Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

C# C# Objects Inheritance Inheritance

Posted by Kimmo Ojala
.a{fill-rule:evenodd;}techdegree
Kimmo Ojala
Python Web Development Techdegree Student 8,257 Points

How to pass an argument to base constructor

Hi,

There must be something wrong with my code because I get an error message. I'm trying to initialize the numSides parameter of the child class Square by passing 4 to the parent class constructor. What am I doing wrong?

BR, Kimmo

Polygon.cs 
namespace Treehouse.CodeChallenges
{
     class Square : Polygon
     {
            public readonly int SideLength;

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

    class Polygon
    {
        public readonly int NumSides;

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

1 Answer

Steven Parker
Steven Parker
241,783 Points
Steven Parker
Steven Parker
241,783 Points

Right technique, wrong value.

When they say "by passing 4 to the parent class constructor", they mean 4 — literally ("base(4)").

Also, Square should only take one argument. And you may need to define it after Polygon.

Kimmo Ojala
.a{fill-rule:evenodd;}techdegree
Kimmo Ojala
Python Web Development Techdegree Student 8,257 Points

Thanks Steven. The solution was so literal I just couldn't think of it. Kind of funny, what I tried didn't look right to me, but I would have never guessed that they mean literally what they say. Thanks again!