简单传址函数

#include<iostream>
using namespace std;
int sum(int &, int &);
int main()
{
    int main_a,main_b;
    cout<<"请输入两个数字：";
    cin>>main_a>>main_b;
    cout<<"调用前："<<endl;
    cout<<"main_a="<<main_a<<"\t"<<"main_b="<<main_b<<endl;
    cout<<main_a<<"+"<<main_b<<"="<<sum(main_a,main_b)<<endl;
    cout<<"调用后："<<endl;
    cout<<"main_a="<<main_a<<"\t"<<"main_b"<<main_b<<endl;
    return 0; 
}
int sum(int & a,int & b)
{
    int sum=a+b;
    int temp;
    temp=a;
    a=b;
    b=temp;
    cout<<"函数内\na="<<a<<"\t"<<"b="<<b<<endl;
    return sum; 
}