C++运算符重载范例

#include<iostream>
using namespace std;

int add(int a, int b)
{
    return a+b;
}

int main()
{
    string s1 ="abc";
    string s2 ="def";
    string s3 = s1 + s2;

    cout<<s3<<endl;
    cout<<add(10,9)<<endl;
    cout<<10+9<<endl;
    return 0;
}