Extract numbers from string to create digit only string [duplicate]

Answer 1

The question doesn't explicitly state that you just want the characters 0 to 9 but it wouldn't be a stretch to believe that is true from your example set and comments. So here is the code that does that.

        string digitsOnly = String.Empty;
        foreach (char c in s)
        {
            // Do not use IsDigit as it will include more than the characters 0 through to 9
            if (c >= '0' && c <= '9') digitsOnly += c;
        }

Why you don't want to use Char.IsDigit() - Numbers include characters such as fractions, subscripts, superscripts, Roman numerals, currency numerators, encircled numbers, and script-specific digits.

Answer 2

You could write a simple method to extract out all non-digit characters, though this won't handle floating point data:

public string ExtractNumber(string original)
{
     return new string(original.Where(c => Char.IsDigit(c)).ToArray());
}

This purely pulls out the "digits" - you could also use Char.IsNumber instead of Char.IsDigit, depending on the result you wish.