quotemeta in PHP

PHP quotemeta() function is utilized to include backslash character( \ ) before some predefined characters in a string.

The predefined characters are :

period ( . )
backslash ( \ )
plus sign ( + )
asterisk ( * )
question mark ( ? )
brackets ( [] )
caret ( ^ )
dollar sign ( $ )
parenthesis ( () )
Syntax:

quotemeta(string)
string : Required.  Defines the input string.   

Tip: This function might be utilized to escape with special meaning, for example (), [], and * in SQL.

Example:

<?php
$input_str  = "Good Morning. (what are you doing?)";
echo quotemeta ($input_str);
?>
The output  will be:
Good Morning\. \(what are you doing\?\)