哪位大神能帮忙看看下边的空格里该填写什么。。

Question

#include <iostream.h>
class Complex
{
public:
 Complex(){real=0;imag=0;}
 Complex(double r){real=r;imag=0;}
 Complex(double r,double i){real=r;imag=i;}
 friend Complex operator+ (Complex &c1,Complex &c2);
 _____________
private:
 _____________
 double imag;
};

Complex operator+ (Complex &c1,Complex &c2)
{return Complex(c1.real+c2.real, c1.imag+c2.imag);}

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

int main()
{
 int a,b,c,d;
 cin>>a>>b>>c>>d;
 Complex c1(a,b),c2(c,d),c3;
 c3=c1+c2;
 cout<<"c1="; c1.display();
 cout<<"c2="; c2.display();
 cout<<"c1+c2="; c3.display();
 return 0;
}

Answer 1

void display();double real;

Answer 2

说的不是你

Answer 3

什么鬼程序