#include <iostream>
    #include <stdlib.h>
    using namespace std;
    class Complex
    {
    private:
        int real;
        int img;
    
    public:
        Complex()
        {
            real = img = 0;
        }
    
        Complex(int r, int i)
        {
            real = r;
            img = i;
        }
    
        Complex(Complex &c)
        {
            real = c.real;
            img = c.img;
        }
    
        void putComplex()
        {
            cout << real << "+i" << img<<endl;
        }
    };
    int main()
    {
        system("cls");
        Complex c1;
        Complex c2(3, 5);
        Complex c3(c2);
        c1.putComplex();
        c2.putComplex();
        c3.putComplex();
    
        return 0;
    }
    

2) Step by step what will happen if I remove the "&" from "c" in copy constructor definition? I've heard that it goes to infinite recursion, but I don't understand how.

I'll be happy with any references to read or answers. https://stackoverflow.com/questions/2685854/why-should-the-copy-constructor-accept-its-parameter-by-reference-in-c I've already read this answer and failed to understand from there.