小弟我从C转C++有个问题请教大家 - C/C++ / C++ 语言

C/C++ code:
#include <iostream>
using namespace std;


class Complex
{
private:
int real;
int image;
public:
Complex ()
{
real = 0;
image = 0;
}
Complex (int n,int i)
{
real = n;
image = i;
}
Complex operator + (Complex &c1,Complex &c2)
{
return (c1.real+c2.real,c1.image+c2.image);
}
void display ()
{
cout<<real<<':'<<image;
}
};



int main()
{
Complex c1(2,3),c2(3,4),c3;
c3 = c1 + c2;
c3.display();
return 0;
}

小弟我从C转C++，学到运算符重载就出问题了，请大家帮我看看
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