【C++总结】运算符重载

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常规的运算符只能计算基本类型的变相，没办法将对象相加或者相减

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

要想能实现对象的运算，必须要重载运算符

成员函数形式重载运算符

重载运算符只需要把函数名换成operator+

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

使用友元函数形式的重载，参数形式要显示给出，成员函数是一个，这边就该是两个

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

使用友元形式。这样就可以直接输出对象。cout << t1;

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;}

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