1、成员函数版本实现算术运算符的重载；全局函数版本实现算术运算符的重载

#include <iostream>

using namespace std;

class Test
{
    friend const Test operator-(const Test &L,const Test &R);
private:
    int c;
    int n;
public:
    Test(){}
    Test(int c,int n):c(c),n(n)
    {}
    //类内成员函数实现+运算符重载
    const Test operator+(const Test &T)const
    {
        Test temp;
        temp.c = c+T.c;
        temp.n = n+T.n;
        return temp;
    }

    void show()
    {
        cout << "c = " << c << "n = " << n << endl;

    }
};
//全局函数实现—运算符重载
const Test operator-(const Test &L,const Test &R)
{
    Test temp;
    temp.c = L.c-R.c;
    temp.n = L.n-R.n;
    return temp;
}

int main()
{
    Test t1('K',4);
    Test t2('Y',8);
    Test t3 = t1 + t2;
    t3.show();
    Test t4 = t1 - t2;
    t4.show();
    return 0;
}

2、思维导图