運算符重載

運算符重載

函數重載保證用戶能夠定義多個名稱相同但是參數列表不同的函數，希望用戶能夠通過同名的函數完成相同的基本操作。

運算符重載允許C++賦予運算符多種含義，而C++允許將運算符重載擴展到用於自定義的類型。例如允許兩個類對象相加+。

時間Time類

類的聲明

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

#ifndef PROJECT5_TIME_H
#define PROJECT5_TIME_H


class Time {
private:
    int hour;
    int minute;
public:
    Time();//默認構造函數
    Time(int h , int m);//構造函數
    ~Time();//析構函數
    void show() const;
    void reset(int h , int m);
};


#endif //PROJECT5_TIME_H

類的定義

//
// 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;
}

類的使用

#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();
}

測試結果

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

Process finished with exit code 0

算術運算符重載

算術運算符包括一元正號（+）、一元負號（-）、乘法（*）、除法（/），求餘（%），加法（+），減法（-）。

運算符函數的聲明

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

運算符函數的定義

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;
}

運算符函數的使用

#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();
}

測試結果

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

Process finished with exit code 0

項目代碼

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

#ifndef PROJECT5_TIME_H
#define PROJECT5_TIME_H


class Time {
private:
    int hour;
    int minute;
public:
    Time();//默認構造函數
    Time(int h , int m);//構造函數
    ~Time();//析構函數
    void show() const;
    void reset(int h , int m);
    /*重載算術運算符+*/
    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