regex - 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 ,@#$(@*810 should be stripped. Any ideas?

Edit: I now need this to strip everything but allow dots, so everything but a-z, 1-9, .. Ideas?

Answer 1

$string = preg_replace("/[^a-z0-9.]+/i", "", $string);

Matches one or more characters not a-z 0-9 [case-insensitive], or "." and replaces with ""