字节排序函数

#include <stdio.h>

int main(int argc, char *argv[])
{
union

{
unsigned short num;
unsigned char arr[sizeof(short)];
}test;

test.num = 0x0102;

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

exit(0);
}