(10)C++ 使用类

#include<iostream>
using namespace std;

class Sum {
    int add;
public:
    Sum(int add) {
        this->add = add;
    }
    int operator+(const Sum & sum) const {
        int res;
        res = this->add + sum.add;
        return res;
    }
    int show() {
        return add;
    }
};
int main() {
    Sum sum1(10);
    Sum sum2(20);
    int c=sum1.operator+(sum2);
    cout << c << endl;
    int d = sum1 + sum2; //等同于
    cout << d << endl;
}