How do I remove all alphanumeric characters from a .NET string using the Regex class?

Question

I've tried new Regex("a-zA-Z0-9").Replace(myString, string.Empty) but apparently that is not correct.

Sebastian Paaske Tørholm · Accepted Answer · 2011-01-14 05:50:56Z

5

The correct regex would be [a-zA-Z0-9].

The regular expression a-zA-Z0-9 matches the literal string a-zA-Z0-9 whereas the character class [a-zA-Z0-9] matches any of the characters in the ranges a-z, A-Z or 0-9.

In addition, these classes have shorthands (sort of).

\d represents the class of digits, that is [0-9].
\w represents the class of alphanumerical characters, as well as underscore, that is [0-9A-Za-z_].

Useful links:

Character classes on Regular-Expressions.info.

answered Jan 14, 2011 at 5:50

Sebastian Paaske Tørholm

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1 Comment

Jake Petroules Over a year ago

Thanks, I knew I was missing something simple. ;) +1

Tim Jarvis · Accepted Answer · 2011-01-14 06:07:10Z

1

Just for laughs you could also do it like this....

string newString = new string(s.Where(c => !char.IsLetterOrDigit(c)).ToArray());

(much, much slower the first time through...then subsequent runs, faster)

answered Jan 14, 2011 at 6:07

Tim Jarvis

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