Code:
#include <iostream>
using namespace std;

class complex
{
      public:
             double real_dio;
             double imag_dio;
             complex(double r, double i);
             void info(){cout<<" "<<real_dio<<" / "<<imag_dio<<endl;}
             
};

complex::complex(double r, double i)        // konstruktor
{
                        real_dio = r;
                        imag_dio = i;
}

complex operator+(const complex l, const complex d)
{
       return complex(l.real_dio + d.real_dio, l.imag_dio + d.imag_dio);
}

int main()
{
    
    complex a(2.0, 3.0);
    complex b(3.0, 2.0);
    
    complex z = a + b;
    
    complex y = a.operator+(b); // ne radi!!!
    
    
    system("pause>0"); return 0;
    }