Find Nth occurrence of a character in a string

Question

I need help with creating a C# method that returns the index of the Nth occurrence of a character in a string.

For instance, the 3rd occurrence of the character 't' in the string "dtststxtu" is 5.
(Note that the string has 4 ts.)

Answer 1

public int GetNthIndex(string s, char t, int n) {     int count = 0;     for (int i = 0; i < s.Length; i++)     {         if (s[i] == t)         {             count++;             if (count == n)             {                 return i;             }         }     }     return -1; } 

That could be made a lot cleaner, and there are no checks on the input.

Answer 2

There is a minor bug in previous solution.

Here is some updated code:

s.TakeWhile(c => (n -= (c == t ? 1 : 0)) > 0).Count();