重载运算符“+”，使之能用于两个复数相加

#include<iostream>
using namespace std;
class Complex
{
public:
Complex(){real=0;imag=0;}
Complex(double r,double i){real=r;imag=i;}
Complex operator+(Complex& c2);//声明重载运算符+的函数operator
void display();
private:
double real;
double imag;
};

Complex Complex::operator+(Complex& c2)
{
Complex c;
c.real=real+c2.real;
c.imag=imag+c2.imag;
return c;
}

void Complex::display()
{cout<<"("<<real<<","<<imag<<")"<<endl;}

int main()
{
Complex c1(3,4),c2(5,-10),c3;
c3=c1+c2;
cout<<"c1=";c1.display();
cout<<"c2=";c2.display();
cout<<"c3=";c3.display();
return 0;
}