C语言判断大小端

 1 #include <stdio.h>
 2 typedef unsigned char BYTE;
 3 int main(int argc, char* argv[])
 4 {
 5     unsigned int num,*p;
 6     p = &num;
 7     num = 0;
 8     *(BYTE *)p = 0xff;
 9     if(num == 0xff)
10     {
11         printf("little\n");
12     }
13     else //num == 0xff000000
14     {
15         printf("big\n");
16     }
17     return 0;
18 }

 1 int checkCPU()
 2 { 4    union w
 5    {
 6       int a;
 7       char b;
 8    }c;
 9    c.a = 1;
10    return (c.b == 1);12 }