【C++总结】运算符重载

Timer t1;
Timer t2;
t1 + t2;//t1和t2是对象，不能相加

成员函数形式重载运算符

const Timer operator+(Timer t);//重载+号运算符，调用的时候默认有个this形参

const Timer Timer::operator+(Timer t) {//千万不能返回引用
Timer time;
time.hour = this->hour + t.hour;
time.minute = this->minute + t.minute;
return time;
}

使用友元函数形式重载运算符

friend const Timer operator-(Timer t1, Timer t2);//使用友元形式重载

const Timer operator-(Timer t1, Timer t2) {//两个参数显示给出
Timer time;
time.hour = t1.hour - t2.hour;
time.minute = t1.minute - t2.minute;
return time;
}

重载<<输出操作符

friend const ostream& operator<<(ostream &os, Timer t);//可以直接输出对象

const ostream& operator<<(ostream &os, Timer t) {//和java中toString一样
os << "时间是：" << t.hour << ":" << t.minute << endl;
return os;
}

综合例子

#include <iostream>
using namespace std;

class Timer {
public:
int hour;
int minute;
public:
Timer(){}

Timer(int hour, int minute):hour(hour), minute(minute) {}

const Timer operator+(Timer t);//重载+号运算符

friend const Timer operator-(Timer t1, Timer t2);//重载-号运算符

friend const ostream& operator<<(ostream &os, Timer t);//重载<<
};

const Timer Timer::operator+(Timer t) {
Timer time;
time.hour = this->hour + t.hour;
time.minute = this->minute + t.minute;
return time;
}

const Timer operator-(Timer t1, Timer t2) {
Timer time;
time.hour = t1.hour - t2.hour;
time.minute = t1.minute - t2.minute;
return time;
}

const ostream& operator<<(ostream &os, Timer t) {
os << "时间是：" << t.hour << ":" << t.minute << endl;
return os;
}

int main() {
Timer t1 = {2, 15};
Timer t2 = {3, 15};

Timer t3 = t1 + t2;
cout << t3.hour << "-------" << t3.minute << endl;
cout << t3;

Timer t4 = t2 - t1;
cout << t4.hour << "-------" << t4.minute << endl;
cout << t4;
return 0;
}