c++ 用位运算来计算

Question

输入两个数字a和b用位运算输出a-b的值有多组直到输入EOF...

Answer 1

模拟二进制运算。加法运算：将一个整数用二进制表示，其加法运算就是：相异（^）时，本位为1，进位为0；同为1时本位为0，进位为1；同为0时，本位进位均为0。所以，不计进位的和为sum = a^b，进位就是arr = a&b,(与sum相加时先左移一位，因为这是进位）。完成加法直到进位为0.int add(int a, int b) //递归形式{&nbsp; &nbsp; if(b==0) //递归结束条件：如果右加数为0，即不再有进位了，则结束。&nbsp; &nbsp; &nbsp; &nbsp; return a;&nbsp; &nbsp; int s = a^b;&nbsp; &nbsp; int c = (a&b)<<1; //进位左移1位，达到进位的目的。&nbsp; &nbsp; return add(s, c); //再把'和'和'进位'相加。递归实现。}int add(int a, int b) //非递归形式{&nbsp; &nbsp; int s, c;&nbsp; &nbsp; while(b != 0)&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; s = a^b;&nbsp; &nbsp; &nbsp; &nbsp; c = (a&b)<<1;&nbsp; &nbsp; &nbsp; &nbsp; a = s;&nbsp; &nbsp; &nbsp; &nbsp; b = c;&nbsp; &nbsp; }&nbsp; &nbsp; return a;