How to add and remove backslashes before quotation marks in PHP

$str=$_POST["str"];//Read the content of str and assign it to the $str variable
if(get_magic_quotes_gpc())//If get_magic_quotes_gpc() is turned on
 {
$str=stripslashes($str);//Process the string
}

After modification, the PHP program tested normally both locally and on the website. Related Reading : How to add backslash before php quotes (remove backslash in PHP)