Linux C 字串函式的總結

lcy_ltpsr發表於2016-07-16

Linux C 字串函式的總結

總結一下Linux平臺下,C語言處理字串的函式:

/*
* 函式名: stpcpy 
* 功   能: 拷貝一個字串到另一個 
* 用   法: char *stpcpy(char *destin, char *source); 
* 程式例:
*/
#include <stdio.h> 
#include <string.h>
int main(void) 
{ 
    char string[10]; 
    char *str1 = "abcdefghi";
    stpcpy(string, str1); 
    printf("%s\n", string); 
    return 0; 
} 
  
/*  
* 函式名: strcat 
* 功   能: 字串拼接函式 
* 用   法: char *strcat(char *destin, char *source); 
* 程式例:
*/
#include <string.h> 
#include <stdio.h>
int main(void) 
{ 
    char destination[25]; 
    char *blank = " ", *c = "C++", *Borland = "Borland";
    strcpy(destination, Borland); 
    strcat(destination, blank); 
    strcat(destination, c);
    printf("%s\n", destination); 
    return 0; 
} 
  
/*   
* 函式名: strchr 
* 功   能: 在一個串中查詢給定字元的第一個匹配之處\ 
* 用   法: char *strchr(char *str, char c); 
* 程式例:
*/
#include <string.h> 
#include <stdio.h>
int main(void) 
{ 
     char string[15]; 
     char *ptr, c = 'r';
     strcpy(string, "This is a string"); 
     ptr = strchr(string, c); 
     if (ptr) 
        printf("The character %c is at position: %d\n", c, ptr-string); 
     else 
        printf("The character was not found\n"); 
     return 0; 
} 
  
  
/*
* 函式名: strcmp 
* 功   能: 串比較 
* 用   法: int strcmp(char *str1, char *str2); 
* 看Asic碼,str1>str2,返回值 > 0;兩串相等,返回0
* 程式例:
*/
#include <string.h> 
#include <stdio.h>
int main(void) 
{ 
     char *buf1 = "aaa", *buf2 = "bbb", *buf3 = "ccc"; 
     int ptr;
     ptr = strcmp(buf2, buf1); 
     if (ptr > 0) 
        printf("buffer 2 is greater than buffer 1\n"); 
     else 
        printf("buffer 2 is less than buffer 1\n");
     ptr = strcmp(buf2, buf3); 
     if (ptr > 0) 
        printf("buffer 2 is greater than buffer 3\n"); 
     else 
        printf("buffer 2 is less than buffer 3\n");
     return 0; 
} 
  
/*  
* 函式名: strncmpi 
* 功   能: 將一個串中的一部分與另一個串比較, 不管大小寫 
* 用   法: int strncmpi(char *str1, char *str2, unsigned maxlen); 
* 程式例:
*/
#include <string.h> 
#include <stdio.h>
int main(void) 
{ 
    char *buf1 = "BBB", *buf2 = "bbb"; 
    int ptr;
    ptr = strcmpi(buf2, buf1);
    if (ptr > 0) 
       printf("buffer 2 is greater than buffer 1\n");
    if (ptr < 0) 
       printf("buffer 2 is less than buffer 1\n");
    if (ptr == 0) 
       printf("buffer 2 equals buffer 1\n");
    return 0; 
} 
  
/*  
* 函式名: strcpy 
* 功   能: 串拷貝 
* 用   法: char *strcpy(char *str1, char *str2); 
* 程式例:
*/
#include <stdio.h> 
#include <string.h>
int main(void) 
{ 
     char string[10]; 
     char *str1 = "abcdefghi";
     strcpy(string, str1); 
     printf("%s\n", string); 
     return 0; 
} 
  
/*  
* 函式名: strcspn 
* 功   能: 在串中查詢第一個給定字符集內容的段 
* 用   法: int strcspn(char *str1, char *str2); 
* 程式例:
*/
#include <stdio.h> 
#include <string.h> 
#include <alloc.h>
int main(void) 
{ 
     char *string1 = "1234567890"; 
     char *string2 = "747DC8"; 
     int length;
     length = strcspn(string1, string2); 
     printf("Character where strings intersect is at position %d\n", length);
     return 0; 
} 
  
/*  
* 函式名: strdup 
* 功   能: 將串拷貝到新建的位置處 
* 用   法: char *strdup(char *str); 
* 程式例:
*/
#include <stdio.h> 
#include <string.h> 
#include <alloc.h>
int main(void) 
{ 
     char *dup_str, *string = "abcde";
     dup_str = strdup(string); 
     printf("%s\n", dup_str); 
     free(dup_str);
     return 0; 
} 
  
  
/*
* 函式名: stricmp 
* 功   能: 以大小寫不敏感方式比較兩個串 
* 用   法: int stricmp(char *str1, char *str2); 
* 程式例:
*/
#include <string.h> 
#include <stdio.h>
int main(void) 
{ 
    char *buf1 = "BBB", *buf2 = "bbb"; 
    int ptr;
    ptr = stricmp(buf2, buf1);
    if (ptr > 0) 
       printf("buffer 2 is greater than buffer 1\n");
    if (ptr < 0) 
       printf("buffer 2 is less than buffer 1\n");
    if (ptr == 0) 
       printf("buffer 2 equals buffer 1\n");
    return 0; 
} 
  
/*  
* 函式名: strerror 
* 功   能: 返回指向錯誤資訊字串的指標 
* 用   法: char *strerror(int errnum); 
* 程式例:
*/
#include <stdio.h> 
#include <errno.h>
int main(void) 
{ 
    char *buffer; 
    buffer = strerror(errno); 
    printf("Error: %s\n", buffer); 
    return 0; 
} 
  
/*    
* 函式名: strcmpi 
* 功   能: 將一個串與另一個比較, 不管大小寫 
* 用   法: int strcmpi(char *str1, char *str2); 
* 程式例:
*/
#include <string.h> 
#include <stdio.h>
int main(void) 
{ 
    char *buf1 = "BBB", *buf2 = "bbb"; 
    int ptr;
    ptr = strcmpi(buf2, buf1);
    if (ptr > 0) 
       printf("buffer 2 is greater than buffer 1\n");
    if (ptr < 0) 
       printf("buffer 2 is less than buffer 1\n");
    if (ptr == 0) 
       printf("buffer 2 equals buffer 1\n");
    return 0; 
} 
  
/*    
* 函式名: strncmp 
* 功   能: 串比較 
* 用   法: int strncmp(char *str1, char *str2, int maxlen); 
* 程式例:
*/
#include <string.h> 
#include <stdio.h>
int   main(void)
{ 
    char *buf1 = "aaabbb", *buf2 = "bbbccc", *buf3 = "ccc"; 
    int ptr;
    ptr = strncmp(buf2,buf1,3); 
    if (ptr > 0) 
       printf("buffer 2 is greater than buffer 1\n"); 
    else 
       printf("buffer 2 is less than buffer 1\n");
    ptr = strncmp(buf2,buf3,3); 
    if (ptr > 0) 
       printf("buffer 2 is greater than buffer 3\n"); 
    else 
       printf("buffer 2 is less than buffer 3\n");
    return(0); 
} 
  
/*  
* 函式名: strncmpi 
* 功   能: 把串中的一部分與另一串中的一部分比較, 不管大小寫 
* 用   法: int strncmpi(char *str1, char *str2); 
* 程式例:
*/
#include <string.h> 
#include <stdio.h>
int main(void) 
{ 
    char *buf1 = "BBBccc", *buf2 = "bbbccc"; 
    int ptr;
    ptr = strncmpi(buf2,buf1,3);
    if (ptr > 0) 
       printf("buffer 2 is greater than buffer 1\n");
    if (ptr < 0) 
       printf("buffer 2 is less than buffer 1\n");
    if (ptr == 0) 
       printf("buffer 2 equals buffer 1\n");
    return 0; 
} 
  
/*  
* 函式名: strncpy 
* 功   能: 串拷貝 
* 用   法: char *strncpy(char *destin, char *source, int maxlen); 
* 程式例:
*/
#include <stdio.h> 
#include <string.h>
int main(void) 
{ 
    char string[10]; 
    char *str1 = "abcdefghi";
    strncpy(string, str1, 3); 
    string[3] = '\0'; 
    printf("%s\n", string); 
    return 0; 
} 
  
/*  
* 函式名: strnicmp 
* 功   能: 不注重大小寫地比較兩個串 
* 用   法: int strnicmp(char *str1, char *str2, unsigned maxlen); 
* 程式例:
*/
#include <string.h> 
#include <stdio.h>
int main(void) 
{ 
    char *buf1 = "BBBccc", *buf2 = "bbbccc"; 
    int ptr;
    ptr = strnicmp(buf2, buf1, 3);
    if (ptr > 0) 
       printf("buffer 2 is greater than buffer 1\n");
    if (ptr < 0) 
       printf("buffer 2 is less than buffer 1\n");
    if (ptr == 0) 
       printf("buffer 2 equals buffer 1\n");
    return 0; 
} 
   
/*  
* 函式名: strnset 
* 功   能: 將一個串中的所有字元都設為指定字元 
* 用   法: char *strnset(char *str, char ch, unsigned n); 
* 程式例:
*/
#include <stdio.h> 
#include <string.h>
int main(void) 
{ 
    char *string = "abcdefghijklmnopqrstuvwxyz"; 
    char letter = 'x';
    printf("string before strnset: %s\n", string); 
    strnset(string, letter, 13); 
    printf("string after   strnset: %s\n", string);
    return 0; 
} 
  
/*  
* 函式名: strpbrk 
* 功   能: 在串中查詢給定字符集中的字元 
* 用   法: char *strpbrk(char *str1, char *str2); 
* 程式例:
*/
#include <stdio.h> 
#include <string.h>
int main(void) 
{ 
    char *string1 = "abcdefghijklmnopqrstuvwxyz"; 
    char *string2 = "onm"; 
    char *ptr;
    ptr = strpbrk(string1, string2);
    if (ptr) 
       printf("strpbrk found first character: %c\n", *ptr); 
    else 
       printf("strpbrk didn't find character in set\n");
    return 0; 
} 
  
/*   
* 函式名: strrchr 
* 功   能: 在串中查詢指定字元的最後一個出現 
* 用   法: char *strrchr(char *str, char c); 
* 程式例:
*/
#include <string.h> 
#include <stdio.h>
int main(void) 
{ 
    char string[15]; 
    char *ptr, c = 'r';
    strcpy(string, "This is a string"); 
    ptr = strrchr(string, c); 
    if (ptr) 
       printf("The character %c is at position: %d\n", c, ptr-string); 
    else 
       printf("The character was not found\n"); 
    return 0; 
} 
  
/*  
* 函式名: strrev 
* 功   能: 串倒轉 
* 用   法: char *strrev(char *str); 
* 程式例:
*/
#include <string.h> 
#include <stdio.h>
int main(void) 
{ 
    char *forward = "string";
    printf("Before strrev(): %s\n", forward); 
    strrev(forward); 
    printf("After strrev():   %s\n", forward); 
    return 0; 
} 


/*  
* 函式名: strset 
* 功   能: 將一個串中的所有字元都設為指定字元 
* 用   法: char *strset(char *str, char c); 
* 程式例:
*/
#include <stdio.h> 
#include <string.h>
int main(void) 
{ 
    char string[10] = "123456789"; 
    char symbol = 'c';
    printf("Before strset(): %s\n", string); 
    strset(string, symbol); 
    printf("After strset():   %s\n", string); 
    return 0; 
} 
  
/*  
* 函式名: strspn 
* 功   能: 在串中查詢指定字符集的子集的第一次出現 
* 用   法: int strspn(char *str1, char *str2); 
* 程式例:
*/
#include <stdio.h> 
#include <string.h> 
#include <alloc.h>
int main(void) 
{ 
    char *string1 = "1234567890"; 
    char *string2 = "123DC8"; 
    int length;
    length = strspn(string1, string2); 
    printf("Character where strings differ is at position %d\n", length); 
    return 0; 
} 
  
/*  
* 函式名: strstr 
* 功   能: 在串中查詢指定字串的第一次出現 
* 用   法: char *strstr(char *str1, char *str2); 
* 程式例:
*/
#include <stdio.h> 
#include <string.h>
int main(void) 
{ 
    char *str1 = "Borland International", *str2 = "nation", *ptr;
    ptr = strstr(str1, str2); 
    printf("The substring is: %s\n", ptr); 
    return 0; 
} 
  
/*  
* 函式名: strtod 
* 功   能: 將字串轉換為double型值 
* 用   法: double strtod(char *str, char **endptr); 
* 程式例:
*/
#include <stdio.h> 
#include <stdlib.h>
int main(void) 
{ 
    char input[80], *endptr; 
    double value;
    printf("Enter a floating point number:"); 
    gets(input); 
    value = strtod(input, &endptr); 
    printf("The string is %s the number is %lf\n", input, value); 
    return 0; 
} 
   
/*  
* 函式名: strtok 
* 功   能: 查詢由在第二個串中指定的分界符分隔開的單詞 
* 用   法: char *strtok(char *str1, char *str2); 
* 程式例:
*/
#include <string.h> 
#include <stdio.h>
int main(void) 
{ 
    char input[16] = "abc,d"; 
    char *p;
    /* strtok places a NULL terminator 
    in front of the token, if found */ 
    p = strtok(input, ","); 
    if (p)    printf("%s\n", p);
    /* A second call to strtok using a NULL 
    as the first parameter returns a pointer 
    to the character following the token   */ 
    p = strtok(NULL, ","); 
    if (p)    printf("%s\n", p); 
    return 0; 
} 
  

/*  
* 函式名: strtol 
* 功   能: 將串轉換為長整數 
* 用   法: long strtol(char *str, char **endptr, int base); 
* 程式例:
*/
#include <stdlib.h> 
#include <stdio.h>
int main(void) 
{ 
    char *string = "87654321", *endptr; 
    long lnumber;
    /* strtol converts string to long integer   */ 
    lnumber = strtol(string, &endptr, 10); 
    printf("string = %s   long = %ld\n", string, lnumber);
    return 0; 
} 
  
/*  
* 函式名: strupr 
* 功   能: 將串中的小寫字母轉換為大寫字母 
* 用   法: char *strupr(char *str); 
* 程式例:
*/
#include <stdio.h> 
#include <string.h>
int main(void) 
{ 
    char *string = "abcdefghijklmnopqrstuvwxyz", *ptr;
    /* converts string to upper case characters */ 
    ptr = strupr(string); 
    printf("%s\n", ptr); 
    return 0; 
} 
  
/*  
* 函式名: swab 
* 功   能: 交換位元組 
* 用   法: void swab (char *from, char *to, int nbytes); 
* 程式例:
*/
#include <stdlib.h> 
#include <stdio.h> 
#include <string.h>
char source[15] = "rFna koBlrna d"; 
char target[15];
int main(void) 
{ 
    swab(source, target, strlen(source)); 
    printf("This is target: %s\n", target); 
    return 0; 
}


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