#include<iostream>
using namespace std;
class complex
{
    public:
        complex(){real=0;imag=0;}
        complex(double r,double i){real=r;imag=i;}
        friend complex operator+(complex &c1,complex &c2);
        void display();
    private:
        double real;
        double imag;
};
complex operator+(complex &c1,complex &c2)
{
    return(c1.real+c2.real,c1.imag+c2.imag);
}
void complex::display()
{
    cout<<real<<"+"<<imag<<"i"<<endl;
}
int main()
{
    complexc1(3,4),c2(4,5),c3;
    c3=c1+c2;
    c3.display();
}
[color=FF0000][size=6][size=4]这个程序在VC++6.0里编译的错误怎么解决啊？[/size][/size][/color]