Overloading I/O Operators

This givens an example showing overloading I/O operators (in a very simple way). The complete code for this example can be found in overloadIO.cpp

Main method

int main() {
    Point p, q;

    cout << "enter a point: ";
    cin >> p;
    
    cout << "you entered: " << p << endl;

    cout << "enter another point: ";
    cin >> q;
    
    cout << "you entered: " << q << endl;

    return 0;
}

Point class

class Point {

    friend ostream & operator<<(ostream & out, const Point & p);

    friend istream & operator>>(istream & in, Point & p);

  public:

    // constructors
    Point(): x(0), y(0) { }
    Point(int a, int b): x(a), y(b) { }

    // accessors
    int getX() const { return x; }
    int getY() const { return y; }

    // mutators
    void setX(int newX) { x = newX; }
    void setY(int newY) { y = newY; }

  private:

    int x, y;
};

Overload <<

ostream & operator<<(ostream & out, const Point & p) {
    out << "(" << p.x << "," << p.y << ")";
    return out;
}

Overload >>

istream & operator>>(istream & in, Point & p) {

    char ch;
    int x, y;


    in.get(ch);
    while (ch == ' ' || ch == '\n' || ch == '\t')
        in.get(ch);


    if (ch != '(') { 

        return in;
    }


    in >> x;         // read in x value


    in.get(ch);
    while (ch == ' ' || ch == '\n' || ch == '\t')
        in.get(ch);


    if (ch != ',') {

        return in;
    }
	
	
    in >> y;         // read in y value


    in.get(ch);
    while (ch == ' ' || ch == '\n' || ch == '\t') 
        in.get(ch);


    if (ch != ')') {

        return in;
    }


    // only after the entire point has been read in successfully do we update p
    p.x = x;
    p.y = y;
    return in;
}