Stripping everything but alphanumeric chars from a string in PHP

Question

I\'d like a regexp or other string which can replace everything except alphanumeric chars (a-z and 0-9) from a string. All things such as ,@#

Answer 1

I like using [^[:alnum:]] for this, less room for error.

preg_replace('/[^[:alnum:]]/', '', "(ABC)-[123]"); // returns 'ABC123'