判断big endian和little endian的方法

Big endian machine: It thinks the first byte it reads is the biggest.

Little endian machine: It thinks the first byte it reads is the littlest.

#include <stdio.h>

int main(int argc, char **argv)
{
        union {
          short  s;
      char   c[sizeof(short)];
    } un;

        un.s = 0x0102;
        if (sizeof(short) == 2) {
                if (un.c[0] == 1 && un.c[1] == 2)
                        printf("big-endian\n");
                else if (un.c[0] == 2 && un.c[1] == 1)
                        printf("little-endian\n");
                else
                        printf("unknown\n");
        } else
                printf("sizeof(short) = %d\n", sizeof(short));

        exit(0);
}

总结一下：big endian是适合大家的阅读顺序，little endian则相反。