不使用中间变量交换整型数据的值

思想就是通过简单的加减运算凑出最终的值。

代码：

#include <iostream>
using namespace std;
int main()
{
     int a = 1;
     int b = 4;
     
     cout << "before swap" << endl;
     cout <<"a= " << a<< endl;
     cout <<"b= " << b<< endl;
     
     //do swap without temp
     a = a - b;
     b = a + b;
     a = b - a;
     
     cout << "after swap" << endl;
     cout <<"a= " << a<< endl;
     cout <<"b= " << b<< endl;
     return 0;
}