Removing special characters

Is there a PHP built-in function to retrieve only the alphanumeric characters from a given string? I know that I can check for alphanumeric characters using the function ctype_alphanum () but it won't retrieve the alphanum characters. I also know that I can use str_replace to replace an array of special characters such as the example below: $str = "I*m using <html tags> with special/chars like | how to get rid of it???"; $removeChars = array ('*','?','|','>','<','/','\\'); $str = str_replace ($removeChars, "", $str); However, could there be a specific function for just retrieving alphanumeric characters? or a specific function for just stripping special characters? Or maybe a better way to do those things from the example given above? Thanks in advance. :) ___________________________ PHP Version: 4.4.0