C語言區域性變數、全域性變數、靜態區域性變數、靜態全域性變數

建立三個檔案，檔名分別為main.c \ head1.c \  head2.c

main.c

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


int A;

void show(){
    volatile static int a ;//靜態區域性變數(static) 靜態區域性變數定義時前面加static關鍵字。
    a++;
    f1(a);
    f2(a);
    //printf("show: B = %d\n",B);
}

void main(int *argv, char *args[]){

    show();
    show();
    show();
    show();
    int c;
    static int b = 10;
}

head1.c

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
static int B ;
int A;
void f1(int a){

    A++,B++;
    printf("head1.h:f1(%d), A = %d, B = %d\n",a,A,B);

}

head2.c

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
static int B;
int A;
void f2(int a){

    A += 2, B += 2;
    printf("head2.h:f2(%d), A = %d, B = %d\n",a,A,B);

}

編譯與執行結果：

-bash-4.1$ gcc -o a Demo.c head*.c
-bash-4.1$ ./a
head1.h:f1(1), A = 1, B = 1
head2.h:f2(1), A = 3, B = 2
head1.h:f1(2), A = 4, B = 2
head2.h:f2(2), A = 6, B = 4
head1.h:f1(3), A = 7, B = 3
head2.h:f2(3), A = 9, B = 6
head1.h:f1(4), A = 10, B = 4
head2.h:f2(4), A = 12, B = 8
-bash-4.1$