Question

Does anyone know a way in c# to find given a very large string to find random text sections with are greater than 25 continues chars that are alphanumeric?

I’ve tried looping though each char but it is too slow.

Answer 1

Use regular expressions:

MatchCollection matches = Regex.Matches(inputString, @"\w{25,}");
foreach(Match match in matches)
{
    Console.WriteLine(match.Value);
}

\w means “any alphanumeric character”, and {25,} means “at least 25 repetitions”