运算符重载

运算符重载

函数重载保证用户能够定义多个名称相同但是参数列表不同的函数，希望用户能够通过同名的函数完成相同的基本操作。

运算符重载允许C++赋予运算符多种含义，而C++允许将运算符重载扩展到用于自定义的类型。例如允许两个类对象相加+。

时间Time类

类的声明

//
// Created by Rdw on 2017/3/9.
//

#ifndef PROJECT5_TIME_H
#define PROJECT5_TIME_H


class Time {
private:
    int hour;
    int minute;
public:
    Time();//默认构造函数
    Time(int h , int m);//构造函数
    ~Time();//析构函数
    void show() const;
    void reset(int h , int m);
};


#endif //PROJECT5_TIME_H

类的定义

//
// Created by Rdw on 2017/3/9.
//

#include "Time.h"
#include <iostream>

using namespace std;

Time::Time() {

}

Time::Time(int h, int m) {
    hour = h;
    minute = m;
}

Time::~Time() {

}

void Time::reset(int h, int m) {
    hour = h;
    minute = m;
}

void Time::show() const {
    cout << hour << "hours " << minute << "minutes" << endl;
}

类的使用

#include <iostream>
#include "Time.h"

using namespace std;

int main() {
    Time time1 = Time(14 , 46);
    time1.show();

    Time time2(8 , 30);
    time2.show();

    time1.reset(7 , 0);
    time1.show();
}

测试结果

E:\Project5\cmake-build-debug\Project5.exe
14hours 46minutes
8hours 30minutes
7hours 0minutes

Process finished with exit code 0

算术运算符重载

算术运算符包括一元正号（+）、一元负号（-）、乘法（*）、除法（/），求余（%），加法（+），减法（-）。

运算符函数的声明

friend Time operator+(const Time &object1 , const Time &object2);

运算符函数的定义

Time operator+(const Time &object1, const Time &object2) {
    Time sum;
    int temp;
    temp = (object1.hour * 60 + object1.minute) + (object2.hour * 60 + object2.minute);
    sum.hour = temp / 60;
    sum.minute = temp % 60;
    return sum;
}

运算符函数的使用

#include <iostream>
#include "Time.h"

using namespace std;

int main() {
    Time time1 = Time(14 , 46);
    time1.show();

    Time time2(8 , 30);
    time2.show();

    time1.reset(7 , 0);
    time1.show();

    Time time3;
    time3 = time1 + time2;
    time3.show();
}

测试结果

E:\Project5\cmake-build-debug\Project5.exe
14hours 46minutes
8hours 30minutes
7hours 0minutes
15hours 30minutes

Process finished with exit code 0

项目代码

//
// Created by Rdw on 2017/3/9.
//

#ifndef PROJECT5_TIME_H
#define PROJECT5_TIME_H


class Time {
private:
    int hour;
    int minute;
public:
    Time();//默认构造函数
    Time(int h , int m);//构造函数
    ~Time();//析构函数
    void show() const;
    void reset(int h , int m);
    /*重载算术运算符+*/
    friend Time operator+(const Time &object1 , const Time &object2);
    friend Time operator-(const Time &object1 , const Time &object2);
    friend Time operator*(const Time &object1 , const Time &object2);
    friend Time operator/(const Time &object1 , const Time &object2);
};


#endif //PROJECT5_TIME_H

//
// Created by Rdw on 2017/3/9.
//

#include "Time.h"
#include <iostream>

using namespace std;

Time::Time() {

}

Time::Time(int h, int m) {
    hour = h;
    minute = m;
}

Time::~Time() {

}

void Time::reset(int h, int m) {
    hour = h;
    minute = m;
}

void Time::show() const {
    cout << hour << "hours " << minute << "minutes" << endl;
}

Time operator+(const Time &object1, const Time &object2) {
    Time sum;
    int temp;
    temp = (object1.hour * 60 + object1.minute) + (object2.hour * 60 + object2.minute);
    sum.hour = temp / 60;
    sum.minute = temp % 60;
    return sum;
}

Time operator-(const Time &object1, const Time &object2) {
    Time sub;
    int temp;
    temp = (object1.hour * 60 + object1.minute) - (object2.hour * 60 + object2.minute);
    sub.hour = temp / 60;
    sub.minute = temp % 60;
    return sub;
}

Time operator*(const Time &object1, const Time &object2) {
    Time mult;
    int temp;
    temp = (object1.hour * 60 + object1.minute) * (object2.hour * 60 + object2.minute);
    mult.hour = temp / 60;
    mult.minute = temp % 60;
    return mult;
}

Time operator/(const Time &object1, const Time &object2) {
    Time div;
    int temp;
    temp = (object1.hour * 60 + object1.minute) / (object2.hour * 60 + object2.minute);
    div.hour = temp / 60;
    div.minute = temp % 60;
    return div;
}

#include <iostream>
#include "Time.h"

using namespace std;

int main() {
    Time time1 = Time(14 , 46);
    time1.show();

    Time time2(8 , 30);
    time2.show();

    time1.reset(7 , 0);
    time1.show();

    Time time3;
    time3 = time1 + time2;
    time3.show();

    Time time4 = time3 - time2;
    time4.show();

    Time time5 = time1 * time2;
    time5.show();

    Time time6 = time5 / time1;
    time6.show();
}

E:\Project5\cmake-build-debug\Project5.exe
14hours 46minutes
8hours 30minutes
7hours 0minutes
15hours 30minutes
7hours 0minutes
3570hours 0minutes
8hours 30minutes

Process finished with exit code 0