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C# C# Objects Inheritance Inheritance in Code

LESTER POLICARPIO
LESTER POLICARPIO
2,139 Points
Posted by LESTER POLICARPIO
LESTER POLICARPIO
2,139 Points

Doing a test regarding Inheritance which throws error

Hi,

I am using below code to further test the inheritance topic. All I want is to get the value of the method CheckValue() by using the secondary class Square using inheritance instead of the Polygon class. The problem is that it is throwing an error "the name 'numSides' does not exist in the current context".

using System;

namespace Test_On_Inheritance
{
    class Polygon
    {
        public readonly int NumSides;
        public Polygon(int numSides)
        {
            NumSides = numSides;
        }


        public int CheckValue()
        {
            return NumSides;
        }

        public static void Main()
        {

            Polygon result = new Polygon(4);
            Console.WriteLine(result.CheckValue());

            Square result2 = new Square(5);
            Console.WriteLine(result2.CheckValue());
        }
    }

    class Square : Polygon
    {

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

    }

}

4 Answers

Justin Horner
STAFF
Justin Horner
Treehouse Guest Teacher
Justin Horner
Justin Horner
Treehouse Guest Teacher

Hello Lester,

The reason you're seeing that error is because the Square constructor is passing numSides to the base constructor, which does not existing in the scope of the Square class.

I hope this helps.

LESTER POLICARPIO
LESTER POLICARPIO
2,139 Points
LESTER POLICARPIO
LESTER POLICARPIO
2,139 Points

Thanks Justin,

Isn't below part of doing an inheritance?

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

because base on the video tutorial it was done using this "public MapLocation(int x, int y) : base(x,y)" which also was not in the scope of the MapLocation class?

Justin Horner
Justin Horner
Treehouse Guest Teacher
Justin Horner
Justin Horner
Treehouse Guest Teacher

Yes, passing constructor information to the base constructor is a part of inheritance but in this case the compiler is looking for a variable named numSides within the context of Square but it doesn't exist.

You could add a numSides parameter to the Square constructor and then pass it via base. You can also simply pass a number. I've demonstrated these options below.

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

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

I hope this helps.

LESTER POLICARPIO
LESTER POLICARPIO
2,139 Points
LESTER POLICARPIO
LESTER POLICARPIO
2,139 Points

below are the code for the MapLocation class which only calls the Point class x and y using base (x,y) and did nothing else in this class.

namespace TreehouseDefense { class MapLocation : point {

        public MapLocation(int , int y) : base(x,y)
            {
            }
    }

}

LESTER POLICARPIO
LESTER POLICARPIO
2,139 Points
LESTER POLICARPIO
LESTER POLICARPIO
2,139 Points

Thanks Justin I got it now =)