using System.Text.RegularExpressions;
using System;

public class Kata
{
  public static string Vowel2Index(string str)
  {
    string SwitcherooString = str;
    Regex vowels = new Regex(@"[aeiou]", RegexOptions.IgnoreCase);
    MatchCollection WhereThoseVowelsAt = vowels.Matches(str);
    foreach(Match match in WhereThoseVowelsAt)
    {
      SwitcherooString.Replace(match.Value,Convert.ToString(match.Index));
    }
    return SwitcherooString;
  }
}

Looks like it should work, but the Replace line isn't running at all. Any tips?

So your code isn't working due to this error?
Mine worked just fine, it just had that error as well.
Didn't seem to affect it at all, though, so I submitted it anyways.

Not only that but I popped it into Visual Studio and it says it should run just fine (no StartIndex error)
What gives?

I thought it was pretty easy as well, and I did C#

Though I suppose it's up to the mods. They've been on this site longer, they're probably better at gauging difficulty than we are

Completed kata just fine, but recieved this warning when doing random tests:

tests/Fixture.cs(37,17): warning CS0219: The variable 'Tests' is assigned but its value is never used

Marking as possible issue, but it could be totally inconsequential

It should be. I took all the code in the box and pasted it onto the doc as is.

Although, I didn't try to paste it into Visual Studio to confirm if anything was wrong with the formatting.

About the Markdown boxes, I assumed they weren't used since parts of my code were indeed being placed in markdown without my input and I assumed that if it was working the entire thing would go into a markdown box automatically.

So, I went to Hint 2 and had a look through there and the Brilliant link posted lower down about fast Fibonacci calculation, went and grabbed a bunch of other code (namely Matrix Multiplication) and threw it all together and got about 20 errors, most of which were telling me that I needed like 2 or 3 different characters for the exact same space (in the code that I wrote myself so I know it wasnt a formatting issue with the Matrix Multiplication code I stol- I BORROWED. I did not steal it!)

Something that fails this spectacularly must be fundametnally wrong and thus I get the feeling that I'm going about this the wrong way. Any tips on how to proceed?

(And before you start with the whole 3 kyu shpiel, I know, I'm going to leave this one on the backburner already but I don't want to hear any "You should do some easier ones, dumbass")