递增运算符

#include<iostream>
using namespace std;
class person
{
    friend ostream& operator<<(ostream& cout, person p);//声明友元全局函数，使得该函数可以访问私有成员属性age
public:
    person& operator++()//前置递增++p，这里person后面跟随一个&，是因为要执行++(++p)操作必须得是同一个对象
    {
        age++;
        return *this;
    }
    person operator++(int)//后置递增p++
    {
        person temp = *this;
        age++;
        return temp;
    }
private:
    int age=0;
};
ostream& operator<<(ostream& cout, person p)
{
    cout << p.age;
    return cout;
}
void test()
{
    person p;
    cout << p++;
    cout << ++p;
}
int main()
{
    test();
}