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###### Cliffton Caro

655 Points# Initialize Polygon from base with 4

I am currently very confused of what i am being asked for.

Im following the examples in the videos but it doesn't really go into bases, or how to initialize them. Or at least im not understanding it.

I think what i have is correct so far. but when i run the code, it says, "Bummer, did you create a class within a class? Square should be before or after the class Polygon."

I think i created the Square class correctly, so I'm confused why i would get this error.

If someone could assist that would be great.

Thanks

```
namespace Treehouse.CodeChallenges
{
class Polygon
{
public readonly int NumSides;
public Polygon(int numSides)
{
NumSides = numSides;
}
}
class Square : Polygon
{
public readonly int SideLength;
public Polygon(int numSides) : base Square(SideLength)
{
SideLength = sideLength;
}
}
}
```

## 1 Answer

###### Jennifer Nordell

Treehouse TeacherHi there, Cliffton Caro ! It looks like you're off to a terrific start. But there's a few things going on here. First, the name of the constructor should be the same as the name of the *class*. So instead of `public Polygon(int numSides)`

you should be using `public Square(int sideLength)`

. And it should take the *length* of the sides. Not the number of sides it should have. There's no scenario where a square has three sides or 8 sides. If it does, it's no longer a square

It's the `Polygon`

or "base class" that takes the number of sides. And a square should always send in 4 sides. If this class were `Triangle`

it should send 3 into the Polygon class. A triangle is a polygon with three sides. A square is a polygon with four sides. You'll want to send that into `base`

directly.

```
class Square : Polygon // Square inherits from Polygon. It is a type of polygon.
{
public readonly int SideLength;
public Square(int sideLength) : base(4) // pass in 4 because a square is always 4 sides
{
SideLength = sideLength; // set the public field to whatever was passed in to determine how long the sides are
}
}
```

A square is a *kind/type* of polygon. So we set that up. The *constructor* of the square takes the side length. For example, at the moment I create a new square, I give it dimensions by including the side length. A square is defined as having four sides of equal length. Creating a `Square(10)`

should give me a polygon with four sides each having a side length of 10. The unit of measurement is ambiguous here, but it has some length of 10 of some unit.

Hope this helps!

## Cliffton Caro

655 Points## Cliffton Caro

655 PointsThank you for the response! This helped me me understand what the heck was going on.