Комментарии к коду

#include <iostream>
using namespace std;
class Complex {
    double re, im;                  
    public:
        Complex(double a_re=0, double a_im=0)   
            {re = a_re; im = a_im; }
    void set_re (double a_re) { re = a_re; } 
    void set_im (double a_im) { im = a_im; }
    Complex operator = (Complex  op );
    Complex operator + (Complex  op );
//Complex operator - (Complex  & op );
    Complex operator - ();  
    bool operator ==(Complex  op);
    friend ostream& operator <<(ostream& out,Complex op);
};
    ostream& operator <<(ostream& out,Complex op)
{
    out<<op.re;
    if (op.im>0) out<<"+";
    if (op.im!=0) out<<op.im<<"i";
    return out;
}
    Complex Complex::operator = (Complex  op )
{
    re=op.re;
    im=op.im;
    return *this;
}
    bool Complex::operator ==(Complex op)
{
    if (re==op.re && im==op.im) return true;
        else return false;
}
    Complex Complex::operator + (Complex  op )
{
    Complex temp;
    temp.re=re+op.re;
    temp.im=im+op.im;
    return temp;
}
    Complex Complex::operator - ()
{
    re=-re;
    im=-im;
    return *this;
}
 
    int main()
{Complex p1(1,2), p2(3,1),p3,p4(5);
    p3=p1+p2;
    cout << "p3=" <<p3<< endl;
    cout << "-p3=" <<-p3<< endl;
    cout << "p1==p2 " <<(p1==p2)<< endl;
    cout << "p4=" <<p4<< endl;
    p4=p1+2;
    cout << "p1+2=" <<p4<< endl;
    return 0;
}