多态性1

#include<iostream>
using namespace std;
class Complex{
public:
Complex(double r=0.0,double i=0.0):real(r),imag(i) {}
Complex operator+(const Complex &c2) const;
Complex operator-(const Complex &c2) const;
void display() const;
private:
double real;
double imag;
};
Complex Complex::operator+(const Complex &c2) const{
return Complex(real+c2.real,imag+c2.imag);
}
Complex Complex::operator-(const Complex &c2) const{
return Complex(real-c2.real,imag-c2.imag);
}
void Complex::display() const{
cout<<"("<<real<<","<<imag<<")"<<endl;
}
int main()
{
Complex c1(5,4),c2(2,10),c3;
cout<<"c1=";c1.display();
cout<<"c2=";c2.display();
c3=c2-c1;
cout<<"c3=c1-c2=";c3.display();
c3=c1+c2;
cout<<"c3=c2+c1";c3.display();
return 0;
}