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C# C# Objects Inheritance Inheritance

Posted by Allon de Veen
Allon de Veen
2,284 Points

inner class

What's the deal with that question about inner class? The course hasn't covered that yet. I can't see what I did wrong.

Polygon.cs 
namespace Treehouse.CodeChallenges
{
    class Polygon
    {
        public readonly int NumSides = 4;

        public Polygon(int numSides)
        {
            NumSides = numSides;
        }
    }

    class Square : Polygon
    {
        public readonly int SideLength;

        public Square(int sideLength) : base(numSides)
        {

        }
    }
}

2 Answers

Steven Parker
Steven Parker
231,269 Points
Steven Parker
Steven Parker
231,269 Points

I don't think the challenge mentions "inner class". But it does say that the new field "SideLength" should be initialized using the constructor. That means it should have a value set similar to how "Polygon" sets "NumSides" in its constructor. So you still need to do that part.

Also, when they say "Use base to initialize NumSides to 4" they mean you should literally pass a 4 to base. It will handle setting "NumSides" for you.

Allon de Veen
Allon de Veen
2,284 Points
Allon de Veen
Allon de Veen
2,284 Points

This is the assignment:

The Polygon class represents a 2 dimensional shape. It has a public field named NumSides. Create a new type of polygon called Square. It should have a public readonly field named SideLength that’s initialized using the constructor. Use base to initialize NumSides to 4.

This is my code:

namespace Treehouse.CodeChallenges
{
    class Polygon
    {
        public readonly int NumSides;

        public Polygon(int numSides)
        {
            NumSides = 4;
        }
    }

    class Square : Polygon
    {
        public readonly int SideLength;

        public Square(int sideLength) : base(numSides)
        {
            SideLength = 4;
        }
    }
}

This is the error message I am getting:

Bummer! Did you define your Square class as an inner class of the Polygon class? Be sure to define the Square class before or after the definition for the Polygon class.

As you can see the challenge didn't mention inner class but the error message did. With this new code it still doesn't work.

Andrew Sykes
Andrew Sykes
9,286 Points
Andrew Sykes
Andrew Sykes
9,286 Points 
namespace Treehouse.CodeChallenges
{
    class Polygon
    {
        public readonly int NumSides;

        public Polygon(int numSides)
        {
            NumSides = numSides;
        }
    }

    class Square : Polygon
    {
        public readonly int SideLength;

        public Square(int sideLength) : base(4)
        {
            SideLength = sideLength;
        }
     }
}

The NumSides parameter is satisfied during constructing this new sub-class of Square by passing '4' directly to base. The new parameter "SideLength" is unique to your subclass Square.