Remove all characters except letters and numbers from a string

If you want to strip a string of all symbols and characters other than alphanumeric letters and numbers then use this. It will take a string and erase / delete any non-alphanumeric characters, and then output a clean version without the unwanted characters.

<?php
$string = "This text and numbers 12345 and symbols !£$%^&";
$new_string = ereg_replace("[^A-Za-z0-9]", "", $string);
echo $new_string
?>