add 2 complex return,arguments C++

/*add 2 complex numbers */
#include<iostream.h>
#include<conio.h>

class complex       //class declaration
{
	private : float real;
			  float imag;
	public : void read();
			 void display();
			 complex sum(complex);
};
void complex :: read()
{
	cout<<"Enter value for real part: ";
	cin>>real;
	cout<<"Enter value for imaginary part: ";
	cin>>imag;
}
 complex complex :: sum(complex x)
{
	real=real+x.real;
	imag=imag+x.imag;
	return x;
}
void complex :: display()
{
	cout<<real<<"+"<<imag<<"i"<<endl;
}
int main()
{
	complex r1,r2,r3;
	clrscr();
	r1.read();
	r2.read();
	cout<<"Before Addition:\n";
	r1.display();
	r2.display();
	r3=r1.sum(r2);
	cout<<"After Addition:\n";
	r1.display();
	getch();
	return 0;
}