union数据结构的巧用-判断机器字节序

#include 
void byteorder()
{
    union
    {
        short value;
        char union_bytes[sizeof(short)];
    } test;
    test.value = 0x0102;
    if((test.union_bytes[0] == 1)&&(test.union_bytes[1] == 2))
    {
        printf("big endian\n");
    }
    else if((test.union_bytes[0] == 2)&&(test.union_bytes[1] == 1))
    {
        printf("little endian\n");
    }
    else
        printf("unknown...\n");
}
int main()
{
    byteorder();
    return 0;
}