不引入第三个变量交换两个数的值

#include<iostream>#include<string>using namespace std;int main(){    int a,b;    cin>>a>>b;    cout<<"a="<<a<<","<<"b="<<b<<endl;    a=a-b;    b=a+b;    a=b-a;    cout<<"a="<<a<<","<<"b="<<b<<endl;    return 0;}