第七章  运算符重载

一、填空题

1、在下列程序的空格处填上适当的字句，使输出为：0，2，10。

#include <iostream>

#include <math.h>

class Magic

{double x;

public:

Magic(double d=0.00):x(fabs(d))

{}

Magic operator+(_const Magic &c_____)

{

return Magic(sqrt(x*x+c.x*c.x));

}

_ostream operator<<(ostream & stream,const  Magic & c)

{ stream<<c.x;

return stream;

}

};

int main()

{Magic ma;

cout<<ma<<", "<<Magic(2)<<", "<<ma+Magic(-6)+

Magic(-8)<<endl;

}

二、编程题

1、 定义复数类的加法与减法，使之能够执行下列运算：

  Complex a(2，5)，b(7，8)，c(0，0);

  c=a+b;

  c=4.1+a;

  c=b+5.6;

#include <iostream>using namespace std;class Complex
{friend class Constant;
private:double x;double y;
public:Complex(double x=0,double y=0):x(x),y(y){}const Complex operator+(const Complex &c) const{Complex temp;temp.x=x+c.x;temp.y=y+c.y;return temp;}const Complex operator+(const double x) const{Complex temp;temp.x=this->x+x;temp.y=y;return temp;}void show(){cout << x << "   " << y << endl;}
};class Constant
{
private:double x;
public:Constant(double x=0):x(x){}const Complex operator+(const Complex &c) const{Complex temp;temp.x=x+c.x;temp.y=x+c.y;return temp;}
};int main()
{Complex a(2,5);Complex b(7,8);Complex c;Constant d(4.1);c=a+b;c.show();c=d+a;c.show();c=b+5.6;c.show();return 0;
}

2、 编写一个时间类，实现时间的加、减、读和输出。

#include <iostream>using namespace std;class Time
{
private:int hour;int min;int sec;
public:Time(int hour=0,int min=0,int sec=0):hour(hour),min(min),sec(sec){}const Time operator+(const Time &t) const{Time temp;int flag=0;temp.sec=sec+t.sec;if(temp.sec>=60){flag=1;temp.sec-=60;}temp.min=min+t.min;if(flag==1){temp.min++;}if(temp.min>=60){flag=2;temp.min-=60;}temp.hour=hour+t.hour;if(flag==2){temp.hour++;}if(temp.hour>=24){temp.hour-=24;}return temp;}const Time operator-(const Time &t) const{Time temp;int flag=0;temp.sec=sec-t.sec;if(temp.sec<0){flag=1;temp.sec+=60;}temp.min=min-t.min;if(flag==1){temp.min--;}if(temp.min<0){flag=2;temp.min+=60;}temp.hour=hour-t.hour;if(flag==2){temp.hour--;}if(temp.hour<0){temp.hour+=24;}return temp;}void show(){cout << hour << " : " << min << " : " << sec << endl;}
};int main()
{Time t1(22,51,33);Time t2(15,44,55);Time t3=t1+t2;t3.show();Time t4=t2-t1;t4.show();return 0;
}

3、 增加操作符，以允许人民币与double型数相乘。

  friend money operator*(const money&，double);

  friend money operator*(double，const money&);

  注意：两个money对象不允许相乘。

#include <iostream>using namespace std;class Money {private:double amount;public:Money(double amt = 0.0) : amount(amt) {}friend Money operator*(const Money& money, double num) {return Money(money.amount * num);}friend Money operator*(double num, const Money& money) {return Money(money.amount * num);}
};