Trouble Finding the Average Tongue Length for Frogs For Loop

Question

Hi everyone,

I'm having trouble trying to figure out how to get the challenge. So far I have this:

namespace Treehouse.CodeChallenges { class FrogStats {

    public static double GetAverageTongueLength(Frog[] frogs)
    {

        double sum = 0;

        for (int i = 0; i < frogs.Length; i++)
        {
            Frog sum = frogs[i];

        }
        return sum / frogs.Length;
    }
}

}

I get this error message: FrogStats.cs(13,22): error CS0136: A local variable named sum' cannot be declared in this scope because it would give a different meaning tosum', which is already used in a `parent or current' scope to denote something else Compilation failed: 1 error(s), 0 warnings

The error is the same if I put the return line inside the for loop and if I remove 'Frog' before sum within the for loop. If I were to change the for loop to this:

double sum = 0;

        for (int i = 0; i < frogs.Length; i++)
        {
             sum = frogs[i];

        }
        return sum / frogs.Length;
    }
}

}

I get a error CS0029: Cannot implicitly convert type Treehouse.CodeChallenges.Frog' todouble'

I'm not sure what to do in order to correct this issue and give the challenge's answer. Thoughts?

FrogStats.cs

Frog.cs

namespace Treehouse.CodeChallenges
{
    public class Frog
    {
        public int TongueLength { get; }

        public Frog(int tongueLength)
        {
            TongueLength = tongueLength;
        }
    }
}

Answer 1 · 2016-10-17T01:34:59Z

October 17, 2016 1:34am

The problem in your first example is that you are declaring the sum variable twice and the second time you declare it as a different data type, that is not allowed in C#.

In the second example the problem is that the frogs array is not an array of numbers, it is actually an array of frog objects, so frogs[i] will actually result in a singular Frog object, which is not something that can be stored in a double variable.

If you look at the file for the frog class which is available in the challenge workspace you will see that it has a property called TongueLength, this is where the tongue length of the frog is actually stored.

This means that you have to access it using dot notation like this: frogs[i].TongueLength

In addition to that there is a second problem in your loop which is the fact that you are setting sum equal to the frog object, rather than adding the frog object to it, this means that each time though the loop the sum variable is replaced by the contents of the current frog object rather than having the contents added to sum.

To fix that you have to use the += symbol (which adds the content on the right to the variable on the left) rather than the = symbol (which completely replaces the contents of the variable with the value on the right).

After applying those two fixes to your code you end up with this code:

  double sum = 0;
  for (int i = 0; i < frogs.Length; i++)
  {
    sum += frogs[i].TongueLength;
  }
  return sum / frogs.Length;

Which does what the challenge asks for.

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Tony Lawrence

Tony Lawrence

Trouble Finding the Average Tongue Length for Frogs For Loop

1 Answer

andren

andren

Tony Lawrence

Tony Lawrence