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