Tom Hines (writinThatCode.com)

I think that is you are going with Linq, then this line is more readable, at least (did not do performance analysis, but it probably performs better as well):

public static string DigitsOnlyTest3(string rawData)
{
return new string(rawData.Where(c => char.IsDigit(c)).ToArray());
}

The reason is because your future reader will wonder why you are generating a range of characters begining with '0' (ohh or zero?), not reusing that enumeration (generate them each time through) even though this is a static set {0,1,2,3,4,5,6,7,8,9}. The contains method is Order-n (I think), so a bunch of 9's take longer than a bunch of zeros to verify, the number 10 in the code will throw readers off (Oh yea, the ascii codes zero through 9 are 10 things).

The above example, assuming the reader realizes that strings are IEnumerable<Char>, is easy to understand that we are picking out the "Digits" in the string.

I do not know what IsDigit actually does, but it could be better than code you/we write for various reasons.

[Please excuse typo's]

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