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

When there is no order to work on you could use a dictionary to keep the counts:

String input = "AABCD";
var result = new Dictionary(26);
var chars = input.ToCharArray();
foreach (var c in chars)
{
    if (!result.ContainsKey(c))
    {
        result[c] = 0; // initialize the counter in the result
    }
    result[c]++;
}

foreach (var charCombo in result)
{
    Console.WriteLine("{0}: {1}",charCombo.Key, charCombo.Value);   
}