Testing for repeated characters in a string

Question

I\'m doing some work with strings, and I have a scenario where I need to determine if a string (usually a small one < 10 characters) contains repeated characters.

Answer 1

Since you're using 3.5, you could do this in one LINQ query:

var results = stringInput
  .ToCharArray() // not actually needed, I've left it here to show what's actually happening
  .GroupBy(c=>c)
  .Where(g=>g.Count()>1)
  .Select(g=>new {Letter=g.First(),Count=g.Count()})
;

For each character that appears more than once in the input, this will give you the character and the count of occurances.