题目：将一个4字节整数的二进制表示中的001替换为011

答：

int replace(int num){    unsigned int mode3bit = 7;    unsigned int mode1bit = 1;    int shift = 0;    int result = 0;    while (shift < 32)    {        while (shift < 32 && (num & (mode3bit<
     
      = 32)        {            break;        }        else if (32 - shift < 3)  //高位不足3位        {            result += (num & (mode3bit<