Inheritance of class

[hihihs]

I try to learn inheritance by myself, however, I do not know where is the error in this code.

I try to print:

Rectangle: length = 8 width = 3
24
Square: side = 5
25

  #include <iostream>

using namespace std;

class Rectangle
{
private:
    int length;
    int width;
public:
    Rectangle();
    Rectangle(int a, int b);
    int getlength() const;
    int getwidth() const;
    virtual int area();

};


Rectangle::Rectangle()
{
}

Rectangle::Rectangle(int a, int b):length(a), width(b)
{
}

int Rectangle::getlength() const
{
    return length;
}

int Rectangle :: getwidth() const
{
    return width;
}

int Rectangle :: area()
{
    return length * width;
}

ostream& operator<<(ostream& out,const Rectangle& R)
{
    out <<"Rectangle: length = " << R.getlength() << " " << "width = " << R.getwidth();
    return out;
}


class Square : Rectangle
{
private:
    int side;
public:
    Square();
    Square(int a);
    int getside() const;
    int area();
};

Square::Square()
{
}

Square::Square(int a): Rectangle(a,a)
{
}

int Square :: area()
{
    return side * side;
}
int Square::getside() const
{
    return side;
}


ostream& operator<<(ostream& out,const Square& S)
{
    out <<"Square: side = " << S.getside();
    return out;
}


int main()
{
    Rectangle R(8,3);
    cout << R << endl;;
    cout << R.area() << endl;
    Square S(5);
    cout << S << endl;
    cout << S.area() << endl;
}

[rafae11]

you just forgot to initialize side.

Square::Square(int a): Rectangle(a,a)
{
    side = a;
}

[hihihs]

Thank you.

[Peter87]

Shouldn't you also be initializing the variables to some default value (e.g. 0) in the default constructors?