Poor Inheritance example in C#

Question

Im was reading an example of simple inheritence and came across the basic idea that a square is a base type and a rectangle is derived from a square.

The example for setting the square dimensions used a property called Size. The example for the rectangle then went on to use Width and Height.

This didnt make sense in my head, so I coded it.

The problem seems to be that when accessing rectangle, there will always be a confusing property called 'Size' present.

Have I got this right? Or is there a way to hide other classes from seeing Size when looking at rectangle?

public class square
{
    public int Size { get; set; }
    public square(int size)
    {
        this.Size = size;
    }
}

public class rectangle : square
{
    public int Width { get { return base.Size; } set { base.Size = value; } }

    public int Height { get; set; }

    public rectangle(int width, int height)
        : base(width)
    {
        Height = height;
    }
}

Answer 1

You are 100% right that this is backwards inheritance. Instead, you should have a Square class inherit from a Rectangle class, since a square is a special kind of rectangle.

Then, you get something like

public class Rectangle
{
    public int Width { get; private set; }
    public int Height { get; private set; }

    public Rectangle(int width, int height)
    {
        if (width <= 0 || height <= 0)
            throw new ArgumentOutOfRangeException();
        Width = width;
        Height = height;
    }
}

public class Square : Rectangle
{
    public int Size
    {
        get
        {
            return Width;
        }
    }

    public Square(int size)
        : base(size, size)
    {
    }
}