int count=0;

void interrupt handler(void)
{
/* disable interrupts during the handling of
the interrupt */
disable();
/* increase the global counter */
count++;
/* reenable interrupts at the end of the
handler */
enable();
/* call the old routine */
oldhandler();
}

int main(void)
{
/* save the old interrupt vector */
oldhandler = getvect(INTR);

/* install the new interrupt handler */
setvect(INTR, handler);

/* loop until the counter exceeds 20 */
while (count < 20)
printf("count is %d\n",count);

/* reset the old interrupt handler */
setvect(INTR, oldhandler);

return 0;
}

函式名: div
功能: 將兩個整數相除, 返回商和餘數
用法: div_t (int number, int denom);
程式例:

#include <stdlib.h>
#include <stdio.h>

div_t x;

int main(void)
{
x = div(10,3);
printf("10 div 3 = %d remainder %d\n", x.quot, x.rem);

return 0;
}

函式名: dosexterr
功能: 獲取擴充套件DOS錯誤資訊
用法: int dosexterr(struct DOSERR *dblkp);
程式例:

#include <stdio.h>
#include <dos.h>

int main(void)
{
FILE *fp;
struct DOSERROR info;

fp = fopen("perror.dat","r");
if (!fp) perror("Unable to open file for
reading");
dosexterr(&info);

printf("Extended DOS error \
information:\n");
printf(" Extended error: \
%d\n",info.exterror);
printf(" Class: \
%x\n",info.class);
printf(" Action: \
%x\n",info.action);
printf(" Error Locus: \
%x\n",info.locus);

return 0;
}

函式名: dostounix
功能: 轉換日期和時間為UNIX時間格式
用法: long dostounix(struct date *dateptr, struct time *timeptr);
程式例:

#include <time.h>
#include <stddef.h>
#include <dos.h>
#include <stdio.h>

int main(void)
{
time_t t;
struct time d_time;
struct date d_date;
struct tm *local;

getdate(&d_date);
gettime(&d_time);

t = dostounix(&d_date, &d_time);
local = localtime(&t);
printf("Time and Date: %s\n", \
asctime(local));

return 0;
}

函式名: drawpoly
功能: 畫多邊形
用法: void far drawpoly(int numpoints, int far *polypoints);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int maxx, maxy;

/* our polygon array */
int poly[10];

/* initialize graphics and local
variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk)
/* an error occurred */
{
printf("Graphics error: %s\n", \
grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
/* terminate with an error code */
exit(1);
}

maxx = getmaxx();
maxy = getmaxy();

poly[0] = 20; /* 1st vertext */
poly[1] = maxy / 2;

poly[2] = maxx - 20; /* 2nd */
poly[3] = 20;

poly[4] = maxx - 50; /* 3rd */
poly[5] = maxy - 20;

poly[6] = maxx / 2; /* 4th */
poly[7] = maxy / 2;
/*
drawpoly doesn't automatically close
the polygon, so we close it.
*/
poly[8] = poly[0];
poly[9] = poly[1];

/* draw the polygon */
drawpoly(5, poly);

/* clean up */
getch();
closegraph();
return 0;
}

函式名: dup
功能: 複製一個檔案控制程式碼
用法: int dup(int handle);
程式例:

#include <string.h>
#include <stdio.h>
#include <conio.h>
#include <io.h>

void flush(FILE *stream);

int main(void)
{
FILE *fp;
char msg[] = "This is a test";

/* create a file */
fp = fopen("DUMMY.FIL", "w");

/* write some data to the file */
fwrite(msg, strlen(msg), 1, fp);

clrscr();
printf("Press any key to flush \
DUMMY.FIL:");
getch();

/* flush the data to DUMMY.FIL without
closing it */
flush(fp);

printf("\nFile was flushed, Press any \
key to quit:");
getch();
return 0;
}

void flush(FILE *stream)
{
int duphandle;

/* flush TC's internal buffer */
fflush(stream);

/* make a duplicate file handle */
duphandle = dup(fileno(stream));

/* close the duplicate handle to flush the
DOS buffer */
close(duphandle);
}

函式名: dup2
功能: 複製檔案控制程式碼
用法: int dup2(int oldhandle, int newhandle);
程式例:

#include <sys\stat.h>
#include <string.h>
#include <fcntl.h>
#include <io.h>

int main(void)
{
#define STDOUT 1

int nul, oldstdout;
char msg[] = "This is a test";

/* create a file */
nul = open("DUMMY.FIL", O_CREAT | O_RDWR,
S_IREAD | S_IWRITE);

/* create a duplicate handle for standard
output */
oldstdout = dup(STDOUT);
/*
redirect standard output to DUMMY.FIL
by duplicating the file handle onto the
file handle for standard output.
*/
dup2(nul, STDOUT);

/* close the handle for DUMMY.FIL */
close(nul);

/* will be redirected into DUMMY.FIL */
write(STDOUT, msg, strlen(msg));

/* restore original standard output
handle */
dup2(oldstdout, STDOUT);

/* close duplicate handle for STDOUT */
close(oldstdout);

return 0;
}
函式名: ecvt
功能: 把一個浮點數轉換為字串
用法: char ecvt(double value, int ndigit, int *decpt, int *sign);
程式例: #include <stdlib.h>
#include <stdio.h>
#include <conio.h> int main(void)
{
char *string;
double value;
int dec, sign;
int ndig = 10; clrscr();
value = 9.876;
string = ecvt(value, ndig, &dec, &sign);
printf("string = %s dec = %d \
sign = %d\n", string, dec, sign); value = -123.45;
ndig= 15;
string = ecvt(value,ndig,&dec,&sign);
printf("string = %s dec = %d sign = %d\n",
string, dec, sign);
value = 0.6789e5; /* scientific
notation */
ndig = 5;
string = ecvt(value,ndig,&dec,&sign);
printf("string = %s dec = %d\
sign = %d\n", string, dec, sign);
return 0;
} 函式名: ellipse
功能: 畫一橢圓
用法: void far ellipse(int x, int y, int stangle, int endangle,
int xradius, int yradius);
程式例: #include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h> int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int midx, midy;
int stangle = 0, endangle = 360;
int xradius = 100, yradius = 50; /* initialize graphics, local variables */
initgraph(&gdriver, &gmode, ""); /* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk)
/* an error occurred */
{
printf("Graphics error: %s\n",
grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1);
/* terminate with an error code */
}
midx = getmaxx() / 2;
midy = getmaxy() / 2;
setcolor(getmaxcolor()); /* draw ellipse */
ellipse(midx, midy, stangle, endangle,
xradius, yradius); /* clean up */
getch();
closegraph();
return 0;
} 函式名: enable
功能: 開放硬體中斷
用法: void enable(void);
程式例: /* ** NOTE:
This is an interrupt service routine. You can NOT compile this program
with Test Stack Overflow turned on and get an executable file which will
operate correctly.
*/ #include <stdio.h>
#include <dos.h>
#include <conio.h> /* The clock tick interrupt */
#define INTR 0X1C void interrupt ( *oldhandler)(void); int count=0; void interrupt handler(void)
{
/*
disable interrupts during the handling of the interrupt
*/
disable();
/* increase the global counter */
count++;
/*
re enable interrupts at the end of the handler
*/
enable();
/* call the old routine */
oldhandler();
}
int main(void)
{
/* save the old interrupt vector */
oldhandler = getvect(INTR); /* install the new interrupt handler */
setvect(INTR, handler); /* loop until the counter exceeds 20 */
while (count < 20)
printf("count is %d\n",count); /* reset the old interrupt handler */
setvect(INTR, oldhandler); return 0;
} 函式名: eof
功能: 檢測檔案結束
用法: int eof(int *handle);
程式例: #include <sys\stat.h>
#include <string.h>
#include <stdio.h>
#include <fcntl.h>
#include <io.h> int main(void)
{
int handle;
char msg[] = "This is a test";
char ch;
/* create a file */
handle = open("DUMMY.FIL",
O_CREAT O_RDWR,
S_IREAD S_IWRITE); /* write some data to the file */
write(handle, msg, strlen(msg)); /* seek to the beginning of the file */
lseek(handle, 0L, SEEK_SET); /*
reads chars from the file until hit EOF
*/
do
{
read(handle, &ch, 1);
printf("%c", ch);
} while (!eof(handle)); close(handle);
return 0;
} 函式名: exec...
功能: 裝入並執行其它程式的函式
用法: int execl(char *pathname, char *arg0, arg1, ..., argn, NULL);
int execle(char *pathname, char *arg0, arg1, ..., argn, NULL,
char *envp[]);
int execlp(char *pathname, char *arg0, arg1, .., NULL);
int execple(char *pathname, char *arg0, arg1, ..., NULL,
char *envp[]);
int execv(char *pathname, char *argv[]);
int execve(char *pathname, char *argv[], char *envp[]);
int execvp(char *pathname, char *argv[]);
int execvpe(char *pathname, char *argv[], char *envp[]);
程式例:
/* execv example */
#include <process.h>
#include <stdio.h>
#include <errno.h> void main(int argc, char *argv[])
{
int i; printf("Command line arguments:\n");
for (i=0; i<argc; i++)
printf("[%2d] : %s\n", i, argv[i]); printf("About to exec child with arg1 arg2 ...\n");
execv("CHILD.EXE", argv); perror("exec error"); exit(1);
} 函式名: exit
功能: 終止程式
用法: void exit(int status);
程式例: #include <stdlib.h>
#include <conio.h>
#include <stdio.h> int main(void)
{
int status; printf("Enter either 1 or 2\n");
status = getch();
/* Sets DOS errorlevel */
exit(status - '0');
/* Note: this line is never reached */
return 0;
} 函式名: eXP
功能: 指數函式
用法: double exp(double x);
程式例: #include <stdio.h>
#include <math.h> int main(void)
{
double result;
double x = 4.0; result = exp(x);
printf("'e' raised to the power \
of %lf (e ^ %lf) = %lf\n",
x, x, result); return 0;
}
函式名: fabs
功能: 返回浮點數的絕對值
用法: double fabs(double x);
程式例:
#include <stdio.h>
#include <math.h>

int main(void)
{
float number = -1234.0;

printf("number: %f absolute value: %f\n",
number, fabs(number));
return 0;
}

函式名: farcalloc
功能: 從遠堆疊中申請空間
用法: void far *farcalloc(unsigned long units, unsigned ling unitsz);
程式例:
#include <stdio.h>
#include <alloc.h>
#include <string.h>
#include <dos.h>

int main(void)
{
char far *fptr;
char *str = "Hello";

/* allocate memory for the far pointer */
fptr = farcalloc(10, sizeof(char));

/* copy "Hello" into allocated memory */
/*
Note: movedata is used because you
might be in a small data model, in
which case a normal string copy routine
can not be used since it assumes the
pointer size is near.
*/
movedata(FP_SEG(str), FP_OFF(str),
FP_SEG(fptr), FP_OFF(fptr),
strlen(str));

/* display string (note the F modifier) */
printf("Far string is: %Fs\n", fptr);

/* free the memory */
farfree(fptr);

return 0;
}

函式名: farcoreleft
功能: 返回遠堆中未作用儲存區大小
用法: long farcoreleft(void);
程式例:

#include <stdio.h>
#include <alloc.h>

int main(void)
{
printf("The difference between the\
highest allocated block in the\
far\n");
printf("heap and the top of the far heap\
is: %lu bytes\n", farcoreleft());

return 0;
}

函式名: farfree
功能: 從遠堆中釋放一塊
用法: void farfree(void);
程式例:

#include <stdio.h>
#include <alloc.h>
#include <string.h>
#include <dos.h>

int main(void)
{
char far *fptr;
char *str = "Hello";

/* allocate memory for the far pointer */
fptr = farcalloc(10, sizeof(char));

/* copy "Hello" into allocated memory */
/*
Note: movedata is used because you might be in a small data model,
in which case a normal string copy routine can't be used since it
assumes the pointer size is near.
*/
movedata(FP_SEG(str), FP_OFF(str),
FP_SEG(fptr), FP_OFF(fptr),
strlen(str));

/* display string (note the F modifier) */
printf("Far string is: %Fs\n", fptr);

/* free the memory */
farfree(fptr);

return 0;
}

函式名: farmalloc
功能: 從遠堆中分配儲存塊
用法: void far *farmalloc(unsigned long size);
程式例:

#include <stdio.h>
#include <alloc.h>
#include <string.h>
#include <dos.h>

int main(void)
{
char far *fptr;
char *str = "Hello";

/* allocate memory for the far pointer */
fptr = farmalloc(10);

/* copy "Hello" into allocated memory */
/*
Note: movedata is used because we might
be in a small data model, in which case
a normal string copy routine can not be
used since it assumes the pointer size
is near.
*/
movedata(FP_SEG(str), FP_OFF(str),
FP_SEG(fptr), FP_OFF(fptr),
strlen(str));

/* display string (note the F modifier) */
printf("Far string is: %Fs\n", fptr);

/* free the memory */
farfree(fptr);

return 0;
}

函式名: farrealloc
功能: 調整遠堆中的分配塊
用法: void far *farrealloc(void far *block, unsigned long newsize);
程式例:

#include <stdio.h>
#include <alloc.h>

int main(void)
{
char far *fptr;

fptr = farmalloc(10);
printf("First address: %Fp\n", fptr);
fptr = farrealloc(fptr,20);
printf("New address : %Fp\n", fptr);
farfree(fptr);
return 0;
}

函式名: fclose
功能: 關閉一個流
用法: int fclose(FILE *stream);
程式例:

#include <string.h>
#include <stdio.h>

int main(void)
{
FILE *fp;
char buf[11] = "0123456789";

/* create a file containing 10 bytes */
fp = fopen("DUMMY.FIL", "w");
fwrite(&buf, strlen(buf), 1, fp);

/* close the file */
fclose(fp);
return 0;
}

函式名: fcloseall
功能: 關閉開啟流
用法: int fcloseall(void);
程式例:

#include <stdio.h>

int main(void)
{
int streams_closed;

/* open two streams */
fopen("DUMMY.ONE", "w");
fopen("DUMMY.TWO", "w");

/* close the open streams */
streams_closed = fcloseall();

if (streams_closed == EOF)
/* issue an error message */
perror("Error");
else
/* print result of fcloseall() function */
printf("%d streams were closed.\n", streams_closed);

return 0;
}

函式名: fcvt
功能: 把一個浮點數轉換為字串
用法: char *fcvt(double value, int ndigit, int *decpt, int *sign);
程式例:

#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
char *string;
double value;
int dec, sign;
int ndig = 10;

clrscr();
value = 9.876;
string = ecvt(value, ndig, &dec, &sign);
printf("string = %s dec = %d \
sign = %d\n", string, dec, sign);

value = -123.45;
ndig= 15;
string = ecvt(value,ndig,&dec,&sign);
printf("string = %s dec = %d sign = %d\n",
string, dec, sign);

value = 0.6789e5; /* scientific
notation */
ndig = 5;
string = ecvt(value,ndig,&dec,&sign);
printf("string = %s dec = %d\
sign = %d\n", string, dec, sign);

return 0;
}

函式名: fdopen
功能: 把流與一個檔案控制程式碼相接
用法: FILE *fdopen(int handle, char *type);
程式例:

#include <sys\stat.h>
#include <stdio.h>
#include <fcntl.h>
#include <io.h>

int main(void)
{
int handle;
FILE *stream;

/* open a file */
handle = open("DUMMY.FIL", O_CREAT,
S_IREAD | S_IWRITE);

/* now turn the handle into a stream */
stream = fdopen(handle, "w");

if (stream == NULL)
printf("fdopen failed\n");
else
{
fprintf(stream, "Hello world\n");
fclose(stream);
}
return 0;
}

函式名: feof
功能: 檢測流上的檔案結束符
用法: int feof(FILE *stream);
程式例:

#include <stdio.h>

int main(void)
{
FILE *stream;

/* open a file for reading */
stream = fopen("DUMMY.FIL", "r");

/* read a character from the file */
fgetc(stream);

/* check for EOF */
if (feof(stream))
printf("We have reached end-of-file\n");

/* close the file */
fclose(stream);
return 0;
}

函式名: ferror
功能: 檢測流上的錯誤
用法: int ferror(FILE *stream);
程式例:

#include <stdio.h>

int main(void)
{
FILE *stream;

/* open a file for writing */
stream = fopen("DUMMY.FIL", "w");

/* force an error condition by attempting to read */
(void) getc(stream);

if (ferror(stream)) /* test for an error on the stream */
{
/* display an error message */
printf("Error reading from DUMMY.FIL\n");

/* reset the error and EOF indicators */
clearerr(stream);
}

fclose(stream);
return 0;
}

函式名: fflush
功能: 清除一個流
用法: int fflush(FILE *stream);
程式例:

#include <string.h>
#include <stdio.h>
#include <conio.h>
#include <io.h>

void flush(FILE *stream);

int main(void)
{
FILE *stream;
char msg[] = "This is a test";

/* create a file */
stream = fopen("DUMMY.FIL", "w");

/* write some data to the file */
fwrite(msg, strlen(msg), 1, stream);

clrscr();
printf("Press any key to flush\
DUMMY.FIL:");
getch();

/* flush the data to DUMMY.FIL without\
closing it */
flush(stream);

printf("\nFile was flushed, Press any key\
to quit:");
getch();
return 0;
}

void flush(FILE *stream)
{
int duphandle;

/* flush the stream's internal buffer */
fflush(stream);

/* make a duplicate file handle */
duphandle = dup(fileno(stream));

/* close the duplicate handle to flush\
the DOS buffer */
close(duphandle);
}

函式名: fgetc
功能: 從流中讀取字元
用法: int fgetc(FILE *stream);
程式例:

#include <string.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
FILE *stream;
char string[] = "This is a test";
char ch;

/* open a file for update */
stream = fopen("DUMMY.FIL", "w+");

/* write a string into the file */
fwrite(string, strlen(string), 1, stream);

/* seek to the beginning of the file */
fseek(stream, 0, SEEK_SET);

do
{
/* read a char from the file */
ch = fgetc(stream);

/* display the character */
putch(ch);
} while (ch != EOF);

fclose(stream);
return 0;
}

函式名: fgetchar
功能: 從流中讀取字元
用法: int fgetchar(void);
程式例:

#include <stdio.h>

int main(void)
{
char ch;

/* prompt the user for input */
printf("Enter a character followed by \
<Enter>: ");

/* read the character from stdin */
ch = fgetchar();

/* display what was read */
printf("The character read is: '%c'\n",
ch);
return 0;
}

函式名: fgetpos
功能: 取得當前檔案的控制程式碼
用法: int fgetpos(FILE *stream);
程式例:

#include <string.h>
#include <stdio.h>

int main(void)
{
FILE *stream;
char string[] = "This is a test";
fpos_t filepos;

/* open a file for update */
stream = fopen("DUMMY.FIL", "w+");

/* write a string into the file */
fwrite(string, strlen(string), 1, stream);

/* report the file pointer position */
fgetpos(stream, &filepos);
printf("The file pointer is at byte\
%ld\n", filepos);

fclose(stream);
return 0;
}

函式名: fgets
功能: 從流中讀取一字串
用法: char *fgets(char *string, int n, FILE *stream);
程式例:

#include <string.h>
#include <stdio.h>

int main(void)
{
FILE *stream;
char string[] = "This is a test";
char msg[20];

/* open a file for update */
stream = fopen("DUMMY.FIL", "w+");

/* write a string into the file */
fwrite(string, strlen(string), 1, stream);

/* seek to the start of the file */
fseek(stream, 0, SEEK_SET);

/* read a string from the file */
fgets(msg, strlen(string)+1, stream);

/* display the string */
printf("%s", msg);

fclose(stream);
return 0;
}

函式名: filelength
功能: 取檔案長度位元組數
用法: long filelength(int handle);
程式例:

#include <string.h>
#include <stdio.h>
#include <fcntl.h>
#include <io.h>

int main(void)
{
int handle;
char buf[11] = "0123456789";

/* create a file containing 10 bytes */
handle = open("DUMMY.FIL", O_CREAT);
write(handle, buf, strlen(buf));

/* display the size of the file */
printf("file length in bytes: %ld\n",
filelength(handle));

/* close the file */
close(handle);
return 0;
}

函式名: fillellipse
功能: 畫出並填充一橢圓
用法: void far fillellipse(int x, int y, int xradius, int yradius);
程式例:

#include <graphics.h>
#include <conio.h>

int main(void)
{
int gdriver = DETECT, gmode;
int xcenter, ycenter, i;

initgraph(&gdriver,&gmode,"");
xcenter = getmaxx() / 2;
ycenter = getmaxy() / 2;

for (i=0; i<13; i++)
{
setfillstyle(i,WHITE);
fillellipse(xcenter,ycenter,100,50);
getch();
}

closegraph();
return 0;
}
函式名: fillpoly
功能: 畫並填充一個多邊形
用法: void far fillpoly(int numpoints, int far *polypoints);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int i, maxx, maxy;

/* our polygon array */
int poly[8];

/* initialize graphics, local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk)
/* an error occurred */
{
printf("Graphics error: %s\n",
grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1);
/* terminate with an error code */
}

maxx = getmaxx();
maxy = getmaxy();

poly[0] = 20; /* 1st vertext */
poly[1] = maxy / 2;

poly[2] = maxx - 20; /* 2nd */
poly[3] = 20;

poly[4] = maxx - 50; /* 3rd */
poly[5] = maxy - 20;

/*
4th vertex. fillpoly automatically
closes the polygon.
*/
poly[6] = maxx / 2;
poly[7] = maxy / 2;

/* loop through the fill patterns */
for (i=EMPTY_FILL; i<USER_FILL; i++)
{
/* set fill pattern */
setfillstyle(i, getmaxcolor());

/* draw a filled polygon */
fillpoly(4, poly);

getch();
}

/* clean up */
closegraph();
return 0;
}

函式名: findfirst, findnext
功能: 搜尋磁碟目錄; 取得下一個匹配的findfirst模式的檔案
用法: int findfirst(char *pathname, struct ffblk *ffblk, int attrib);
int findnext(struct ffblk *ffblk);
程式例:

/* findnext example */

#include <stdio.h>
#include <dir.h>

int main(void)
{
struct ffblk ffblk;
int done;
printf("Directory listing of *.*\n");
done = findfirst("*.*",&ffblk,0);
while (!done)
{
printf(" %s\n", ffblk.ff_name);
done = findnext(&ffblk);
}

return 0;
}

函式名: floodfill
功能: 填充一個有界區域
用法: void far floodfill(int x, int y, int border);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int maxx, maxy;

/* initialize graphics, local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk)
/* an error occurred */
{
printf("Graphics error: %s\n",
grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1);
/* terminate with an error code */
}

maxx = getmaxx();
maxy = getmaxy();

/* select drawing color */
setcolor(getmaxcolor());

/* select fill color */
setfillstyle(SOLID_FILL, getmaxcolor());

/* draw a border around the screen */
rectangle(0, 0, maxx, maxy);

/* draw some circles */
circle(maxx / 3, maxy /2, 50);
circle(maxx / 2, 20, 100);
circle(maxx-20, maxy-50, 75);
circle(20, maxy-20, 25);

/* wait for a key */
getch();

/* fill in bounded region */
floodfill(2, 2, getmaxcolor());

/* clean up */
getch();
closegraph();
return 0;
}

函式名: floor
功能: 向下舍入
用法: double floor(double x);
程式例:

#include <stdio.h>
#include <math.h>

int main(void)
{
double number = 123.54;
double down, up;

down = floor(number);
up = ceil(number);

printf("original number %10.2lf\n",
number);
printf("number rounded down %10.2lf\n",
down);
printf("number rounded up %10.2lf\n",
up);

return 0;
}

函式名: flushall
功能: 清除所有緩衝區
用法: int flushall(void);
程式例:

#include <stdio.h>

int main(void)
{
FILE *stream;

/* create a file */
stream = fopen("DUMMY.FIL", "w");

/* flush all open streams */
printf("%d streams were flushed.\n",
flushall());

/* close the file */
fclose(stream);
return 0;
}

函式名: fmod
功能: 計算x對y的模, 即x/y的餘數
用法: double fmod(double x, double y);
程式例:

#include <stdio.h>
#include <math.h>

int main(void)
{
double x = 5.0, y = 2.0;
double result;

result = fmod(x,y);
printf("The remainder of (%lf / %lf) is \
%lf\n", x, y, result);
return 0;
}

函式名: fnmerge
功能: 建立新檔名
用法: void fnerge(char *path, char *drive, char *dir);
程式例:

#include <string.h>
#include <stdio.h>
#include <dir.h>

int main(void)
{
char s[MAXPATH];
char drive[MAXDRIVE];
char dir[MAXDIR];
char file[MAXFILE];
char ext[MAXEXT];

getcwd(s,MAXPATH); /* get the current working directory */
strcat(s,"\\"); /* append on a trailing \ character */
fnsplit(s,drive,dir,file,ext); /* split the string to separate elems */
strcpy(file,"DATA");
strcpy(ext,".TXT");
fnmerge(s,drive,dir,file,ext); /* merge everything into one string */
puts(s); /* display resulting string */

return 0;
}

函式名: fopen
功能: 開啟一個流
用法: FILE *fopen(char *filename, char *type);
程式例:

#include <stdlib.h>
#include <stdio.h>
#include <dir.h>

int main(void)
{
char *s;
char drive[MAXDRIVE];
char dir[MAXDIR];
char file[MAXFILE];
char ext[MAXEXT];
int flags;

s=getenv("COMSPEC"); /* get the comspec environment parameter */
flags=fnsplit(s,drive,dir,file,ext);

printf("Command processor info:\n");
if(flags & DRIVE)
printf("\tdrive: %s\n",drive);
if(flags & DIRECTORY)
printf("\tdirectory: %s\n",dir);
if(flags & FILENAME)
printf("\tfile: %s\n",file);
if(flags & EXTENSION)
printf("\textension: %s\n",ext);

return 0;
}

函式名: fprintf
功能: 傳送格式化輸出到一個流中
用法: int fprintf(FILE *stream, char *format[, argument,...]);
程式例:

/* Program to create backup of the
AUTOEXEC.BAT file */

#include <stdio.h>

int main(void)
{
FILE *in, *out;

if ((in = fopen("\\AUTOEXEC.BAT", "rt"))
== NULL)
{
fprintf(stderr, "Cannot open input \
file.\n");
return 1;
}

if ((out = fopen("\\AUTOEXEC.BAK", "wt"))
== NULL)
{
fprintf(stderr, "Cannot open output \
file.\n");
return 1;
}

while (!feof(in))
fputc(fgetc(in), out);

fclose(in);
fclose(out);
return 0;
}

函式名: FP_OFF
功能: 獲取遠地址偏移量
用法: unsigned FP_OFF(void far *farptr);
程式例:

/* FP_OFF */

#include <dos.h>
#include <stdio.h>

int main(void)
{
char *str = "fpoff.c";

printf("The offset of this file in memory\
is: %Fp\n", FP_OFF(str));

return 0;
}

函式名: FP_SEG
功能: 獲取遠地址段值
用法: unsigned FP_SEG(void far *farptr);
程式例:

/* FP_SEG */

#include <dos.h>
#include <stdio.h>

int main(void)
{
char *filename = "fpseg.c";

printf("The offset of this file in memory\
is: %Fp\n", FP_SEG(filename));

return(0);
}

函式名: fputc
功能: 送一個字元到一個流中
用法: int fputc(int ch, FILE *stream);
程式例:

#include <stdio.h>

int main(void)
{
char msg[] = "Hello world";
int i = 0;

while (msg[i])
{
fputc(msg[i], stdout);
i++;
}
return 0;
}

函式名: fputchar
功能: 送一個字元到標準輸出流(stdout)中
用法: int fputchar(char ch);
程式例:

#include <stdio.h>

int main(void)
{
char msg[] = "This is a test";
int i = 0;

while (msg[i])
{
fputchar(msg[i]);
i++;
}
return 0;
}

函式名: fputs
功能: 送一個字元到一個流中
用法: int fputs(char *string, FILE *stream);
程式例:

#include <stdio.h>

int main(void)
{
/* write a string to standard output */
fputs("Hello world\n", stdout);

return 0;
}

函式名: fread
功能: 從一個流中讀資料
用法: int fread(void *ptr, int size, int nitems, FILE *stream);
程式例:

#include <string.h>
#include <stdio.h>

int main(void)
{
FILE *stream;
char msg[] = "this is a test";
char buf[20];

if ((stream = fopen("DUMMY.FIL", "w+"))
== NULL)
{
fprintf(stderr,
"Cannot open output file.\n");
return 1;
}

/* write some data to the file */
fwrite(msg, strlen(msg)+1, 1, stream);

/* seek to the beginning of the file */
fseek(stream, SEEK_SET, 0);

/* read the data and display it */
fread(buf, strlen(msg)+1, 1, stream);
printf("%s\n", buf);

fclose(stream);
return 0;
}

函式名: free
功能: 釋放已分配的塊
用法: void free(void *ptr);
程式例:

#include <string.h>
#include <stdio.h>
#include <alloc.h>

int main(void)
{
char *str;

/* allocate memory for string */
str = malloc(10);

/* copy "Hello" to string */
strcpy(str, "Hello");

/* display string */
printf("String is %s\n", str);

/* free memory */
free(str);

return 0;
}

函式名: freemem
功能: 釋放先前分配的DOS記憶體塊
用法: int freemem(unsigned seg);
程式例:

#include <dos.h>
#include <alloc.h>
#include <stdio.h>

int main(void)
{
unsigned int size, segp;
int stat;

size = 64; /* (64 x 16) = 1024 bytes */
stat = allocmem(size, &segp);
if (stat < 0)
printf("Allocated memory at segment:\
%x\n", segp);
else
printf("Failed: maximum number of\
paragraphs available is %u\n",
stat);
freemem(segp);

return 0;
}

函式名: freopen
功能: 替換一個流
用法: FILE *freopen(char *filename, char *type, FILE *stream);
程式例:

#include <stdio.h>

int main(void)
{
/* redirect standard output to a file */
if (freopen("OUTPUT.FIL", "w", stdout)
== NULL)
fprintf(stderr, "error redirecting\
stdout\n");

/* this output will go to a file */
printf("This will go into a file.");

/* close the standard output stream */
fclose(stdout);

return 0;
}

函式名: frexp
功能: 把一個雙精度數分解為尾數的指數
用法: double frexp(double value, int *eptr);
程式例:

#include <math.h>
#include <stdio.h>

int main(void)
{
double mantissa, number;
int exponent;

number = 8.0;
mantissa = frexp(number, &exponent);

printf("The number %lf is ", number);
printf("%lf times two to the ", mantissa);
printf("power of %d\n", exponent);

return 0;
}

函式名: fscanf
功能: 從一個流中執行格式化輸入
用法: int fscanf(FILE *stream, char *format[,argument...]);
程式例:

#include <stdlib.h>
#include <stdio.h>

int main(void)
{
int i;

printf("Input an integer: ");

/* read an integer from the
standard input stream */
if (fscanf(stdin, "%d", &i))
printf("The integer read was: %i\n",
i);
else
{
fprintf(stderr, "Error reading an \
integer from stdin.\n");
exit(1);
}
return 0;
}

函式名: fseek
功能: 重定位流上的檔案指標
用法: int fseek(FILE *stream, long offset, int fromwhere);
程式例:

#include <stdio.h>

long filesize(FILE *stream);

int main(void)
{
FILE *stream;

stream = fopen("MYFILE.TXT", "w+");
fprintf(stream, "This is a test");
printf("Filesize of MYFILE.TXT is %ld bytes\n", filesize(stream));
fclose(stream);
return 0;
}

long filesize(FILE *stream)
{
long curpos, length;

curpos = ftell(stream);
fseek(stream, 0L, SEEK_END);
length = ftell(stream);
fseek(stream, curpos, SEEK_SET);
return length;
}

函式名: fsetpos
功能: 定位流上的檔案指標
用法: int fsetpos(FILE *stream, const fpos_t *pos);
程式例:

#include <stdlib.h>
#include <stdio.h>

void showpos(FILE *stream);

int main(void)
{
FILE *stream;
fpos_t filepos;

/* open a file for update */
stream = fopen("DUMMY.FIL", "w+");

/* save the file pointer position */
fgetpos(stream, &filepos);

/* write some data to the file */
fprintf(stream, "This is a test");

/* show the current file position */
showpos(stream);

/* set a new file position, display it */
if (fsetpos(stream, &filepos) == 0)
showpos(stream);
else
{
fprintf(stderr, "Error setting file \
pointer.\n");
exit(1);
}

/* close the file */
fclose(stream);
return 0;
}

void showpos(FILE *stream)
{
fpos_t pos;

/* display the current file pointer
position of a stream */
fgetpos(stream, &pos);
printf("File position: %ld\n", pos);
}

函式名: fstat
功能: 獲取開啟檔案資訊
用法: int fstat(char *handle, struct stat *buff);
程式例:

#include <sys\stat.h>
#include <stdio.h>
#include <time.h>

int main(void)
{
struct stat statbuf;
FILE *stream;

/* open a file for update */
if ((stream = fopen("DUMMY.FIL", "w+"))
== NULL)
{
fprintf(stderr, "Cannot open output \
file.\n");
return(1);
}
fprintf(stream, "This is a test");
fflush(stream);

/* get information about the file */
fstat(fileno(stream), &statbuf);
fclose(stream);

/* display the information returned */
if (statbuf.st_mode & S_IFCHR)
printf("Handle refers to a device.\n");
if (statbuf.st_mode & S_IFREG)
printf("Handle refers to an ordinary \
file.\n");
if (statbuf.st_mode & S_IREAD)
printf("User has read permission on \
file.\n");
if (statbuf.st_mode & S_IWRITE)
printf("User has write permission on \
file.\n");

printf("Drive letter of file: %c\n",
'A'+statbuf.st_dev);
printf("Size of file in bytes: %ld\n",
statbuf.st_size);
printf("Time file last opened: %s\n",
ctime(&statbuf.st_ctime));
return 0;
}

函式名: ftell
功能: 返回當前檔案指標
用法: long ftell(FILE *stream);
程式例:

#include <stdio.h>

int main(void)
{
FILE *stream;

stream = fopen("MYFILE.TXT", "w+");
fprintf(stream, "This is a test");
printf("The file pointer is at byte \
%ld\n", ftell(stream));
fclose(stream);
return 0;
}

函式名: fwrite
功能: 寫內容到流中
用法: int fwrite(void *ptr, int size, int nitems, FILE *stream);
程式例:

#include <stdio.h>

struct mystruct
{
int i;
char ch;
};

int main(void)
{
FILE *stream;
struct mystruct s;

if ((stream = fopen("TEST.$$$", "wb")) == NULL) /* open file TEST.$$$ */
{
fprintf(stderr, "Cannot open output file.\n");
return 1;
}
s.i = 0;
s.ch = 'A';
fwrite(&s, sizeof(s), 1, stream); /* write struct s to file */
fclose(stream); /* close file */
return 0;
}函式名: gcvt
功能: 把浮點數轉換成字串
用法: char *gcvt(double value, int ndigit, char *buf);
程式例:
#include <stdlib.h>
#include <stdio.h>

int main(void)
{
char str[25];
double num;
int sig = 5; /* significant digits */

/* a regular number */
num = 9.876;
gcvt(num, sig, str);
printf("string = %s\n", str);

/* a negative number */
num = -123.4567;
gcvt(num, sig, str);
printf("string = %s\n", str);

/* scientific notation */
num = 0.678e5;
gcvt(num, sig, str);
printf("string = %s\n", str);

return(0);
}

函式名: geninterrupt
功能: 產生一個軟中斷
用法: void geninterrupt(int intr_num);
程式例:

#include <conio.h>
#include <dos.h>

/* function prototype */
void writechar(char ch);

int main(void)
{
clrscr();
gotoxy(80,25);
writechar('*');
getch();
return 0;
}

/*
outputs a character at the current cursor
position using the video BIOS to avoid the
scrolling of the screen when writing to
location (80,25).
*/

void writechar(char ch)
{
struct text_info ti;
/* grab current text settings */
gettextinfo(&ti);
/* interrupt 0x10 sub-function 9 */
_AH = 9;
/* character to be output */
_AL = ch;
_BH = 0; /* video page */
_BL = ti.attribute; /* video attribute */
_CX = 1; /* repetition factor */
geninterrupt(0x10); /* output the char */
}

函式名: getarccoords
功能: 取得最後一次呼叫arc的座標
用法: void far getarccoords(struct arccoordstype far *arccoords);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
struct arccoordstype arcinfo;
int midx, midy;
int stangle = 45, endangle = 270;
char sstr[80], estr[80];

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
/* an error occurred */
if (errorcode != grOk)
{
printf("Graphics error: %s\n",
grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
/* terminate with an error code */
exit(1);
}

midx = getmaxx() / 2;
midy = getmaxy() / 2;

/* draw arc and get coordinates */
setcolor(getmaxcolor());
arc(midx, midy, stangle, endangle, 100);
getarccoords(&arcinfo);

/* convert arc information into strings */
sprintf(sstr, "*- (%d, %d)",
arcinfo.xstart, arcinfo.ystart);
sprintf(estr, "*- (%d, %d)",
arcinfo.xend, arcinfo.yend);

/* output the arc information */
outtextxy(arcinfo.xstart,
arcinfo.ystart, sstr);
outtextxy(arcinfo.xend,
arcinfo.yend, estr);

/* clean up */
getch();
closegraph();
return 0;
}

函式名: getaspectratio
功能: 返回當前圖形模式的縱橫比
用法: void far getaspectratio(int far *xasp, int far *yasp);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int xasp, yasp, midx, midy;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
/* an error occurred */
if (errorcode != grOk)
{
printf("Graphics error: %s\n",
grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
/* terminate with an error code */
exit(1);
}

midx = getmaxx() / 2;
midy = getmaxy() / 2;
setcolor(getmaxcolor());

/* get current aspect ratio settings */
getaspectratio(&xasp, &yasp);

/* draw normal circle */
circle(midx, midy, 100);
getch();

/* draw wide circle */
cleardevice();
setaspectratio(xasp/2, yasp);
circle(midx, midy, 100);
getch();

/* draw narrow circle */
cleardevice();
setaspectratio(xasp, yasp/2);
circle(midx, midy, 100);

/* clean up */
getch();
closegraph();
return 0;
}

函式名: getbkcolor
功能: 返回當前背景顏色
用法: int far getbkcolor(void);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int bkcolor, midx, midy;
char bkname[35];

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
/* an error occurred */
if (errorcode != grOk)
{
printf("Graphics error: %s\n",
grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
/* terminate with an error code */
exit(1);
}

midx = getmaxx() / 2;
midy = getmaxy() / 2;
setcolor(getmaxcolor());

/* for centering text on the display */
settextjustify(CENTER_TEXT, CENTER_TEXT);

/* get the current background color */
bkcolor = getbkcolor();

/* convert color value into a string */
itoa(bkcolor, bkname, 10);
strcat(bkname,
" is the current background color.");

/* display a message */
outtextxy(midx, midy, bkname);

/* clean up */
getch();
closegraph();
return 0;
}

函式名: getc
功能: 從流中取字元
用法: int getc(FILE *stream);
程式例:

#include <stdio.h>

int main(void)
{
char ch;

printf("Input a character:");
/* read a character from the
standard input stream */
ch = getc(stdin);
printf("The character input was: '%c'\n",
ch);
return 0;
}

函式名: getcbrk
功能: 獲取Control_break設定
用法: int getcbrk(void);
程式例: #include <stdio.h>
#include <dos.h>

int main(void)
{
if (getcbrk())
printf("Cntrl-brk flag is on\n");
else
printf("Cntrl-brk flag is off\n");

return 0;
}

函式名: getch
功能: 從控制檯無回顯地取一個字元
用法: int getch(void);
程式例:

#include <stdio.h>
#include <conio.h>

int main(void)
{
char ch;

printf("Input a character:");
ch = getche();
printf("\nYou input a '%c'\n", ch);
return 0;
}

函式名: getchar
功能: 從stdin流中讀字元
用法: int getchar(void);
程式例:

#include <stdio.h>

int main(void)
{
int c;

/* Note that getchar reads from stdin and
is line buffered; this means it will
not return until you press ENTER. */

while ((c = getchar()) != '\n')
printf("%c", c);

return 0;
}

函式名: getche
功能: 從控制檯取字元(帶回顯)
用法: int getche(void);
程式例:

#include <stdio.h>
#include <conio.h>

int main(void)
{
char ch;

printf("Input a character:");
ch = getche();
printf("\nYou input a '%c'\n", ch);
return 0;
}

函式名: getcolor
功能: 返回當前畫線顏色
用法: int far getcolor(void);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int color, midx, midy;
char colname[35];

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
/* an error occurred */
if (errorcode != grOk)
{
printf("Graphics error: %s\n",
grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
/* terminate with an error code */
exit(1);
}

midx = getmaxx() / 2;
midy = getmaxy() / 2;
setcolor(getmaxcolor());

/* for centering text on the display */
settextjustify(CENTER_TEXT, CENTER_TEXT);

/* get the current drawing color */
color = getcolor();

/* convert color value into a string */
itoa(color, colname, 10);
strcat(colname,
" is the current drawing color.");

/* display a message */
outtextxy(midx, midy, colname);

/* clean up */
getch();
closegraph();
return 0;
}

函式名: getcurdir
功能: 取指定驅動器的當前目錄
用法: int getcurdir(int drive, char *direc);
程式例:

#include <dir.h>
#include <stdio.h>
#include <string.h>

char *current_directory(char *path)
{
strcpy(path, "X:\\"); /* fill string with form of response: X:\ */
path[0] = 'A' + getdisk(); /* replace X with current drive letter */
getcurdir(0, path+3); /* fill rest of string with current directory */
return(path);
}

int main(void)
{
char curdir[MAXPATH];

current_directory(curdir);
printf("The current directory is %s\n", curdir);

return 0;
}

函式名: getcwd
功能: 取當前工作目錄
用法: char *getcwd(char *buf, int n);
程式例:

#include <stdio.h>
#include <dir.h>

int main(void)
{
char buffer[MAXPATH];

getcwd(buffer, MAXPATH);
printf("The current directory is: %s\n", buffer);
return 0;
}
函式名: getdate
功能: 取DOS日期
用法: void getdate(struct *dateblk);
程式例:

#include <dos.h>
#include <stdio.h>

int main(void)
{
struct date d;

getdate(&d);
printf("The current year is: %d\n",
d.da_year);
printf("The current day is: %d\n",
d.da_day);
printf("The current month is: %d\n",
d.da_mon);
return 0;
}

函式名: getdefaultpalette
功能: 返回撥色板定義結構
用法: struct palettetype *far getdefaultpalette(void);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int i;

/* structure for returning palette copy */
struct palettetype far *pal=(void *) 0;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
/* an error occurred */
if (errorcode != grOk)
{
printf("Graphics error: %s\n",
grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
/* terminate with an error code */
exit(1);
}

setcolor(getmaxcolor());

/* return a pointer to the default palette */
pal = getdefaultpalette();

for (i=0; i<16; i++)
{
printf("colors[%d] = %d\n", i,
pal->colors[i]);
getch();
}

/* clean up */
getch();
closegraph();
return 0;
}

函式名: getdisk
功能: 取當前磁碟驅動器號
用法: int getdisk(void);
程式例:

#include <stdio.h>
#include <dir.h>

int main(void)
{
int disk;

disk = getdisk() + 'A';
printf("The current drive is: %c\n",
disk);
return 0;
}

函式名: getdrivername
功能: 返回指向包含當前圖形驅動程式名字的字串指標
用法: char *getdrivename(void);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;

/* stores the device driver name */
char *drivername;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
/* an error occurred */
if (errorcode != grOk)
{
printf("Graphics error: %s\n",
grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
/* terminate with an error code */
exit(1);
}

setcolor(getmaxcolor());

/* get name of the device driver in use */
drivername = getdrivername();

/* for centering text on the screen */
settextjustify(CENTER_TEXT, CENTER_TEXT);

/* output the name of the driver */
outtextxy(getmaxx() / 2, getmaxy() / 2,
drivername);

/* clean up */
getch();
closegraph();
return 0;
}

函式名: getdta
功能: 取磁碟傳輸地址
用法: char far *getdta(void);
程式例:

#include <dos.h>
#include <stdio.h>

int main(void)
{
char far *dta;

dta = getdta();
printf("The current disk transfer \
address is: %Fp\n", dta);
return 0;
}

函式名: getenv
功能: 從環境中取字串
用法: char *getenv(char *envvar);
程式例:

#include <stdlib.h>
#include <stdio.h>

int main(void)
{
char *s;

s=getenv("COMSPEC"); /* get the comspec environment parameter */
printf("Command processor: %s\n",s); /* display comspec parameter */

return 0;
}

函式名: getfat, getfatd
功能: 取檔案分配表資訊
用法: void getfat(int drive, struct fatinfo *fatblkp);
程式例:

#include <stdio.h>
#include <dos.h>

int main(void)
{
struct fatinfo diskinfo;
int flag = 0;

printf("Please insert disk in drive A\n");
getchar();

getfat(1, &diskinfo);
/* get drive information */

printf("\nDrive A: is ");
switch((unsigned char) diskinfo.fi_fatid)
{
case 0xFD:
printf("360K low density\n");
break;

case 0xF9:
printf("1.2 Meg high density\n");
break;

default:
printf("unformatted\n");
flag = 1;
}

if (!flag)
{
printf(" sectors per cluster %5d\n",
diskinfo.fi_sclus);
printf(" number of clusters %5d\n",
diskinfo.fi_nclus);
printf(" bytes per sector %5d\n",
diskinfo.fi_bysec);
}

return 0;
}

函式名: getfillpattern
功能: 將使用者定義的填充模式拷貝到記憶體中
用法: void far getfillpattern(char far *upattern);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int maxx, maxy;
char pattern[8] = {0x00, 0x70, 0x20, 0x27, 0x25, 0x27, 0x04, 0x04};

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

maxx = getmaxx();
maxy = getmaxy();
setcolor(getmaxcolor());

/* select a user defined fill pattern */
setfillpattern(pattern, getmaxcolor());

/* fill the screen with the pattern */
bar(0, 0, maxx, maxy);

getch();

/* get the current user defined fill pattern */
getfillpattern(pattern);

/* alter the pattern we grabbed */
pattern[4] -= 1;
pattern[5] -= 3;
pattern[6] += 3;
pattern[7] -= 4;

/* select our new pattern */
setfillpattern(pattern, getmaxcolor());

/* fill the screen with the new pattern */
bar(0, 0, maxx, maxy);

/* clean up */
getch();
closegraph();
return 0;
}

函式名: getfillsettings
功能: 取得有關當前填充模式和填充顏色的資訊
用法: void far getfillsettings(struct fillsettingstype far *fillinfo);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

/ the names of the fill styles supported */
char *fname[] = { "EMPTY_FILL",
"SOLID_FILL",
"LINE_FILL",
"LTSLASH_FILL",
"SLASH_FILL",
"BKSLASH_FILL",
"LTBKSLASH_FILL",
"HATCH_FILL",
"XHATCH_FILL",
"INTERLEAVE_FILL",
"WIDE_DOT_FILL",
"CLOSE_DOT_FILL",
"USER_FILL"
};

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
struct fillsettingstype fillinfo;
int midx, midy;
char patstr[40], colstr[40];

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

midx = getmaxx() / 2;
midy = getmaxy() / 2;

/* get information about current fill pattern and color */
getfillsettings(&fillinfo);

/* convert fill information into strings */
sprintf(patstr, "%s is the fill style.", fname[fillinfo.pattern]);
sprintf(colstr, "%d is the fill color.", fillinfo.color);

/* display the information */
settextjustify(CENTER_TEXT, CENTER_TEXT);
outtextxy(midx, midy, patstr);
outtextxy(midx, midy+2*textheight("W"), colstr);

/* clean up */
getch();
closegraph();
return 0;
}

函式名: getftime
功能: 取檔案日期和時間
用法: int getftime(int handle, struct ftime *ftimep);
程式例:

#include <stdio.h>
#include <io.h>

int main(void)
{
FILE *stream;
struct ftime ft;

if ((stream = fopen("TEST.$$$",
"wt")) == NULL)
{
fprintf(stderr,
"Cannot open output file.\n");
return 1;
}
getftime(fileno(stream), &ft);
printf("File time: %u:%u:%u\n",
ft.ft_hour, ft.ft_min,
ft.ft_tsec * 2);
printf("File date: %u/%u/%u\n",
ft.ft_month, ft.ft_day,
ft.ft_year+1980);
fclose(stream);
return 0;
}

函式名: getgraphmode
功能: 返回當前圖形模式
用法: int far getgraphmode(void);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int midx, midy, mode;
char numname[80], modename[80];

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
/* an error occurred */
if (errorcode != grOk)
{
printf("Graphics error: %s\n",
grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
/* terminate with an error code */
exit(1);
}

midx = getmaxx() / 2;
midy = getmaxy() / 2;

/* get mode number and name strings */
mode = getgraphmode();
sprintf(numname,
"%d is the current mode number.",
mode);
sprintf(modename,
"%s is the current graphics mode",
getmodename(mode));

/* display the information */
settextjustify(CENTER_TEXT, CENTER_TEXT);
outtextxy(midx, midy, numname);
outtextxy(midx, midy+2*textheight("W"),
modename);

/* clean up */
getch();
closegraph();
return 0;
}

函式名: getftime
功能: 取檔案日期和時間
用法: int getftime(int handle, struct ftime *ftimep);
程式例:

#include <stdio.h>
#include <io.h>

int main(void)
{
FILE *stream;
struct ftime ft;

if ((stream = fopen("TEST.$$$",
"wt")) == NULL)
{
fprintf(stderr,
"Cannot open output file.\n");
return 1;
}
getftime(fileno(stream), &ft);
printf("File time: %u:%u:%u\n",
ft.ft_hour, ft.ft_min,
ft.ft_tsec * 2);
printf("File date: %u/%u/%u\n",
ft.ft_month, ft.ft_day,
ft.ft_year+1980);
fclose(stream);
return 0;
}
函式名: harderr
功能: 建立一個硬體錯誤處理程式
用法: void harderr(int (*fptr)());
程式例:
/*This program will trap disk errors and prompt
the user for action. Try running it with no
disk in drive A: to invoke its functions.*/

#include <stdio.h>
#include <conio.h>
#include <dos.h>
#define IGNORE 0
#define RETRY 1
#define ABORT 2
int buf[500];
/*define the error messages for trapping disk problems*/
static char *err_msg[] = {
"write protect",
"unknown unit",
"drive not ready",
"unknown command",
"data error (CRC)",
"bad request",
"seek error",
"unknown media type",
"sector not found",
"printer out of paper",
"write fault",
"read fault",
"general failure",
"reserved",
"reserved",
"invalid disk change"
};

error_win(char *msg)
{
int retval;

cputs(msg);

/*prompt for user to press a key to abort, retry, ignore*/
while(1)
{
retval= getch();
if (retval == 'a' || retval == 'A')
{
retval = ABORT;
break;
}
if (retval == 'r' || retval == 'R')
{
retval = RETRY;
break;
}
if (retval == 'i' || retval == 'I')
{
retval = IGNORE;
break;
}
}

return(retval);
}

/*pragma warn -par reduces warnings which occur
due to the non use of the parameters errval,
bp and si to the handler.*/
#pragma warn -par

int handler(int errval,int ax,int bp,int si)
{
static char msg[80];
unsigned di;
int drive;
int errorno;
di= _DI;
/*if this is not a disk error then it was
another device having trouble*/

if (ax < 0)
{
/* report the error */
error_win("Device error");
/* and return to the program directly requesting abort */
hardretn(ABORT);
}
/* otherwise it was a disk error */
drive = ax & 0x00FF;
errorno = di & 0x00FF;
/* report which error it was */
sprintf(msg, "Error: %s on drive %c\r\nA)bort, R)etry, I)gnore: ",
err_msg[errorno], 'A' + drive);
/*
return to the program via dos interrupt 0x23 with abort, retry,
or ignore as input by the user.
*/
hardresume(error_win(msg));
return ABORT;
}
#pragma warn +par

int main(void)
{
/*
install our handler on the hardware problem interrupt
*/
harderr(handler);
clrscr();
printf("Make sure there is no disk in drive A:\n");
printf("Press any key ....\n");
getch();
printf("Trying to access drive A:\n");
printf("fopen returned %p\n",fopen("A:temp.dat", "w"));
return 0;
}

函式名: hardresume
功能: 硬體錯誤處理函式
用法: void hardresume(int rescode);
程式例:

/* This program will trap disk errors and prompt the user for action. */
/* Try running it with no disk in drive A: to invoke its functions */

#include <stdio.h>
#include <conio.h>
#include <dos.h>

#define IGNORE 0
#define RETRY 1
#define ABORT 2

int buf[500];

/* define the error messages for trapping disk problems */
static char *err_msg[] = {
"write protect",
"unknown unit",
"drive not ready",
"unknown command",
"data error (CRC)",
"bad request",
"seek error",
"unknown media type",
"sector not found",
"printer out of paper",
"write fault",
"read fault",
"general failure",
"reserved",
"reserved",
"invalid disk change"
};

error_win(char *msg)
{
int retval;

cputs(msg);

/* prompt for user to press a key to abort, retry, ignore */
while(1)
{
retval= getch();
if (retval == 'a' || retval == 'A')
{
retval = ABORT;
break;
}
if (retval == 'r' || retval == 'R')
{
retval = RETRY;
break;
}
if (retval == 'i' || retval == 'I')
{
retval = IGNORE;
break;
}
}

return(retval);
}

/* pragma warn -par reduces warnings which occur due to the non use */
/* of the parameters errval, bp and si to the handler. */
#pragma warn -par

int handler(int errval,int ax,int bp,int si)
{
static char msg[80];
unsigned di;
int drive;
int errorno;

di= _DI;
/* if this is not a disk error then it was another device having trouble */

if (ax < 0)
{
/* report the error */
error_win("Device error");
/* and return to the program directly
requesting abort */
hardretn(ABORT);
}
/* otherwise it was a disk error */
drive = ax & 0x00FF;
errorno = di & 0x00FF;
/* report which error it was */
sprintf(msg, "Error: %s on drive %c\r\nA)bort, R)etry, I)gnore: ",
err_msg[errorno], 'A' + drive);
/* return to the program via dos interrupt 0x23 with abort, retry */
/* or ignore as input by the user. */
hardresume(error_win(msg));
return ABORT;
}
#pragma warn +par

int main(void)
{
/* install our handler on the hardware problem interrupt */
harderr(handler);
clrscr();
printf("Make sure there is no disk in drive A:\n");
printf("Press any key ....\n");
getch();
printf("Trying to access drive A:\n");
printf("fopen returned %p\n",fopen("A:temp.dat", "w"));
return 0;
}

函式名: highvideo
功能: 選擇高亮度文字字元
用法: void highvideo(void);
程式例:

#include <conio.h>

int main(void)
{
clrscr();

lowvideo();
cprintf("Low Intensity text\r\n");
highvideo();
gotoxy(1,2);
cprintf("High Intensity Text\r\n");

return 0;
}

函式名: hypot
功能: 計算直角三角形的斜邊長
用法: double hypot(double x, double y);
程式例:

#include <stdio.h>
#include <math.h>

int main(void)
{
double result;
double x = 3.0;
double y = 4.0;

result = hypot(x, y);
printf("The hypotenuse is: %lf\n", result);

return 0;
}
函式名: kbhit
功能: 檢查當前按下的鍵
用法: int kbhit(void);
程式例:
#include <conio.h>

int main(void)
{
cprintf("Press any key to continue:");
while (!kbhit()) /* do nothing */ ;
cprintf("\r\nA key was pressed...\r\n");
return 0;
}

函式名: keep
功能: 退出並繼續駐留
用法: void keep(int status, int size);
程式例:

/***NOTE:
This is an interrupt service routine. You
can NOT compile this program with Test
Stack Overflow turned on and get an
executable file which will operate
correctly. Due to the nature of this
function the formula used to compute
the number of paragraphs may not
necessarily work in all cases. Use with
care! Terminate Stay Resident (TSR)
programs are complex and no other support
for them is provided. Refer to the
MS-DOS technical documentation
for more information. */
#include <dos.h>
/* The clock tick interrupt */
#define INTR 0x1C
/* Screen attribute (blue on grey) */
#define ATTR 0x7900

/* reduce heaplength and stacklength
to make a smaller program in memory */
extern unsigned _heaplen = 1024;
extern unsigned _stklen = 512;

void interrupt ( *oldhandler)(void);

void interrupt handler(void)
{
unsigned int (far *screen)[80];
static int count;

/* For a color screen the video memory
is at B800:0000. For a monochrome
system use B000:000 */
screen = MK_FP(0xB800,0);

/* increase the counter and keep it
within 0 to 9 */
count++;
count %= 10;

/* put the number on the screen */
screen[0][79] = count + '0' + ATTR;

/* call the old interrupt handler */
oldhandler();
}

int main(void)
{

/* get the address of the current clock
tick interrupt */
oldhandler = getvect(INTR);

/* install the new interrupt handler */
setvect(INTR, handler);

/* _psp is the starting address of the
program in memory. The top of the stack
is the end of the program. Using _SS and
_SP together we can get the end of the
stack. You may want to allow a bit of
saftey space to insure that enough room
is being allocated ie:
(_SS + ((_SP + safety space)/16) - _psp)
*/
keep(0, (_SS + (_SP/16) - _psp));
return 0;
} main()主函式
每一C 程式都必須有一main()函式, 可以根據自己的愛好把它放在程式的某
個地方。有些程式設計師把它放在最前面, 而另一些程式設計師把它放在最後面, 無論放
在哪個地方, 以下幾點說明都是適合的。
1. main() 引數
在Turbo C2.0啟動過程中, 傳遞main()函式三個引數: argc, argv和env。
* argc: 整數, 為傳給main()的命令列引數個數。
* argv: 字串陣列。
在DOS 3.X 版本中, argv[0] 為程式執行的全路徑名; 對DOS 3.0
以下的版本, argv[0]為空串("") 。
argv[1] 為在DOS命令列中執行程式名後的第一個字串;
argv[2] 為執行程式名後的第二個字串;
...
argv[argc]為NULL。
*env: 安符串陣列。env[] 的每一個元素都包含ENVVAR=value形式的字元
串。其中ENVVAR為環境變數如PATH或87。value 為ENVVAR的對應值如C:\DOS, C:
\TURBOC(對於PATH) 或YES(對於87)。
Turbo C2.0啟動時總是把這三個引數傳遞給main()函式, 可以在使用者程式中
說明(或不說明)它們, 如果說明了部分(或全部)引數, 它們就成為main()子程式
的區域性變數。
請注意: 一旦想說明這些引數, 則必須按argc, argv, env 的順序, 如以下
的例子:
main()
main(int argc)
main(int argc, char *argv[])
main(int argc, char *argv[], char *env[])
其中第二種情況是合法的, 但不常見, 因為在程式中很少有隻用argc, 而不
用argv[]的情況。
以下提供一樣例程式EXAMPLE.EXE, 演示如何在main()函式中使用三個引數:
/*program name EXAMPLE.EXE*/
#include <stdio.h>
#include <stdlib.h>
main(int argc, char *argv[], char *env[])
{
int i;
printf("These are the %d command- line arguments passed to
main:\n\n", argc);
for(i=0; i<=argc; i++)
printf("argv[%d]:%s\n", i, argv[i]);
printf("\nThe environment string(s)on this system are:\n\n");
for(i=0; env[i]!=NULL; i++)
printf(" env[%d]:%s\n", i, env[i]);
}
如果在DOS 提示符下, 按以下方式執行EXAMPLE.EXE:
C:\example first_argument "argument with blanks" 3 4 "last but
one" stop!
注意: 可以用雙引號括起內含空格的引數, 如本例中的: " argument
with blanks"和"Last but one")。
結果是這樣的:
The value of argc is 7
These are the 7 command-linearguments passed to main:
argv[0]:C:\TURBO\EXAMPLE.EXE
argv[1]:first_argument
argv[2]:argument with blanks
argv[3]:3
argv[4]:4
argv[5]:last but one
argv[6]:stop!
argv[7]:(NULL)
The environment string(s) on this system are:
env[0]: COMSPEC=C:\COMMAND.COM
env[1]: PROMPT=$P$G /*視具體設定而定*/
env[2]: PATH=C:\DOS;C:\TC /*視具體設定而定*/

應該提醒的是: 傳送main() 函式的命令列引數的最大長度為128 個字元 (包
括引數間的空格), 這是由DOS 限制的。

函式名: matherr
功能: 使用者可修改的數學錯誤處理程式
用法: int matherr(struct exception *e);
程式例:

/* This is a user-defined matherr function that prevents
any error messages from being printed. */

#include<math.h>

int matherr(struct exception *a)
{
return 1;
}

函式名: memccpy
功能: 從源source中拷貝n個位元組到目標destin中
用法: void *memccpy(void *destin, void *source, unsigned char ch,
unsigned n);
程式例:

#include <string.h>
#include <stdio.h>

int main(void)
{
char *src = "This is the source string";
char dest[50];
char *ptr;

ptr = memccpy(dest, src, 'c', strlen(src));

if (ptr)
{
*ptr = '\0';
printf("The character was found: %s\n", dest);
}
else
printf("The character wasn't found\n");
return 0;
}

函式名: malloc
功能: 記憶體分配函式
用法: void *malloc(unsigned size);
程式例:

#include <stdio.h>
#include <string.h>
#include <alloc.h>
#include <process.h>

int main(void)
{
char *str;

/* allocate memory for string */
/* This will generate an error when compiling */
/* with C++, use the new operator instead. */
if ((str = malloc(10)) == NULL)
{
printf("Not enough memory to allocate buffer\n");
exit(1); /* terminate program if out of memory */
}

/* copy "Hello" into string */
strcpy(str, "Hello");

/* display string */
printf("String is %s\n", str);

/* free memory */
free(str);

return 0;
}

函式名: memchr
功能: 在陣列的前n個位元組中搜尋字元
用法: void *memchr(void *s, char ch, unsigned n);
程式例:

#include <string.h>
#include <stdio.h>

int main(void)
{
char str[17];
char *ptr;

strcpy(str, "This is a string");
ptr = memchr(str, 'r', strlen(str));
if (ptr)
printf("The character 'r' is at position: %d\n", ptr - str);
else
printf("The character was not found\n");
return 0;
}

函式名: memcpy
功能: 從源source中拷貝n個位元組到目標destin中
用法: void *memcpy(void *destin, void *source, unsigned n);
程式例:

#include <stdio.h>
#include <string.h>
int main(void)
{
char src[] = "******************************";
char dest[] = "abcdefghijlkmnopqrstuvwxyz0123456709";
char *ptr;
printf("destination before memcpy: %s\n", dest);
ptr = memcpy(dest, src, strlen(src));
if (ptr)
printf("destination after memcpy: %s\n", dest);
else
printf("memcpy failed\n");
return 0;
}

函式名: memicmp
功能: 比較兩個串s1和s2的前n個位元組, 忽略大小寫
用法: int memicmp(void *s1, void *s2, unsigned n);
程式例:

#include <stdio.h>
#include <string.h>

int main(void)
{
char *buf1 = "ABCDE123";
char *buf2 = "abcde456";
int stat;
stat = memicmp(buf1, buf2, 5);
printf("The strings to position 5 are ");
if (stat)
printf("not ");
printf("the same\n");
return 0;
}

函式名: memmove
功能: 移動一塊位元組
用法: void *memmove(void *destin, void *source, unsigned n);
程式例:

#include <string.h>
#include <stdio.h>

int main(void)
{
char *dest = "abcdefghijklmnopqrstuvwxyz0123456789";
char *src = "******************************";
printf("destination prior to memmove: %s\n", dest);
memmove(dest, src, 26);
printf("destination after memmove: %s\n", dest);
return 0;
}

函式名: memset
功能: 設定s中的所有位元組為ch, s陣列的大小由n給定
用法: void *memset(void *s, char ch, unsigned n);
程式例:

#include <string.h>
#include <stdio.h>
#include <mem.h>

int main(void)
{
char buffer[] = "Hello world\n";

printf("Buffer before memset: %s\n", buffer);
memset(buffer, '*', strlen(buffer) - 1);
printf("Buffer after memset: %s\n", buffer);
return 0;
}

函式名: mkdir
功能: 建立一個目錄
用法: int mkdir(char *pathname);
程式例:

#include <stdio.h>
#include <conio.h>
#include <process.h>
#include <dir.h>

int main(void)
{
int status;

clrscr();
status = mkdir("asdfjklm");
(!status) ? (printf("Directory created\n")) :
(printf("Unable to create directory\n"));

getch();
system("dir");
getch();

status = rmdir("asdfjklm");
(!status) ? (printf("Directory deleted\n")) :
(perror("Unable to delete directory"));

return 0;
}

函式名: mktemp
功能: 建立唯一的檔名
用法: char *mktemp(char *template);
程式例:

#include <dir.h>
#include <stdio.h>

int main(void)
{
/* fname defines the template for the
temporary file. */

char *fname = "TXXXXXX", *ptr;

ptr = mktemp(fname);
printf("%s\n",ptr);
return 0;
}

函式名: MK_FP
功能: 設定一個遠指標
用法: void far *MK_FP(unsigned seg, unsigned off);
程式例:

#include <dos.h>
#include <graphics.h>

int main(void)
{
int gd, gm, i;
unsigned int far *screen;

detectgraph(&gd, &gm);
if (gd == HERCMONO)
screen = MK_FP(0xB000, 0);
else
screen = MK_FP(0xB800, 0);
for (i=0; i<26; i++)
screen[i] = 0x0700 + ('a' + i);
return 0;
}

函式名: modf
功能: 把數分為指數和尾數
用法: double modf(double value, double *iptr);
程式例:

#include <math.h>
#include <stdio.h>

int main(void)
{
double fraction, integer;
double number = 100000.567;

fraction = modf(number, &integer);
printf("The whole and fractional parts of %lf are %lf and %lf\n",
number, integer, fraction);
return 0;
}

函式名: movedata
功能: 拷貝位元組
用法: void movedata(int segsrc, int offsrc, int segdest,
int offdest, unsigned numbytes);
程式例:

#include <mem.h>

#define MONO_BASE 0xB000

/* saves the contents of the monochrome screen in buffer */
void save_mono_screen(char near *buffer)
{
movedata(MONO_BASE, 0, _DS, (unsigned)buffer, 80*25*2);
}

int main(void)
{
char buf[80*25*2];
save_mono_screen(buf);
}

函式名: moverel
功能: 將當前位置(CP)移動一相對距離
用法: void far moverel(int dx, int dy);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
char msg[80];

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

/* move the C.P. to location (20, 30) */
moveto(20, 30);

/* plot a pixel at the C.P. */
putpixel(getx(), gety(), getmaxcolor());

/* create and output a message at (20, 30) */
sprintf(msg, " (%d, %d)", getx(), gety());
outtextxy(20, 30, msg);

/* move to a point a relative distance */
/* away from the current value of C.P. */
moverel(100, 100);

/* plot a pixel at the C.P. */
putpixel(getx(), gety(), getmaxcolor());

/* create and output a message at C.P. */
sprintf(msg, " (%d, %d)", getx(), gety());
outtext(msg);

/* clean up */
getch();
closegraph();
return 0;
}

函式名: movetext
功能: 將螢幕文字從一個矩形區域拷貝到另一個矩形區域
用法: int movetext(int left, int top, int right, int bottom,
int newleft, int newtop);
程式例:
#include <conio.h>
#include <string.h>

int main(void)
{
char *str = "This is a test string";

clrscr();
cputs(str);
getch();

movetext(1, 1, strlen(str), 2, 10, 10);
getch();

return 0;
}

函式名: moveto
功能: 將CP移到(x, y)
用法: void far moveto(int x, int y);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
char msg[80];

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

/* move the C.P. to location (20, 30) */
moveto(20, 30);

/* plot a pixel at the C.P. */
putpixel(getx(), gety(), getmaxcolor());

/* create and output a message at (20, 30) */
sprintf(msg, " (%d, %d)", getx(), gety());
outtextxy(20, 30, msg);

/* move to (100, 100) */
moveto(100, 100);

/* plot a pixel at the C.P. */
putpixel(getx(), gety(), getmaxcolor());

/* create and output a message at C.P. */
sprintf(msg, " (%d, %d)", getx(), gety());
outtext(msg);

/* clean up */
getch();
closegraph();
return 0;
}

函式名: movemem
功能: 移動一塊位元組
用法: void movemem(void *source, void *destin, unsigned len);
程式例:

#include <mem.h>
#include <alloc.h>
#include <stdio.h>
#include <string.h>

int main(void)
{
char *source = "Borland International";
char *destination;
int length;

length = strlen(source);
destination = malloc(length + 1);
movmem(source,destination,length);
printf("%s\n",destination);

return 0;
}

函式名: normvideo
功能: 選擇正常亮度字元
用法: void normvideo(void);
程式例:

#include <conio.h>

int main(void)
{
normvideo();
cprintf("NORMAL Intensity Text\r\n");
return 0;
}

函式名: nosound
功能: 關閉PC揚聲器
用法: void nosound(void);
程式例:

/* Emits a 7-Hz tone for 10 seconds.

True story: 7 Hz is the resonant frequency of a chicken's skull cavity.
This was determined empirically in Australia, where a new factory
generating 7-Hz tones was located too close to a chicken ranch:
When the factory started up, all the chickens died.

Your PC may not be able to emit a 7-Hz tone.
*/

int main(void)
{
sound(7);
delay(10000);
nosound();
}
函式名: open
功能: 開啟一個檔案用於讀或寫
用法: int open(char *pathname, int access[, int permiss]);
程式例:
#include <string.h>
#include <stdio.h>
#include <fcntl.h>
#include <io.h>

int main(void)
{
int handle;
char msg[] = "Hello world";

if ((handle = open("TEST.$$$", O_CREAT | O_TEXT)) == -1)
{
perror("Error:");
return 1;
}
write(handle, msg, strlen(msg));
close(handle);
return 0;
}

函式名: outport
功能: 輸出整數到硬體埠中
用法: void outport(int port, int value);
程式例:

#include <stdio.h>
#include <dos.h>

int main(void)
{
int value = 64;
int port = 0;

outportb(port, value);
printf("Value %d sent to port number %d\n", value, port);
return 0;
}

函式名: outportb
功能: 輸出位元組到硬體埠中
用法: void outportb(int port, char byte);
程式例:

#include <stdio.h>
#include <dos.h>

int main(void)
{
int value = 64;
int port = 0;

outportb(port, value);
printf("Value %d sent to port number %d\n", value, port);
return 0;
}

函式名: outtext
功能: 在視區顯示一個字串
用法: void far outtext(char far *textstring);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int midx, midy;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

midx = getmaxx() / 2;
midy = getmaxy() / 2;

/* move the C.P. to the center of the screen */
moveto(midx, midy);

/* output text starting at the C.P. */
outtext("This ");
outtext("is ");
outtext("a ");
outtext("test.");

/* clean up */
getch();
closegraph();
return 0;
}

函式名: outtextxy
功能: 在指定位置顯示一字串
用法: void far outtextxy(int x, int y, char *textstring);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int midx, midy;

/* initialize graphics and local variables */
initgraph( &gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

midx = getmaxx() / 2;
midy = getmaxy() / 2;

/* output text at the center of the screen*/
/* Note: the C.P. doesn't get changed.*/
outtextxy(midx, midy, "This is a test.");

/* clean up */
getch();
closegraph();
return 0;
}
函式名: parsfnm
功能: 分析檔名
用法: char *parsfnm (char *cmdline, struct fcb *fcbptr, int option);
程式例:

#include <process.h>
#include <string.h>
#include <stdio.h>
#include <dos.h>

int main(void)
{
char line[80];
struct fcb blk;

/* get file name */
printf("Enter drive and file name (no path - ie. a:file.dat)\n");
gets(line);

/* put file name in fcb */
if (parsfnm(line, &blk, 1) == NULL)
printf("Error in parsfm call\n");
else
printf("Drive #%d Name: %11s\n", blk.fcb_drive, blk.fcb_name);

return 0;
}

函式名: peek
功能: 檢查儲存單元
用法: int peek(int segment, unsigned offset);
程式例:

#include <stdio.h>
#include <conio.h>
#include <dos.h>

int main(void)
{
int value = 0;

printf("The current status of your keyboard is:\n");
value = peek(0x0040, 0x0017);
if (value & 1)
printf("Right shift on\n");
else
printf("Right shift off\n");

if (value & 2)
printf("Left shift on\n");
else
printf("Left shift off\n");

if (value & 4)
printf("Control key on\n");
else
printf("Control key off\n");

if (value & 8)
printf("Alt key on\n");
else
printf("Alt key off\n");

if (value & 16)
printf("Scroll lock on\n");
else
printf("Scroll lock off\n");

if (value & 32)
printf("Num lock on\n");
else
printf("Num lock off\n");

if (value & 64)
printf("Caps lock on\n");
else
printf("Caps lock off\n");

return 0;
}

函式名: peekb
功能: 檢查儲存單元
用法: char peekb (int segment, unsigned offset);
程式例:

#include <stdio.h>
#include <conio.h>
#include <dos.h>

int main(void)
{
int value = 0;

printf("The current status of your keyboard is:\n");
value = peekb(0x0040, 0x0017);
if (value & 1)
printf("Right shift on\n");
else
printf("Right shift off\n");

if (value & 2)
printf("Left shift on\n");
else
printf("Left shift off\n");

if (value & 4)
printf("Control key on\n");
else
printf("Control key off\n");

if (value & 8)
printf("Alt key on\n");
else
printf("Alt key off\n");

if (value & 16)
printf("Scroll lock on\n");
else
printf("Scroll lock off\n");

if (value & 32)
printf("Num lock on\n");
else
printf("Num lock off\n");

if (value & 64)
printf("Caps lock on\n");
else
printf("Caps lock off\n");

return 0;
}

函式名: perror
功能: 系統錯誤資訊
用法: void perror(char *string);
程式例:

#include <stdio.h>

int main(void)
{
FILE *fp;

fp = fopen("perror.dat", "r");
if (!fp)
perror("Unable to open file for reading");
return 0;
}

函式名: pieslice
功能: 繪製並填充一個扇形
用法: void far pieslice(int x, int stanle, int endangle, int radius);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int midx, midy;
int stangle = 45, endangle = 135, radius = 100;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

midx = getmaxx() / 2;
midy = getmaxy() / 2;

/* set fill style and draw a pie slice */
setfillstyle(EMPTY_FILL, getmaxcolor());
pieslice(midx, midy, stangle, endangle, radius);

/* clean up */
getch();
closegraph();
return 0;
}

函式名: poke
功能: 存值到一個給定儲存單元
用法: void poke(int segment, int offset, int value);
程式例:

#include <dos.h>
#include <conio.h>

int main(void)
{
clrscr();
cprintf("Make sure the scroll lock key is off and press any key\r\n");
getch();
poke(0x0000,0x0417,16);
cprintf("The scroll lock is now on\r\n");
return 0;
}

函式名: pokeb
功能: 存值到一個給定儲存單元
用法: void pokeb(int segment, int offset, char value);
程式例:

#include <dos.h>
#include <conio.h>

int main(void)
{
clrscr();
cprintf("Make sure the scroll lock key is off and press any key\r\n");
getch();
pokeb(0x0000,0x0417,16);
cprintf("The scroll lock is now on\r\n");
return 0;
}

函式名: poly
功能: 根據引數產生一個多項式
用法: double poly(double x, int n, double c[]);
程式例:

#include <stdio.h>
#include <math.h>

/* polynomial: x**3 - 2x**2 + 5x - 1 */

int main(void)
{
double array[] = { -1.0, 5.0, -2.0, 1.0 };
double result;

result = poly(2.0, 3, array);
printf("The polynomial: x**3 - 2.0x**2 + 5x - 1 at 2.0 is %lf\n",
result);
return 0;
}

函式名: pow
功能: 指數函式(x的y次方)
用法: double pow(double x, double y);
程式例:

#include <math.h>
#include <stdio.h>

int main(void)
{
double x = 2.0, y = 3.0;

printf("%lf raised to %lf is %lf\n", x, y, pow(x, y));
return 0;
}

函式名: pow10
功能: 指數函式(10的p次方)
用法: double pow10(int p);
程式例:

#include <math.h>
#include <stdio.h>

int main(void)
{
double p = 3.0;

printf("Ten raised to %lf is %lf\n", p, pow10(p));
return 0;
}

函式名: printf
功能: 產生格式化輸出的函式
用法: int printf(char *format...);
程式例:

#include <stdio.h>
#include <string.h>

#define I 555
#define R 5.5

int main(void)
{
int i,j,k,l;
char buf[7];
char *prefix = buf;
char tp[20];
printf("prefix 6d 6o 8x 10.2e "
"10.2f\n");
strcpy(prefix,"%");
for (i = 0; i < 2; i++)
{
for (j = 0; j < 2; j++)
for (k = 0; k < 2; k++)
for (l = 0; l < 2; l++)
{
if (i==0) strcat(prefix,"-");
if (j==0) strcat(prefix,"+");
if (k==0) strcat(prefix,"#");
if (l==0) strcat(prefix,"0");
printf("%5s |",prefix);
strcpy(tp,prefix);
strcat(tp,"6d |");
printf(tp,I);
strcpy(tp,"");
strcpy(tp,prefix);
strcat(tp,"6o |");
printf(tp,I);
strcpy(tp,"");
strcpy(tp,prefix);
strcat(tp,"8x |");
printf(tp,I);
strcpy(tp,"");
strcpy(tp,prefix);
strcat(tp,"10.2e |");
printf(tp,R);
strcpy(tp,prefix);
strcat(tp,"10.2f |");
printf(tp,R);
printf(" \n");
strcpy(prefix,"%");
}
}
return 0;
}

函式名: putc
功能: 輸出一字元到指定流中
用法: int putc(int ch, FILE *stream);
程式例:

#include <stdio.h>

int main(void)
{
char msg[] = "Hello world\n";
int i = 0;

while (msg[i])
putc(msg[i++], stdout);
return 0;
}

函式名: putch
功能: 輸出字元到控制檯
用法: int putch(int ch);
程式例:

#include <stdio.h>
#include <conio.h>

int main(void)
{
char ch = 0;

printf("Input a string:");
while ((ch != '\r'))
{
ch = getch();
putch(ch);
}
return 0;
}

函式名: putchar
功能: 在stdout上輸出字元
用法: int putchar(int ch);
程式例:

#include <stdio.h>

/* define some box-drawing characters */
#define LEFT_TOP 0xDA
#define RIGHT_TOP 0xBF
#define HORIZ 0xC4
#define VERT 0xB3
#define LEFT_BOT 0xC0
#define RIGHT_BOT 0xD9

int main(void)
{
char i, j;

/* draw the top of the box */
putchar(LEFT_TOP);
for (i=0; i<10; i++)
putchar(HORIZ);
putchar(RIGHT_TOP);
putchar('\n');

/* draw the middle */
for (i=0; i<4; i++)
{
putchar(VERT);
for (j=0; j<10; j++)
putchar(' ');
putchar(VERT);
putchar('\n');
}

/* draw the bottom */
putchar(LEFT_BOT);
for (i=0; i<10; i++)
putchar(HORIZ);
putchar(RIGHT_BOT);
putchar('\n');

return 0;
}

函式名: putenv
功能: 把字串加到當前環境中
用法: int putenv(char *envvar);
程式例:

#include <stdio.h>
#include <stdlib.h>
#include <alloc.h>
#include <string.h>
#include <dos.h>

int main(void)
{
char *path, *ptr;
int i = 0;

/* get the current path environment */
ptr = getenv("PATH");

/* set up new path */
path = malloc(strlen(ptr)+15);
strcpy(path,"PATH=");
strcat(path,ptr);
strcat(path,";c:\\temp");

/* replace the current path and display current environment */
putenv(path);
while (environ[i])
printf("%s\n",environ[i++]);

return 0;
}

函式名: putimage
功能: 在螢幕上輸出一個點陣圖
用法: void far putimage(int x, int y, void far *bitmap, int op);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

#define ARROW_SIZE 10

void draw_arrow(int x, int y);

int main(void)
{
/* request autodetection */
int gdriver = DETECT, gmode, errorcode;
void *arrow;
int x, y, maxx;
unsigned int size;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

maxx = getmaxx();
x = 0;
y = getmaxy() / 2;

/* draw the image to be grabbed */
draw_arrow(x, y);

/* calculate the size of the image */
size = imagesize(x, y-ARROW_SIZE, x+(4*ARROW_SIZE), y+ARROW_SIZE);

/* allocate memory to hold the image */
arrow = malloc(size);

/* grab the image */
getimage(x, y-ARROW_SIZE, x+(4*ARROW_SIZE), y+ARROW_SIZE, arrow);

/* repeat until a key is pressed */
while (!kbhit())
{
/* erase old image */
putimage(x, y-ARROW_SIZE, arrow, XOR_PUT);

x += ARROW_SIZE;
if (x >= maxx)
x = 0;

/* plot new image */
putimage(x, y-ARROW_SIZE, arrow, XOR_PUT);
}

/* clean up */
free(arrow);
closegraph();
return 0;
}

void draw_arrow(int x, int y)
{
/* draw an arrow on the screen */
moveto(x, y);
linerel(4*ARROW_SIZE, 0);
linerel(-2*ARROW_SIZE, -1*ARROW_SIZE);
linerel(0, 2*ARROW_SIZE);
linerel(2*ARROW_SIZE, -1*ARROW_SIZE);
}

函式名: putpixel
功能: 在指定位置畫一畫素
用法: void far putpixel (int x, int y, int pixelcolor);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>
#include <dos.h>

#define PIXEL_COUNT 1000
#define DELAY_TIME 100 /* in milliseconds */

int main(void)
{
/* request autodetection */
int gdriver = DETECT, gmode, errorcode;
int i, x, y, color, maxx, maxy, maxcolor, seed;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

maxx = getmaxx() + 1;
maxy = getmaxy() + 1;
maxcolor = getmaxcolor() + 1;

while (!kbhit())
{
/* seed the random number generator */
seed = random(32767);
srand(seed);
for (i=0; i<PIXEL_COUNT; i++)
{
x = random(maxx);
y = random(maxy);
color = random(maxcolor);
putpixel(x, y, color);
}

delay(DELAY_TIME);
srand(seed);
for (i=0; i<PIXEL_COUNT; i++)
{
x = random(maxx);
y = random(maxy);
color = random(maxcolor);
if (color == getpixel(x, y))
putpixel(x, y, 0);
}
}

/* clean up */
getch();
closegraph();
return 0;
}

函式名: puts
功能: 送一字串到流中
用法: int puts(char *string);
程式例:

#include <stdio.h>
int main(void)
{
char string[] = "This is an example output string\n";

puts(string);
return 0;
}

函式名: puttext
功能: 將文字從儲存區拷貝到螢幕
用法: int puttext(int left, int top, int right, int bottom, void *source);
程式例:

#include <conio.h>
int main(void)
{
char buffer[512];

/* put some text to the console */
clrscr();
gotoxy(20, 12);
cprintf("This is a test. Press any key to continue ...");
getch();

/* grab screen contents */
gettext(20, 12, 36, 21,buffer);
clrscr();

/* put selected characters back to the screen */
gotoxy(20, 12);
puttext(20, 12, 36, 21, buffer);
getch();

return 0;
}

函式名: putw
功能: 把一字元或字送到流中
用法: int putw(int w, FILE *stream);
程式例:

#include <stdio.h>
#include <stdlib.h>

#define FNAME "test.$$$"

int main(void)
{
FILE *fp;
int word;

/* place the word in a file */
fp = fopen(FNAME, "wb");
if (fp == NULL)
{
printf("Error opening file %s\n", FNAME);
exit(1);
}

word = 94;
putw(word,fp);
if (ferror(fp))
printf("Error writing to file\n");
else
printf("Successful write\n");
fclose(fp);

/* reopen the file */
fp = fopen(FNAME, "rb");
if (fp == NULL)
{
printf("Error opening file %s\n", FNAME);
exit(1);
}

/* extract the word */
word = getw(fp);
if (ferror(fp))
printf("Error reading file\n");
else
printf("Successful read: word = %d\n", word);

/* clean up */
fclose(fp);
unlink(FNAME);

return 0;
}函式名: qsort
功能: 使用快速排序例程進行排序
用法: void qsort(void *base, int nelem, int width, int (*fcmp)());
程式例:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int sort_function( const void *a, const void *b);

char list[5][4] = { "cat", "car", "cab", "cap", "can" };

int main(void)
{
int x;

qsort((void *)list, 5, sizeof(list[0]), sort_function);
for (x = 0; x < 5; x++)
printf("%s\n", list[x]);
return 0;
}

int sort_function( const void *a, const void *b)
{
return( strcmp(a,b) );
} 函式名: raise
功能: 向正在執行的程式傳送一個訊號
用法: int raise(int sig);
程式例:

#include <signal.h>

int main(void)
{
int a, b;

a = 10;
b = 0;
if (b == 0)
/* preempt divide by zero error */
raise(SIGFPE);
a = a / b;
return 0;
}

函式名: rand
功能: 隨機數發生器
用法: void rand(void);
程式例:

#include <stdlib.h>
#include <stdio.h>

int main(void)
{
int i;

printf("Ten random numbers from 0 to 99\n\n");
for(i=0; i<10; i++)
printf("%d\n", rand() % 100);
return 0;
}

函式名: randbrd
功能: 隨機塊讀
用法: int randbrd(struct fcb *fcbptr, int reccnt);
程式例:

#include <process.h>
#include <string.h>
#include <stdio.h>
#include <dos.h>

int main(void)
{
char far *save_dta;
char line[80], buffer[256];
struct fcb blk;
int i, result;

/* get user input file name for dta */
printf("Enter drive and file name (no path - i.e. a:file.dat)\n");
gets(line);

/* put file name in fcb */
if (!parsfnm(line, &blk, 1))
{
printf("Error in call to parsfnm\n");
exit(1);
}
printf("Drive #%d File: %s\n\n", blk.fcb_drive, blk.fcb_name);

/* open file with DOS FCB open file */
bdosptr(0x0F, &blk, 0);

/* save old dta, and set new one */
save_dta = getdta();
setdta(buffer);

/* set up info for the new dta */
blk.fcb_recsize = 128;
blk.fcb_random = 0L;
result = randbrd(&blk, 1);

/* check results from randbrd */
if (!result)
printf("Read OK\n\n");
else
{
perror("Error during read");
exit(1);
}

/* read in data from the new dta */
printf("The first 128 characters are:\n");
for (i=0; i<128; i++)
putchar(buffer[i]);

/* restore previous dta */
setdta(save_dta);

return 0;
}

函式名: randbwr
功能: 隨機塊寫
用法: int randbwr(struct fcp *fcbptr, int reccnt);
程式例:

#include <process.h>
#include <string.h>
#include <stdio.h>
#include <dos.h>

int main(void)
{
char far *save_dta;
char line[80];
char buffer[256] = "RANDBWR test!";
struct fcb blk;
int result;

/* get new file name from user */
printf("Enter a file name to create (no path - ie. a:file.dat\n");
gets(line);

/* parse the new file name to the dta */
parsfnm(line,&blk,1);
printf("Drive #%d File: %s\n", blk.fcb_drive, blk.fcb_name);

/* request DOS services to create file */
if (bdosptr(0x16, &blk, 0) == -1)
{
perror("Error creating file");
exit(1);
}

/* save old dta and set new dta */
save_dta = getdta();
setdta(buffer);

/* write new records */
blk.fcb_recsize = 256;
blk.fcb_random = 0L;
result = randbwr(&blk, 1);

if (!result)
printf("Write OK\n");
else
{
perror("Disk error");
exit(1);
}

/* request DOS services to close the file */
if (bdosptr(0x10, &blk, 0) == -1)
{
perror("Error closing file");
exit(1);
}

/* reset the old dta */
setdta(save_dta);

return 0;
}

函式名: random
功能: 隨機數發生器
用法: int random(int num);
程式例:

#include <stdlib.h>
#include <stdio.h>
#include <time.h>

/* prints a random number in the range 0 to 99 */
int main(void)
{
randomize();
printf("Random number in the 0-99 range: %d\n", random (100));
return 0;
}

函式名: randomize
功能: 初始化隨機數發生器
用法: void randomize(void);
程式例:

#include <stdlib.h>
#include <stdio.h>
#include <time.h>

int main(void)
{
int i;

randomize();
printf("Ten random numbers from 0 to 99\n\n");
for(i=0; i<10; i++)
printf("%d\n", rand() % 100);
return 0;
}

函式名: read
功能: 從檔案中讀
用法: int read(int handle, void *buf, int nbyte);
程式例:

#include <stdio.h>
#include <io.h>
#include <alloc.h>
#include <fcntl.h>
#include <process.h>
#include <sys\stat.h>

int main(void)
{
void *buf;
int handle, bytes;

buf = malloc(10);

/*
Looks for a file in the current directory named TEST.$$$ and attempts
to read 10 bytes from it. To use this example you should create the
file TEST.$$$
*/
if ((handle =
open("TEST.$$$", O_RDONLY | O_BINARY, S_IWRITE | S_IREAD)) == -1)
{
printf("Error Opening File\n");
exit(1);
}

if ((bytes = read(handle, buf, 10)) == -1) {
printf("Read Failed.\n");
exit(1);
}
else {
printf("Read: %d bytes read.\n", bytes);
}
return 0;
}

函式名: realloc
功能: 重新分配主存
用法: void *realloc(void *ptr, unsigned newsize);
程式例:

#include <stdio.h>
#include <alloc.h>
#include <string.h>

int main(void)
{
char *str;

/* allocate memory for string */
str = malloc(10);

/* copy "Hello" into string */
strcpy(str, "Hello");

printf("String is %s\n Address is %p\n", str, str);
str = realloc(str, 20);
printf("String is %s\n New address is %p\n", str, str);

/* free memory */
free(str);

return 0;
}

函式名: rectangle
功能: 畫一個矩形
用法: void far rectangle(int left, int top, int right, int bottom);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int left, top, right, bottom;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

left = getmaxx() / 2 - 50;
top = getmaxy() / 2 - 50;
right = getmaxx() / 2 + 50;
bottom = getmaxy() / 2 + 50;

/* draw a rectangle */
rectangle(left,top,right,bottom);

/* clean up */
getch();
closegraph();
return 0;
}

函式名: registerbgidriver
功能: 登入已連線進來的圖形驅動程式程式碼
用法: int registerbgidriver(void(*driver)(void));
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;

/* register a driver that was added into graphics.lib */
errorcode = registerbgidriver(EGAVGA_driver);

/* report any registration errors */
if (errorcode < 0)
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

/* draw a line */
line(0, 0, getmaxx(), getmaxy());

/* clean up */
getch();
closegraph();
return 0;
}

函式名: remove
功能: 刪除一個檔案
用法: int remove(char *filename);
程式例:

#include <stdio.h>

int main(void)
{
char file[80];

/* prompt for file name to delete */
printf("File to delete: ");
gets(file);

/* delete the file */
if (remove(file) == 0)
printf("Removed %s.\n",file);
else
perror("remove");

return 0;
}

函式名: rename
功能: 重新命名檔案
用法: int rename(char *oldname, char *newname);
程式例:

#include <stdio.h>

int main(void)
{
char oldname[80], newname[80];

/* prompt for file to rename and new name */
printf("File to rename: ");
gets(oldname);
printf("New name: ");
gets(newname);

/* Rename the file */
if (rename(oldname, newname) == 0)
printf("Renamed %s to %s.\n", oldname, newname);
else
perror("rename");

return 0;
}

函式名: restorecrtmode
功能: 將螢幕模式恢復為先前的imitgraph設定
用法: void far restorecrtmode(void);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int x, y;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

x = getmaxx() / 2;
y = getmaxy() / 2;

/* output a message */
settextjustify(CENTER_TEXT, CENTER_TEXT);
outtextxy(x, y, "Press any key to exit graphics:");
getch();

/* restore system to text mode */
restorecrtmode();
printf("We're now in text mode.\n");
printf("Press any key to return to graphics mode:");
getch();

/* return to graphics mode */
setgraphmode(getgraphmode());

/* output a message */
settextjustify(CENTER_TEXT, CENTER_TEXT);
outtextxy(x, y, "We're back in graphics mode.");
outtextxy(x, y+textheight("W"), "Press any key to halt:");

/* clean up */
getch();
closegraph();
return 0;
}

函式名: rewind
功能: 將檔案指標重新指向一個流的開頭
用法: int rewind(FILE *stream);
程式例:

#include <stdio.h>
#include <dir.h>

int main(void)
{
FILE *fp;
char *fname = "TXXXXXX", *newname, first;

newname = mktemp(fname);
fp = fopen(newname,"w+");
fprintf(fp,"abcdefghijklmnopqrstuvwxyz");
rewind(fp);
fscanf(fp,"%c",&first);
printf("The first character is: %c\n",first);
fclose(fp);
remove(newname);

return 0;
}

函式名: rmdir
功能: 刪除DOS檔案目錄
用法: int rmdir(char *stream);
程式例:

#include <stdio.h>
#include <conio.h>
#include <process.h>
#include <dir.h>

#define DIRNAME "testdir.$$$"

int main(void)
{
int stat;

stat = mkdir(DIRNAME);
if (!stat)
printf("Directory created\n");
else
{
printf("Unable to create directory\n");
exit(1);
}

getch();
system("dir/p");
getch();

stat = rmdir(DIRNAME);
if (!stat)
printf("\nDirectory deleted\n");
else
{
perror("\nUnable to delete directory\n");
exit(1);
}

return 0;
}
函式名: sbrk
功能: 改變資料段空間位置
用法: char *sbrk(int incr);
程式例:

#include <stdio.h>
#include <alloc.h>

int main(void)
{
printf("Changing allocation with sbrk()\n");
printf("Before sbrk() call: %lu bytes free\n",
(unsigned long) coreleft());
sbrk(1000);
printf(" After sbrk() call: %lu bytes free\n",
(unsigned long) coreleft());
return 0;
}

函式名: scanf
功能: 執行格式化輸入
用法: int scanf(char *format[,argument,...]);
程式例:

#include <stdio.h>
#include <conio.h>

int main(void)
{
char label[20];
char name[20];
int entries = 0;
int loop, age;
double salary;

struct Entry_struct
{
char name[20];
int age;
float salary;
} entry[20];

/* Input a label as a string of characters restricting to 20 characters */
printf("\n\nPlease enter a label for the chart: ");
scanf("%20s", label);
fflush(stdin); /* flush the input stream in case of bad input */

/* Input number of entries as an integer */
printf("How many entries will there be? (less than 20) ");
scanf("%d", &entries);
fflush(stdin); /* flush the input stream in case of bad input */

/* input a name restricting input to only letters upper or lower case */
for (loop=0;loop<entries;++loop)
{
printf("Entry %d\n", loop);
printf(" Name : ");
scanf("%[A-Za-z]", entry[loop].name);
fflush(stdin); /* flush the input stream in case of bad input */

/* input an age as an integer */
printf(" Age : ");
scanf("%d", &entry[loop].age);
fflush(stdin); /* flush the input stream in case of bad input */

/* input a salary as a float */
printf(" Salary : ");
scanf("%f", &entry[loop].salary);
fflush(stdin); /* flush the input stream in case of bad input */
}

/* Input a name, age and salary as a string, integer, and double */
printf("\nPlease enter your name, age and salary\n");
scanf("%20s %d %lf", name, &age, &salary);

/* Print out the data that was input */
printf("\n\nTable %s\n",label);
printf("Compiled by %s age %d $%15.2lf\n", name, age, salary);
printf("-----------------------------------------------------\n");
for (loop=0;loop<entries;++loop)
printf("%4d | %-20s | %5d | %15.2lf\n",
loop + 1,
entry[loop].name,
entry[loop].age,
entry[loop].salary);
printf("-----------------------------------------------------\n");
return 0;
}

函式名: searchpath
功能: 搜尋DOS路徑
用法: char *searchpath(char *filename);
程式例:

#include <stdio.h>
#include <dir.h>

int main(void)
{
char *p;

/* Looks for TLINK and returns a pointer
to the path */
p = searchpath("TLINK.EXE");
printf("Search for TLINK.EXE : %s\n", p);

/* Looks for non-existent file */
p = searchpath("NOTEXIST.FIL");
printf("Search for NOTEXIST.FIL : %s\n", p);

return 0;
}

函式名: sector
功能: 畫並填充橢圓扇區
用法: void far sector(int x, int y, int stangle, int endangle);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int midx, midy, i;
int stangle = 45, endangle = 135;
int xrad = 100, yrad = 50;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

midx = getmaxx() / 2;
midy = getmaxy() / 2;

/* loop through the fill patterns */
for (i=EMPTY_FILL; i<USER_FILL; i++)
{
/* set the fill style */
setfillstyle(i, getmaxcolor());

/* draw the sector slice */
sector(midx, midy, stangle, endangle, xrad, yrad);

getch();
}

/* clean up */
closegraph();
return 0;
}

函式名: segread
功能: 讀段暫存器值
用法: void segread(struct SREGS *segtbl);
程式例:

#include <stdio.h>
#include <dos.h>

int main(void)
{
struct SREGS segs;

segread(&segs);
printf("Current segment register settings\n\n");
printf("CS: %X DS: %X\n", segs.cs, segs.ds);
printf("ES: %X SS: %X\n", segs.es, segs.ss);

return 0;
}

函式名: setactivepage
功能: 設定圖形輸出活動頁
用法: void far setactivepage(int pagenum);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* select a driver and mode that supports */
/* multiple pages. */
int gdriver = EGA, gmode = EGAHI, errorcode;
int x, y, ht;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

x = getmaxx() / 2;
y = getmaxy() / 2;
ht = textheight("W");

/* select the off screen page for drawing */
setactivepage(1);

/* draw a line on page #1 */
line(0, 0, getmaxx(), getmaxy());

/* output a message on page #1 */
settextjustify(CENTER_TEXT, CENTER_TEXT);
outtextxy(x, y, "This is page #1:");
outtextxy(x, y+ht, "Press any key to halt:");

/* select drawing to page #0 */
setactivepage(0);

/* output a message on page #0 */
outtextxy(x, y, "This is page #0.");
outtextxy(x, y+ht, "Press any key to view page #1:");
getch();

/* select page #1 as the visible page */
setvisualpage(1);

/* clean up */
getch();
closegraph();
return 0;
}

函式名: setallpallette
功能: 按指定方式改變所有的調色盤顏色
用法: void far setallpallette(struct palette, far *pallette);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
struct palettetype pal;
int color, maxcolor, ht;
int y = 10;
char msg[80];

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

maxcolor = getmaxcolor();
ht = 2 * textheight("W");

/* grab a copy of the palette */
getpalette(&pal);

/* display the default palette colors */
for (color=1; color<=maxcolor; color++)
{
setcolor(color);
sprintf(msg, "Color: %d", color);
outtextxy(1, y, msg);
y += ht;
}

/* wait for a key */
getch();

/* black out the colors one by one */
for (color=1; color<=maxcolor; color++)
{
setpalette(color, BLACK);
getch();
}

/* restore the palette colors */
setallpalette(&pal);

/* clean up */
getch();
closegraph();
return 0;
}

函式名: setaspectratio
功能: 設定圖形縱橫比
用法: void far setaspectratio(int xasp, int yasp);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int xasp, yasp, midx, midy;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

midx = getmaxx() / 2;
midy = getmaxy() / 2;
setcolor(getmaxcolor());

/* get current aspect ratio settings */
getaspectratio(&xasp, &yasp);

/* draw normal circle */
circle(midx, midy, 100);
getch();

/* claer the screen */
cleardevice();

/* adjust the aspect for a wide circle */
setaspectratio(xasp/2, yasp);
circle(midx, midy, 100);
getch();

/* adjust the aspect for a narrow circle */
cleardevice();
setaspectratio(xasp, yasp/2);
circle(midx, midy, 100);

/* clean up */
getch();
closegraph();
return 0;
}

函式名: setbkcolor
功能: 用調色盤設定當前背景顏色
用法: void far setbkcolor(int color);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* select a driver and mode that supports */
/* multiple background colors. */
int gdriver = EGA, gmode = EGAHI, errorcode;
int bkcol, maxcolor, x, y;
char msg[80];

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

/* maximum color index supported */
maxcolor = getmaxcolor();

/* for centering text messages */
settextjustify(CENTER_TEXT, CENTER_TEXT);
x = getmaxx() / 2;
y = getmaxy() / 2;

/* loop through the available colors */
for (bkcol=0; bkcol<=maxcolor; bkcol++)
{
/* clear the screen */
cleardevice();

/* select a new background color */
setbkcolor(bkcol);

/* output a messsage */
if (bkcol == WHITE)
setcolor(EGA_BLUE);
sprintf(msg, "Background color: %d", bkcol);
outtextxy(x, y, msg);
getch();
}

/* clean up */
closegraph();
return 0;
}

函式名: setblock
功能: 修改先前已分配的DOS儲存段大小
用法: int setblock(int seg, int newsize);
程式例:

#include <dos.h>
#include <alloc.h>
#include <stdio.h>
#include <stdlib.h>

int main(void)
{
unsigned int size, segp;
int stat;

size = 64; /* (64 x 16) = 1024 bytes */
stat = allocmem(size, &segp);
if (stat == -1)
printf("Allocated memory at segment: %X\n", segp);
else
{
printf("Failed: maximum number of paragraphs available is %d\n",
stat);
exit(1);
}

stat = setblock(segp, size * 2);
if (stat == -1)
printf("Expanded memory block at segment: %X\n", segp);
else
printf("Failed: maximum number of paragraphs available is %d\n",
stat);

freemem(segp);

return 0;
}

函式名: setbuf
功能: 把緩衝區與流相聯
用法: void setbuf(FILE *steam, char *buf);
程式例:

#include <stdio.h>

/* BUFSIZ is defined in stdio.h */
char outbuf[BUFSIZ];

int main(void)
{
/* attach a buffer to the standard output stream */
setbuf(stdout, outbuf);

/* put some characters into the buffer */
puts("This is a test of buffered output.\n\n");
puts("This output will go into outbuf\n");
puts("and won't appear until the buffer\n");
puts("fills up or we flush the stream.\n");

/* flush the output buffer */
fflush(stdout);

return 0;
}

函式名: setcbrk
功能: 設定Control-break
用法: int setcbrk(int value);
程式例:

#include <dos.h>
#include <conio.h>
#include <stdio.h>

int main(void)
{
int break_flag;

printf("Enter 0 to turn control break off\n");
printf("Enter 1 to turn control break on\n");

break_flag = getch() - 0;

setcbrk(break_flag);

if (getcbrk())
printf("Cntrl-brk flag is on\n");
else
printf("Cntrl-brk flag is off\n");
return 0;
}

函式名: setcolor
功能: 設定當前畫線顏色
用法: void far setcolor(int color);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* select a driver and mode that supports */
/* multiple drawing colors. */
int gdriver = EGA, gmode = EGAHI, errorcode;
int color, maxcolor, x, y;
char msg[80];

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

/* maximum color index supported */
maxcolor = getmaxcolor();

/* for centering text messages */
settextjustify(CENTER_TEXT, CENTER_TEXT);
x = getmaxx() / 2;
y = getmaxy() / 2;

/* loop through the available colors */
for (color=1; color<=maxcolor; color++)
{
/* clear the screen */
cleardevice();

/* select a new background color */
setcolor(color);

/* output a messsage */
sprintf(msg, "Color: %d", color);
outtextxy(x, y, msg);
getch();
}

/* clean up */
closegraph();
return 0;
}

函式名: setdate
功能: 設定DOS日期
用法: void setdate(struct date *dateblk);
程式例:

#include <stdio.h>
#include <process.h>
#include <dos.h>

int main(void)
{
struct date reset;
struct date save_date;

getdate(&save_date);
printf("Original date:\n");
system("date");

reset.da_year = 2001;
reset.da_day = 1;
reset.da_mon = 1;
setdate(&reset);

printf("Date after setting:\n");
system("date");

setdate(&save_date);
printf("Back to original date:\n");
system("date");

return 0;
}

函式名: setdisk
功能: 設定當前磁碟驅動器
用法: int setdisk(int drive);
程式例:

#include <stdio.h>
#include <dir.h>

int main(void)
{
int save, disk, disks;

/* save original drive */
save = getdisk();

/* print number of logic drives */
disks = setdisk(save);
printf("%d logical drives on the system\n\n", disks);

/* print the drive letters available */
printf("Available drives:\n");
for (disk = 0;disk < 26;++disk)
{
setdisk(disk);
if (disk == getdisk())
printf("%c: drive is available\n", disk + 'a');
}
setdisk(save);

return 0;
}

函式名: setdta
功能: 設定磁碟傳輸區地址
用法: void setdta(char far *dta);
程式例:

#include <process.h>
#include <string.h>
#include <stdio.h>
#include <dos.h>

int main(void)
{
char line[80], far *save_dta;
char buffer[256] = "SETDTA test!";
struct fcb blk;
int result;

/* get new file name from user */
printf("Enter a file name to create:");
gets(line);

/* parse the new file name to the dta */
parsfnm(line, &blk, 1);
printf("%d %s\n", blk.fcb_drive, blk.fcb_name);

/* request DOS services to create file */
if (bdosptr(0x16, &blk, 0) == -1)
{
perror("Error creating file");
exit(1);
}

/* save old dta and set new dta */
save_dta = getdta();
setdta(buffer);

/* write new records */
blk.fcb_recsize = 256;
blk.fcb_random = 0L;
result = randbwr(&blk, 1);
printf("result = %d\n", result);

if (!result)
printf("Write OK\n");
else
{
perror("Disk error");
exit(1);
}

/* request DOS services to close the file */
if (bdosptr(0x10, &blk, 0) == -1)
{
perror("Error closing file");
exit(1);
}

/* reset the old dta */
setdta(save_dta);
return 0;
}

函式名: setfillpattern
功能: 選擇使用者定義的填充模式
用法: void far setfillpattern(char far *upattern, int color);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int maxx, maxy;

/* a user defined fill pattern */
char pattern[8] = {0x00, 0x70, 0x20, 0x27, 0x24, 0x24, 0x07, 0x00};

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

maxx = getmaxx();
maxy = getmaxy();
setcolor(getmaxcolor());

/* select a user defined fill pattern */
setfillpattern(pattern, getmaxcolor());

/* fill the screen with the pattern */
bar(0, 0, maxx, maxy);

/* clean up */
getch();
closegraph();
return 0;
}

函式名: setfillstyle
功能: 設定填充模式和顏色
用法: void far setfillstyle(int pattern, int color);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <conio.h>

/* the names of the fill styles supported */
char *fname[] = { "EMPTY_FILL",
"SOLID_FILL",
"LINE_FILL",
"LTSLASH_FILL",
"SLASH_FILL",
"BKSLASH_FILL",
"LTBKSLASH_FILL",
"HATCH_FILL",
"XHATCH_FILL",
"INTERLEAVE_FILL",
"WIDE_DOT_FILL",
"CLOSE_DOT_FILL",
"USER_FILL"
};

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int style, midx, midy;
char stylestr[40];

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

midx = getmaxx() / 2;
midy = getmaxy() / 2;

for (style = EMPTY_FILL; style < USER_FILL; style++)
{
/* select the fill style */
setfillstyle(style, getmaxcolor());

/* convert style into a string */
strcpy(stylestr, fname[style]);

/* fill a bar */
bar3d(0, 0, midx-10, midy, 0, 0);

/* output a message */
outtextxy(midx, midy, stylestr);

/* wait for a key */
getch();
cleardevice();
}

/* clean up */
getch();
closegraph();
return 0;
}

函式名: setftime
功能: 設定檔案日期和時間
用法: int setftime(int handle, struct ftime *ftimep);
程式例:

#include <stdio.h>
#include <process.h>
#include <fcntl.h>
#include <io.h>

int main(void)
{
struct ftime filet;
FILE *fp;

if ((fp = fopen("TEST.$$$", "w")) == NULL)
{
perror("Error:");
exit(1);
}

fprintf(fp, "testing...\n");

/* load ftime structure with new time and date */
filet.ft_tsec = 1;
filet.ft_min = 1;
filet.ft_hour = 1;
filet.ft_day = 1;
filet.ft_month = 1;
filet.ft_year = 21;

/* show current directory for time and date */
system("dir TEST.$$$");

/* change the time and date stamp*/
setftime(fileno(fp), &filet);

/* close and remove the temporary file */
fclose(fp);

system("dir TEST.$$$");

unlink("TEST.$$$");
return 0;
}

函式名: setgraphbufsize
功能: 改變內部圖形緩衝區的大小
用法: unsigned far setgraphbufsize(unsigned bufsize);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

#define BUFSIZE 1000 /* internal graphics buffer size */

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int x, y, oldsize;
char msg[80];

/* set the size of the internal graphics buffer */
/* before making a call to initgraph. */
oldsize = setgraphbufsize(BUFSIZE);

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

x = getmaxx() / 2;
y = getmaxy() / 2;

/* output some messages */
sprintf(msg, "Graphics buffer size: %d", BUFSIZE);
settextjustify(CENTER_TEXT, CENTER_TEXT);
outtextxy(x, y, msg);
sprintf(msg, "Old graphics buffer size: %d", oldsize);
outtextxy(x, y+textheight("W"), msg);

/* clean up */
getch();
closegraph();
return 0;
}

函式名: setgraphmode
功能: 將系統設定成圖形模式且清屏
用法: void far setgraphmode(int mode);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int x, y;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

x = getmaxx() / 2;
y = getmaxy() / 2;

/* output a message */
settextjustify(CENTER_TEXT, CENTER_TEXT);
outtextxy(x, y, "Press any key to exit graphics:");
getch();

/* restore system to text mode */
restorecrtmode();
printf("We're now in text mode.\n");
printf("Press any key to return to graphics mode:");
getch();

/* return to graphics mode */
setgraphmode(getgraphmode());

/* output a message */
settextjustify(CENTER_TEXT, CENTER_TEXT);
outtextxy(x, y, "We're back in graphics mode.");
outtextxy(x, y+textheight("W"), "Press any key to halt:");

/* clean up */
getch();
closegraph();
return 0;
}
函式名: setjmp
功能: 非區域性轉移
用法: int setjmp(jmp_buf env);
程式例:

#include <stdio.h>
#include <process.h>
#include <setjmp.h>

void subroutine(void);

jmp_buf jumper;

int main(void)
{
int value;

value = setjmp(jumper);
if (value != 0)
{
printf("Longjmp with value %d\n", value);
exit(value);
}
printf("About to call subroutine ... \n");
subroutine();
return 0;
}

void subroutine(void)
{
longjmp(jumper,1);
}

函式名: setlinestyle
功能: 設定當前畫線寬度和型別
用法: void far setlinestyle(int linestype, unsigned upattern);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <conio.h>

/* the names of the line styles supported */
char *lname[] = {
"SOLID_LINE",
"DOTTED_LINE",
"CENTER_LINE",
"DASHED_LINE",
"USERBIT_LINE"
};

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;

int style, midx, midy, userpat;
char stylestr[40];

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

midx = getmaxx() / 2;
midy = getmaxy() / 2;

/* a user defined line pattern */
/* binary: "0000000000000001" */
userpat = 1;

for (style=SOLID_LINE; style<=USERBIT_LINE; style++)
{
/* select the line style */
setlinestyle(style, userpat, 1);

/* convert style into a string */
strcpy(stylestr, lname[style]);

/* draw a line */
line(0, 0, midx-10, midy);

/* draw a rectangle */
rectangle(0, 0, getmaxx(), getmaxy());

/* output a message */
outtextxy(midx, midy, stylestr);

/* wait for a key */
getch();
cleardevice();
}

/* clean up */
closegraph();
return 0;
}

函式名: setmem
功能: 存值到儲存區
用法: void setmem(void *addr, int len, char value);
程式例:

#include <stdio.h>
#include <alloc.h>
#include <mem.h>

int main(void)
{
char *dest;

dest = calloc(21, sizeof(char));
setmem(dest, 20, 'c');
printf("%s\n", dest);

return 0;
}

函式名: setmode
功能: 設定開啟檔案方式
用法: int setmode(int handle, unsigned mode);
程式例:

#include <stdio.h>
#include <fcntl.h>
#include <io.h>

int main(void)
{
int result;

result = setmode(fileno(stdprn), O_TEXT);
if (result == -1)
perror("Mode not available\n");
else
printf("Mode successfully switched\n");
return 0;
}

函式名: setpalette
功能: 改變調色盤的顏色
用法: void far setpalette(int index, int actural_color);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int color, maxcolor, ht;
int y = 10;
char msg[80];

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

maxcolor = getmaxcolor();
ht = 2 * textheight("W");

/* display the default colors */
for (color=1; color<=maxcolor; color++)
{
setcolor(color);
sprintf(msg, "Color: %d", color);
outtextxy(1, y, msg);
y += ht;
}

/* wait for a key */
getch();

/* black out the colors one by one */
for (color=1; color<=maxcolor; color++)
{
setpalette(color, BLACK);
getch();
}

/* clean up */
closegraph();
return 0;
}

函式名: setrgbpalette
功能: 定義IBM8514圖形卡的顏色
用法: void far setrgbpalette(int colornum, int red, int green, int blue);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* select a driver and mode that supports the use */
/* of the setrgbpalette function. */
int gdriver = VGA, gmode = VGAHI, errorcode;
struct palettetype pal;
int i, ht, y, xmax;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

/* grab a copy of the palette */
getpalette(&pal);

/* create gray scale */
for (i=0; i<pal.size; i++)
setrgbpalette(pal.colors[i], i*4, i*4, i*4);

/* display the gray scale */
ht = getmaxy() / 16;
xmax = getmaxx();
y = 0;
for (i=0; i<pal.size; i++)
{
setfillstyle(SOLID_FILL, i);
bar(0, y, xmax, y+ht);
y += ht;
}

/* clean up */
getch();
closegraph();
return 0;
}

函式名: settextjustify
功能: 為圖形函式設定文字的對齊方式
用法: void far settextjustify(int horiz, int vert);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

/* function prototype */
void xat(int x, int y);

/* horizontal text justification settings */
char *hjust[] = { "LEFT_TEXT",
"CENTER_TEXT",
"RIGHT_TEXT"
};

/* vertical text justification settings */
char *vjust[] = { "LEFT_TEXT",
"CENTER_TEXT",
"RIGHT_TEXT"
};

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int midx, midy, hj, vj;
char msg[80];

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

midx = getmaxx() / 2;
midy = getmaxy() / 2;

/* loop through text justifications */
for (hj=LEFT_TEXT; hj<=RIGHT_TEXT; hj++)
for (vj=LEFT_TEXT; vj<=RIGHT_TEXT; vj++)
{
cleardevice();
/* set the text justification */
settextjustify(hj, vj);

/* create a message string */
sprintf(msg, "%s %s", hjust[hj], vjust[vj]);

/* create cross hairs on the screen */
xat(midx, midy);

/* output the message */
outtextxy(midx, midy, msg);
getch();
}

/* clean up */
closegraph();
return 0;
}

/* draw an "x" at (x, y) */
void xat(int x, int y)
{
line(x-4, y, x+4, y);
line(x, y-4, x, y+4);
}

函式名: settextstyle
功能: 為圖形輸出設定當前的文字屬性
用法: void far settextstyle (int font, int direction, char size);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

/* the names of the text styles supported */
char *fname[] = { "DEFAULT font",
"TRIPLEX font",
"SMALL font",
"SANS SERIF font",
"GOTHIC font"
};

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int style, midx, midy;
int size = 1;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

midx = getmaxx() / 2;
midy = getmaxy() / 2;

settextjustify(CENTER_TEXT, CENTER_TEXT);

/* loop through the available text styles */
for (style=DEFAULT_FONT; style<=GOTHIC_FONT; style++)
{
cleardevice();
if (style == TRIPLEX_FONT)
size = 4;

/* select the text style */
settextstyle(style, HORIZ_DIR, size);

/* output a message */
outtextxy(midx, midy, fname[style]);
getch();
}

/* clean up */
closegraph();
return 0;
}

函式名: settextstyle
功能: 為圖形輸出設定當前的文字屬性
用法: void far settextstyle (int font, int direction, char size);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

/* the names of the text styles supported */
char *fname[] = { "DEFAULT font",
"TRIPLEX font",
"SMALL font",
"SANS SERIF font",
"GOTHIC font"
};

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int style, midx, midy;
int size = 1;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

midx = getmaxx() / 2;
midy = getmaxy() / 2;

settextjustify(CENTER_TEXT, CENTER_TEXT);

/* loop through the available text styles */
for (style=DEFAULT_FONT; style<=GOTHIC_FONT; style++)
{
cleardevice();
if (style == TRIPLEX_FONT)
size = 4;

/* select the text style */
settextstyle(style, HORIZ_DIR, size);

/* output a message */
outtextxy(midx, midy, fname[style]);
getch();
}

/* clean up */
closegraph();
return 0;
}

函式名: settime
功能: 設定系統時間
用法: void settime(struct time *timep);
程式例:

#include <stdio.h>
#include <dos.h>

int main(void)
{
struct time t;

gettime(&t);
printf("The current minute is: %d\n", t.ti_min);
printf("The current hour is: %d\n", t.ti_hour);
printf("The current hundredth of a second is: %d\n", t.ti_hund);
printf("The current second is: %d\n", t.ti_sec);

/* Add one to the minutes struct element and then call settime */
t.ti_min++;
settime(&t);

return 0;
}

函式名: setusercharsize
功能: 為向量字型改變字元寬度和高度
用法: void far setusercharsize(int multx, int dirx, int multy, int diry);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* request autodetection */
int gdriver = DETECT, gmode, errorcode;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

/* select a text style */
settextstyle(TRIPLEX_FONT, HORIZ_DIR, 4);

/* move to the text starting position */
moveto(0, getmaxy() / 2);

/* output some normal text */
outtext("Norm ");

/* make the text 1/3 the normal width */
setusercharsize(1, 3, 1, 1);
outtext("Short ");

/* make the text 3 times normal width */
setusercharsize(3, 1, 1, 1);
outtext("Wide");

/* clean up */
getch();
closegraph();
return 0;
}

函式名: setvbuf
功能: 把緩衝區與流相關
用法: int setvbuf(FILE *stream, char *buf, int type, unsigned size);
程式例:

#include <stdio.h>

int main(void)
{
FILE *input, *output;
char bufr[512];

input = fopen("file.in", "r+b");
output = fopen("file.out", "w");

/* set up input stream for minimal disk access,
using our own character buffer */
if (setvbuf(input, bufr, _IOFBF, 512) != 0)
printf("failed to set up buffer for input file\n");
else
printf("buffer set up for input file\n");

/* set up output stream for line buffering using space that
will be obtained through an indirect call to malloc */
if (setvbuf(output, NULL, _IOLBF, 132) != 0)
printf("failed to set up buffer for output file\n");
else
printf("buffer set up for output file\n");

/* perform file I/O here */

/* close files */
fclose(input);
fclose(output);
return 0;
}

函式名: setvect
功能: 設定中斷向量入口
用法: void setvect(int intr_num, void interrupt(*isr)());
程式例:

/***NOTE:
This is an interrupt service routine. You can NOT compile this
program with Test Stack Overflow turned on and get an executable
file which will operate correctly. */

#include <stdio.h>
#include <dos.h>
#include <conio.h>

#define INTR 0X1C /* The clock tick interrupt */

void interrupt ( *oldhandler)(void);

int count=0;

void interrupt handler(void)
{
/* increase the global counter */
count++;

/* call the old routine */
oldhandler();
}

int main(void)
{
/* save the old interrupt vector */
oldhandler = getvect(INTR);

/* install the new interrupt handler */
setvect(INTR, handler);

/* loop until the counter exceeds 20 */
while (count < 20)
printf("count is %d\n",count);

/* reset the old interrupt handler */
setvect(INTR, oldhandler);

return 0;
}

函式名: setverify
功能: 設定驗證狀態
用法: void setverify(int value);
程式例:

#include <stdio.h>
#include <conio.h>
#include <dos.h>

int main(void)
{
int verify_flag;

printf("Enter 0 to set verify flag off\n");
printf("Enter 1 to set verify flag on\n");

verify_flag = getch() - 0;

setverify(verify_flag);

if (getverify())
printf("DOS verify flag is on\n");
else
printf("DOS verify flag is off\n");

return 0;
}

函式名: setviewport
功能: 為圖形輸出設定當前視口
用法: void far setviewport(int left, int top, int right,
int bottom, int clipflag);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

#define CLIP_ON 1 /* activates clipping in viewport */

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

setcolor(getmaxcolor());

/* message in default full-screen viewport */
outtextxy(0, 0, "* <-- (0, 0) in default viewport");

/* create a smaller viewport */
setviewport(50, 50, getmaxx()-50, getmaxy()-50, CLIP_ON);

/* display some text */
outtextxy(0, 0, "* <-- (0, 0) in smaller viewport");

/* clean up */
getch();
closegraph();
return 0;
}

函式名: setvisualpage
功能: 設定可見圖形頁號
用法: void far setvisualpage(int pagenum);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
/* select a driver and mode that supports */
/* multiple pages. */
int gdriver = EGA, gmode = EGAHI, errorcode;
int x, y, ht;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

x = getmaxx() / 2;
y = getmaxy() / 2;
ht = textheight("W");

/* select the off screen page for drawing */
setactivepage(1);

/* draw a line on page #1 */
line(0, 0, getmaxx(), getmaxy());

/* output a message on page #1 */
settextjustify(CENTER_TEXT, CENTER_TEXT);
outtextxy(x, y, "This is page #1:");
outtextxy(x, y+ht, "Press any key to halt:");

/* select drawing to page #0 */
setactivepage(0);

/* output a message on page #0 */
outtextxy(x, y, "This is page #0.");
outtextxy(x, y+ht, "Press any key to view page #1:");
getch();

/* select page #1 as the visible page */
setvisualpage(1);

/* clean up */
getch();
closegraph();
return 0;
}

函式名: setwritemode
功能: 設定圖形方式下畫線的輸出模式
用法: void far setwritemode(int mode);
程式例:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main()
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int xmax, ymax;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}

xmax = getmaxx();
ymax = getmaxy();

/* select XOR drawing mode */
setwritemode(XOR_PUT);

/* draw a line */
line(0, 0, xmax, ymax);
getch();

/* erase the line by drawing over it */
line(0, 0, xmax, ymax);
getch();

/* select overwrite drawing mode */
setwritemode(COPY_PUT);

/* draw a line */
line(0, 0, xmax, ymax);

/* clean up */
getch();
closegraph();
return 0;
}

函式名: signal
功能: 設定某一訊號的對應動作
用法: int signal(int sig, sigfun fname);
程式例:

/* This example installs a signal handler routine for SIGFPE,
catches an integer overflow condition, makes an adjustment
to AX register, and returns. This example program MAY cause
your computer to crash, and will produce runtime errors
depending on which memory model is used.
*/

#pragma inline
#include <stdio.h>
#include <signal.h>

void Catcher(int sig, int type, int *reglist)
{
printf("Caught it!\n");
*(reglist + 8) = 3; /* make return AX = 3 */
}

int main(void)
{
signal(SIGFPE, Catcher);
asm mov ax,07FFFH /* AX = 32767 */
asm inc ax /* cause overflow */
asm into /* activate handler */

/* The handler set AX to 3 on return. If that hadn't happened,
there would have been another exception when the next 'into'
was executed after the 'dec' instruction. */
asm dec ax /* no overflow now */
asm into /* doesn't activate */
return 0;
}

函式名: sin
功能: 正弦函式
用法: double sin(double x);
程式例:

#include <stdio.h>
#include <math.h>

int main(void)
{
double result, x = 0.5;

result = sin(x);
printf("The sin() of %lf is %lf\n", x, result);
return 0;
}

函式名: sinh
功能: 雙曲正弦函式
用法: double sinh(double x);
程式例:

#include <stdio.h>
#include <math.h>

int main(void)
{
double result, x = 0.5;

result = sinh(x);
printf("The hyperbolic sin() of %lf is %lf\n", x, result);
return 0;
}

函式名: sleep
功能: 執行掛起一段時間
用法: unsigned sleep(unsigned seconds);
程式例:

#include <dos.h>
#include <stdio.h>

int main(void)
{
int i;

for (i=1; i<5; i++)
{
printf("Sleeping for %d seconds\n", i);
sleep(i);
}
return 0;
}

函式名: sopen
功能: 開啟一共享檔案
用法: int sopen(char *pathname, int access, int shflag, int permiss);
程式例:

#include <io.h>
#include <fcntl.h>
#include <sys\stat.h>
#include <process.h>
#include <share.h>
#include <stdio.h>

int main(void)
{
int handle;
int status;

handle = sopen("c:\\autoexec.bat", O_RDONLY, SH_DENYNO, S_IREAD);

if (!handle)
{
printf("sopen failed\n");
exit(1);
}

status = access("c:\\autoexec.bat", 6);
if (status == 0)
printf("read/write access allowed\n");
else
printf("read/write access not allowed\n");

close(handle);
return 0;
} 函式名: sound
功能: 以指定頻率開啟PC揚聲器
用法: void sound(unsigned frequency);
程式例:

/* Emits a 7-Hz tone for 10 seconds.
Your PC may not be able to emit a 7-Hz tone. */
#include <dos.h>

int main(void)
{
sound(7);
delay(10000);
nosound();
return 0;
}

函式名: spawnl
功能: 建立並執行子程式
用法: int spawnl(int mode, char *pathname, char *arg0,
arg1, ... argn, NULL);
程式例:

#include <process.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
int result;

clrscr();
result = spawnl(P_WAIT, "tcc.exe", NULL);
if (result == -1)
{
perror("Error from spawnl");
exit(1);
}
return 0;
}

函式名: spawnle
功能: 建立並執行子程式
用法: int spawnle(int mode, char *pathname, char *arg0,
arg1,..., argn, NULL);
程式例:

/* spawnle() example */

#include <process.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
int result;

clrscr();
result = spawnle(P_WAIT, "tcc.exe", NULL, NULL);
if (result == -1)
{
perror("Error from spawnle");
exit(1);
}
return 0;
}

函式名: sprintf
功能: 送格式化輸出到字串中
用法: int sprintf(char *string, char *farmat [,argument,...]);
程式例:

#include <stdio.h>
#include <math.h>

int main(void)
{
char buffer[80];

sprintf(buffer, "An approximation of Pi is %f\n", M_PI);
puts(buffer);
return 0;
}

函式名: sqrt
功能: 計算平方根
用法: double sqrt(double x);
程式例:

#include <math.h>
#include <stdio.h>

int main(void)
{
double x = 4.0, result;

result = sqrt(x);
printf("The square root of %lf is %lf\n", x, result);
return 0;
}

函式名: srand
功能: 初始化隨機數發生器
用法: void srand(unsigned seed);
程式例:

#include <stdlib.h>
#include <stdio.h>
#include <time.h>

int main(void)
{
int i;
time_t t;

srand((unsigned) time(&t));
printf("Ten random numbers from 0 to 99\n\n");
for(i=0; i<10; i++)
printf("%d\n", rand() % 100);
return 0;
}

函式名: sscanf
功能: 執行從字串中的格式化輸入
用法: int sscanf(char *string, char *format[,argument,...]);
程式例: