PHP Manual
This manual is provided as a courtesy. It is not an official source. Please check php.net for updated information.
(PHP 3, PHP 4, PHP 5)
Returns a version of str with a backslash character (\) before every character that is among these:
. \ + * ? [ ^ ] ( $ )
Note: This function is binary-safe.
See also addslashes(), htmlentities(), htmlspecialchars(), nl2br(), and stripslashes().