c++运算符重载

complex.h

#ifndef _COMPLEX_H_
#define _COMPLEX_H_
#include <iostream>
using namespace std;
class Complex{
friend ostream& operator<<(ostream& out,const Complex& c);
friend istream& operator>>(istream& input,Complex& c);
friend Complex operator*(const Complex c1,const Complex c2);
friend Complex operator/(const Complex c1,const Complex c2);
friend Complex& operator++(Complex&c);//前缀
friend Complex operator++(Complex&c,int);//后缀
public:
Complex(int x=1,int y=1):a(x),b(y){};
Complex operator+(const Complex c);
Complex operator-(const Complex c);
Complex& operator--();//前缀
Complex operator--(int);//后缀
operator int();//只能是成员函数 不必写返回值类型 无形参 强制类型转换
protected:
private:
int a;
int b;
};
#endif
/*不能重载的运算符只有5个：类属关系运算符“.”，成员指针运算符“*”，作用域分辨符“::”，sizeof运算符和三目运算符“?:”*/
Complex.cpp

#include "Complex.h"

ostream& operator<<(ostream& out,const Complex& c){
if (c.a==0){
if (c.b==0)
out<<"0";
else
out<<c.b<<"i";
}else if (c.b<0){
out<<c.a<<c.b<<"i";
}else if(c.b==0){
out<<c.a;
}else{
out<<c.a<<"+"<<c.b<<"i";
}
return out;
}

istream& operator>>(istream& input,Complex& c){
cout<<"please input the a and b:";
input>>c.a>>c.b;
return input;
}

Complex Complex::operator +(const Complex c){
return Complex(a+c.a,b+c.b);
}

Complex Complex::operator -(const Complex c){
return Complex(a-c.a,b-c.b);
}

Complex operator*(const Complex c1,const Complex c2){
int aa = c1.a*c2.a-c1.b*c2.b;
int bb = c1.a*c2.b+c1.b*c2.a;
return Complex(aa,bb);
}

Complex operator/(const Complex c1,const Complex c2){
int aa = (c1.a*c2.a+c1.b*c2.b)/(c2.a*c2.a+c2.b*c2.b);
int bb = (c1.b*c2.a+c1.a*c2.b)/(c2.a*c2.a+c2.b*c2.b);
return Complex(aa,bb);
}

Complex& operator++(Complex&c){//前缀
c.a +=10;
return c;
}

Complex& Complex::operator --(){//前缀
a -= 10;
return *this;
}

Complex operator++(Complex&c,int){//后缀
Complex old(c);
c.a +=1;
return old;
}

Complex Complex::operator --(int){//后缀
Complex old(*this);
a -= 1;
return old;
}

Complex::operator int(){
return a;
}main.cpp

#include "complex.h"
#include <iostream>

using namespace std;

int main(){
cout<<"hello world!"<<endl;
Complex c(1,2);
cout<<"c="<<c<<endl;
Complex cc;
cin>>cc;
cout<<"cc="<<cc<<endl;
cout<<"cc+c="<<cc+c<<endl;
cout<<"cc-c="<<cc-c<<endl;
cout<<"cc*c="<<cc*c<<endl;
cout<<"cc/c="<<cc/c<<endl;
cout<<"++cc="<<++cc<<endl;
cout<<"--c="<<--c<<endl;
cout<<"cc++="<<cc++<<endl;
cout<<"cc="<<cc<<endl;
cout<<"c--="<<c--<<endl;
cout<<"c="<<c<<endl;
cout<<"int(c)="<<int(c)<<endl;
return 0;
}