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# Inheritance- initializing the base class

I think i did my best, can somebody help me spit my error?

Polygon.cs
```namespace Treehouse.CodeChallenges
{
class Polygon
{

public Polygon(int numSides)
{
NumSides = numSides;

}
}

class Square: Polygon
{

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

}

}
```

Thanks tree House Community. It is sinking in to me now :) Shout out to Luke, Alexander and Ford!

Hello,

You are calling the Square constructor in the Square constructor. Which is why this is not passing

```namespace Treehouse.CodeChallenges
{
class Polygon
{

public Polygon(int numSides)
{
NumSides = numSides;

}
}

class Square: Polygon
{
//You got everything correct up to this point
//You want to create the Square constructor as follows:
//you want to give the square constructor a parameter for sideLength AND every time you call the square constructor
//automatically call the Polygon Construcotr 'Polygon(int numsides)' since a square always has 4 sides, you enter 4.
//all 'base(4) does is -> Polygon(4) to the same time you call the Square constructor
public Square(int sideLength): base(4)
{
SideLength = sideLength;
}

}

//you could also create a triangle the same way
class Triangle: Polygon
{

public Triangle(int sideLength):base(3)
{
SideLength = sideLength
}
}

}

Square mySquare = new Square(5); //a square with 5 sides
mySquare.SideLength // will return 5
mySquare.numsides //will return 4

Triangle myTriangle = new Triangle(5);
myTriangle.SideLength //will return 5
myTriangle.numsides //will return 3
```

Hope this makes a bit of sense understanding this

ok you are a lot closer in this example vs. other question.

on the line

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

you do not need the type on the base class. and this is where you define the number of sides.

thing of the area right after the ":" in

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

as calling the parent constructor.

inside the constructor for Square you should only be working with the SideLength.

the number of sides is defined in the call to the base classes.