#include <stdio.h>
#include <stdlib.h>
int main()
{
//通过位运算实现数字的反转(操作的对象必须是整数)
unsigned int original =0x123;
unsigned int result =0;
unsigned int mask =0xF; //掩码
result |=original&mask;
original>>=4;
result<<=4;
result |=original&mask;
original>>=4;
result<<=4;
result|=original & mask;
printf("%X\n",result);
return 0;
}原文:http://blog.csdn.net/u010296979/article/details/41014659