实验目的和要求
实验内容
1.调试下列程序
- "font-family:SimSun;font-size:16px;">//sy7_1.cpp
- #include<iostream>
- usingnamespace
- class
- public
- double
- doubledouble
- const
- const
- const
- const
- friendvoidconst
- private
- double
- inlineconst
- return
- inlineconst
- return
- inlineconst
- return
- inlineconst
- return
- voidconst
- if
- "i"
- else
- "+"<<c.imag<<"i"
- int
- return
//sy7_1.cpp #include<iostream> using namespace std; class complex { public: complex(){real=imag=0.0;} complex(double r){real=r;imag=0.0;} complex(double r,double i){real=r;imag=i;} complex operator + (const complex &c); complex operator - (const complex &c); complex operator * (const complex &c); complex operator / (const complex &c); friend void print(const complex &c); private: double real,imag; }; inline complex complex::operator + (const complex &c) { return complex(real+c.real,imag+c.imag); } inline complex complex::operator - (const complex &c) { return complex(real-c.real,imag-c.imag); } inline complex complex::operator * (const complex &c) { return complex(real*c.real-imag*c.imag,real*c.imag+imag*c.real); } inline complex complex::operator / (const complex &c) { return complex((real*c.real+imag*c.imag)/(c.real*c.real+c.imag*c.imag),(imag*c.real-real*c.imag)/(c.real*c.real+c.imag*c.imag)); } void print(const complex &c) { if(c.imag<0) cout<<c.real<<c.imag<<"i"; else cout<<c.real<<"+"<<c.imag<<"i"; } int main() { complex c1(2.0),c2(3.0,-1.0),c3; c3=c1+c2; cout<<"\nc1+c2= "; print(c3); c3=c1-c2; cout<<"\nc1-c2= "; print(c3); c3=c1*c2; cout<<"\nc1*c2= "; print(c3); c3=c1/c2; cout<<"\nc1/c2= "; print(c3); c3=(c1+c2)*(c1-c2)*c2/c1; cout<<"\n(c1+c2)*(c1-c2)*c2/c1= "; print(c3); cout<<endl; return 0; }写出程序的输出结果，并解释
2.调试下列程序
- "font-family:SimSun;""font-size:16px;">//sy7_1.cpp
- #include<iostream>
- usingnamespace
- class
- public
- double
- doubledouble
- friendconstconst
- friendconstconst
- friendconstconst
- friendconstconst
- friendvoidconst
- private
- double
- constconst
- return
- constconst
- return
- constconst
- return
- constconst
- return
- voidconst
- if
- "i"
- else
- "+"<<c.imag<<"i"
- int
- return
//sy7_1.cpp #include<iostream> using namespace std; class complex { public: complex(){real=imag=0.0;} complex(double r){real=r;imag=0.0;} complex(double r,double i){real=r;imag=i;} friend complex operator + (const complex &c1,const complex &c2); friend complex operator - (const complex &c1,const complex &c2); friend complex operator * (const complex &c1,const complex &c2); friend complex operator / (const complex &c1,const complex &c2); friend void print(const complex &c); private: double real,imag; }; complex operator + (const complex &c1,const complex &c2) { return complex(c1.real+c2.real,c1.imag+c2.imag); } complex operator - (const complex &c1,const complex &c2) { return complex(c1.real-c2.real,c1.imag-c2.imag); } complex operator * (const complex &c1,const complex &c2) { return complex(c1.real*c2.real-c1.imag*c2.imag,c1.real*c2.imag+c1.imag*c2.real); } complex operator / (const complex &c1,const complex &c2) { return complex((c1.real*c2.real+c1.imag*c2.imag)/(c2.real*c2.real+c2.imag*c2.imag),(c1.imag*c2.real-c1.real*c2.imag)/(c2.real*c2.real+c2.imag*c2.imag)); } void print(const complex &c) { if(c.imag<0) cout<<c.real<<c.imag<<"i"; else cout<<c.real<<"+"<<c.imag<<"i"; } int main() { complex c1(2.0),c2(3.0,-1.0),c3; c3=c1+c2; cout<<"\nc1+c2= "; print(c3); c3=c1-c2; cout<<"\nc1-c2= "; print(c3); c3=c1*c2; cout<<"\nc1*c2= "; print(c3); c3=c1/c2; cout<<"\nc1/c2= "; print(c3); c3=(c1+c2)*(c1-c2)*c2/c1; cout<<"\n(c1+c2)*(c1-c2)*c2/c1= "; print(c3); cout<<endl; return 0; }写出程序的输出结果，并解释
3.定义一个Time类用来保存时间（时，分，秒），通过重载操作符“+”实现两个时间的相加。（sy7_3.cpp）
编写程序如下：
- "font-family:SimSun;font-size:16px;"//sy7_3.cpp
- class
- public
- //无参构造函数
- intintint//重载构造函数
- //操作符重载为成员函数，返回结果为Time类
- void
- private
- int
- int
- return
- void
- "%d:%d:%d\n"
- int
- return
//sy7_3.cpp #include <stdio.h> class Time { public: Time(){ hours=0;minutes=0;seconds=0;} //无参构造函数 Time(int h, int m,int s) //重载构造函数 { hours=h; minutes=m; seconds=s; } Time operator +(Time&); //操作符重载为成员函数，返回结果为Time类 void gettime(); private: int hours,minutes,seconds; }; Time Time::operator +(Time& time) { int h,m,s; s=time.seconds+seconds; m=time.minutes+minutes+s/60; h=time.hours+hours+m/60; Time result(h,m%60,s%60); return result; } void Time::gettime() { printf("%d:%d:%d\n",hours,minutes,seconds); } int main( ) { Time t1(20,30,40),t2(3,15,20),t3; t3=t1+t2; t3.gettime(); return 0; }程序输出结果如下：
分析与讨论
答：运算符函数重载一般有两种形式：重载为类的成员函数和重载为类的非成员函数。非成员函数通常是友元。（可以把一个运算符作为一个非成员、非友元函数重载；但是，这样的运算符函数访问类的私有和保护成员时，必须使用类的公有接口中提供的设置数据和读取数据的函数，调用这些函数时会降低性能。可以内联这些函数以提高性能。）
this指针隐式地访问了类的一个对象，它充当了运算符函数最左边的操作数。因此：双目运算符重载为类的成员函数时，函数只显式说明一个参数，该形参是运算符的右操作数。前置单目运算符重载为类的成员函数时，不需要显式说明参数，即函数没有形参。后置单目运算符重载为类的成员函数时，函数要带有一个整型形参。
this指针，因此操作数的个数没有变化，所有的操作数都必须通过函数的形参进行传递，函数的参数与操作数自左至右一一对应。
实验总结
运算符重载的定义，运算符重载就是对已有的运算符重新进行定义，赋予其另一种功能，以适应不同的数据类型。重载运算符必须遵循的规则有：重载运算符必须符合语言语法、不能重载内部C++数据类型进行操作的运算符、不能创建新的运算符、不能重载. .* :: ?:这些运算符、重载运算符要保持原有的基本语义不变。若用成员函数重载运算符需要的参数的个数总比它的操作数少一个，若用友元函数重载运算符需要的参数的个数总比它的操作数一样多。同时也多运算符重载的使用方法有了一定的了解。
文章来源: 实验7 运算符重载（P289-P292）