Operator Overloading Full [ friend function ]

// cpp program: Operator overloading [full]  Active: friend methods, Inactive: member methods
// Author: fueanta

#include <iostream>
#include <conio.h> // supported by windows platform only, just ignore for other OS

using namespace std;

class point
{
   int x,y;
public:
    point(int x=0, int y=0):x(x),y(y) {}
    void show();
    // Operator Over-loadings:
    //point operator-();
    friend point operator-(point);
    //point operator+(point);
    friend point operator+(point, point);
    //point operator+(int);
    friend point operator+(point, int);
    void operator=(point);
    // XXX friend void operator=(point, point);
    //point operator+=(int);
    friend point operator+=(point&, int);
    //void operator+=(point);
    friend void operator+=(point&, point);
    //point operator++();
    friend point operator++(point&);
    //point operator++(int);
    friend point operator++(point&, int);
    //bool operator==(point);
    friend bool operator==(point,point);
    friend point operator+(int, point);
    friend ostream & operator << (ostream &, point&);
    friend istream & operator >> (istream &, point&);
};

void point::show()
{
    cout << "X= " << x << "\tY= " << y << endl;
}
/*point point::operator-()
{
    return point(-x,-y);
}*/
point operator-(point i)
{
    return point(-i.x, -i.y);
}
/*point point::operator+(point i)
{
    return point(x+i.x, y+i.y);
}*/
point operator+(point i,point j)
{
    return point(i.x+j.x, i.y+j.y);
}
/*point point::operator+(int i)
{
    return point(x+i, y+i);
}*/
point operator+(point i, int j)
{
    return point(i.x+j, i.y+j);
}
void point::operator=(point i)
{
    x=i.x; y=i.y;
    //return *this; then, return type should be given.
}
/*point point::operator+=(int i)
{
    x+=i; y+=i;
    return *this;
}*/
point operator+=(point& i, int j)
{
    i.x+=j; i.y+=j;
    return i;
}
/*void point::operator+=(point i)
{
    x+= i.x; y+= i.y;
    //return *this; then, return type should be given.
}*/
void operator+=(point& i, point j)
{
    i.x+=j.x; i.y+=j.y;
}
/*point point::operator++()
{
    return point(++x, ++y);
}*/
point operator++(point& i)
{
    return point(++i.x, ++i.y);
}
/*point point::operator++(int)
{
    return point(x++, y++);
}*/
point operator++(point& i,int)
{
    return point(i.x++, i.y++);
}
/*bool point::operator==(point i)
{
    if(x==i.x && y==i.y)
        return true;
    else
        return false;
}*/
bool operator==(point i, point j)
{
    if (i.x==j.x && i.y==j.y)
        return true;
    else
        return false;
}
point operator+(int i, point j)
{
    return point(i+j.x, i+j.y);
}
ostream & operator << (ostream & out, point &i)
{
    out << "X= " << i.x << ", Y= " << i.y << "; ";
    return out;
}
istream & operator >> (istream & in, point &i)
{
    in >> i.x >> i.y;
    return in;
}

int main()
{
    point p1(10,20),p2(20,30),p3;
    p3= -p1;
    p3.show();
    p3= p1+p2;
    p3.show();
    p3= p1+5;
    p3.show();
    p3= p2;
    p3.show();
    p3+= 5;
    p3.show();
    p1+= p2;
    p1.show();
    p2.show();
    p3= ++p1;
    p3.show();
    p1.show();
    p3= p2++;
    p3.show();
    p2.show();
    point p4(31,51);
    p4= 5+p2;
    p4.show();
    if (p1==p4)
        cout << "Equal." << endl;
    else
        cout << "Not Equal." << endl;
    cout << "P1: " << p1 << " P2: " << p2 << endl;
    cout << "Give p3: x and y\n";
    cin >> p3;
    cout << "P3: " << p3 << endl;
    getch(); // assosiated with conio.h
    return 0;
}