省流

前置递增(递减)返回引用，后置递增(递减)返回值

代码

#include <iostream>
using namespace std;

class myInt {
	friend ostream& operator<< (ostream &cout,myInt myint);
public:
	myInt() {
		m_Num = 0;
	}
	//前置递增
	myInt& operator++() {
		m_Num++;//先进行++运算
		return *this;//再将自身返回
	}
	//后置递增
	myInt operator++(int) {
		myInt temp = *this;//先记录结果
		m_Num++;//再递增
		return temp;//返回记录结果
	}

	//前置递减
	myInt &operator--() {
		m_Num--;
		return *this;
	}
	//后置递减
	myInt operator--(int) {
		myInt temp = *this;//先记录
		m_Num--;//再递减
		return temp;//最后返回
	}

private:
	int m_Num;
};

ostream &operator<< (ostream &cout,myInt myint) {
	cout << myint.m_Num;
	return cout;
}

void test1() {
	myInt myint;
	cout << "递增" << endl;
	cout << ++myint << endl;
	cout << myint++ << endl;
	cout << myint << endl;
}
void test2() {
	myInt myint;
	cout << "递减" << endl;
	cout << --myint << endl;
	cout << myint-- << endl;
	cout << myint << endl;
}

int main(){
	test1();//递增
	test2();//递减
	return 0;
}