//例8-1复数类加减法运算重载为成员函数
#include<iostream>
using namespace std;
class Complex{
public:Complex(double r = 0.0, double i = 0.0):real(r), image(i){}Complex operator +(const Complex &c2) const;Complex operator -(const Complex &c2) const;void display() const;
private:double real;double image;
};
Complex Complex::operator+(const Complex &c2) const{return Complex(real+c2.real, image+c2.image);//创建一个临时无名对象作为返回值
}
Complex Complex::operator-(const Complex &c2) const{return Complex(real-c2.real, image-c2.image);
}
void Complex::display() const{cout << "(" << real << ", " << image << ")" << endl;
}
int main(){Complex c1(5,4),c2(2,10),c3;cout << "c1 = "; c1.display();cout << "c2 = "; c2.display();c3 = c1 - c2;cout << "c3 = c1 - c2 = "; c3.display();c3 = c1 + c2;cout << "c3 = c1 + c2 = "; c3.display();return 0;
}

//例8-2重载前置++和后置++为时钟类成员函数
#include<iostream>
using namespace std;
class Clock{
public:Clock(int hour = 0, int minute = 0, int second = 0);void showTime() const;Clock& operator ++();//前置单目运算符重载Clock operator ++ (int);//用参数表来区分两个重载函数，函数体中不适用
private:int hour, minute, second;
};
Clock::Clock(int hour, int minute, int second){if(0 <= hour && hour < 24 && 0 <= minute && minute < 60 && 0 <= second && second <60){this->hour = hour;this->minute = minute;this->second = second;}else{cout << "Time error!" << endl;}
}
void Clock::showTime() const{cout << hour << " : " << minute << " : " << second << endl;
}
Clock &Clock::operator ++ (){//返回本类对象的引用second++;if(second >= 60){second-=60;minute++;if(minute >= 60){minute-=60;hour = (hour+1)%24;}}return *this;
}
Clock Clock::operator ++(int){Clock old = *this;++(*this);//调用前置++运算符（形参）return old;
}
int main(){Clock myClock(23,59,59);cout << "First time output: ";myClock.showTime();cout << "Show myClock++: ";(myClock++).showTime();cout << "Show ++myClock: ";(++myClock).showTime();return 0;
}

//例8-3 重载Complex的加减法和“<<”运算符为非成员函数
#include<iostream>
using namespace std;
class Complex{
public:Complex(double r = 0.0, double i = 0.0):real(r), image(i){}friend Complex operator+(const Complex &c1, const Complex &c2);friend Complex operator-(const Complex &c1, const Complex &c2);//它的左操作数是std::ostream引用，右操作数为复数类的常引用，返回std::ostream引用friend ostream &operator<<(ostream &out, const Complex &c);
private:double real;double image;
};Complex operator+(const Complex &c1, const Complex &c2){return Complex(c1.real+c2.real, c1.image+c2.image);
}
Complex operator-(const Complex &c1, const Complex &c2){return Complex(c1.real-c2.real, c1.image-c2.image);
}
ostream &operator<<(ostream &out, const Complex &c){out << "(" << c.real << ", " << c.image << ")";return out;
}
int main(){Complex c1(5,4),c2(2,10),c3;cout << "c1 = " << c1 << endl;cout << "c2 = " << c2 << endl;c3 = c1 - c2;cout << "c3 = c1 - c2 = " << c3 << endl;c3 = c1 + c2;cout << "c3 = c1 + c2 = " << c3 << endl;return 0;
}