确定主机字节序

#include <stdio.h>intmain(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));    return 0;}