The PHP addcslash function will returns a string with backslash in-front of the specified characters.
addcslash Examples
<?php $data = "Welcome to PHP Tutorial Website"; echo addcslash($data,'W')."<br />"; echo addcslash($data,'e')."<br />"; ?> Output: \Welcome to PHP Tutorial \Website W\elcom\e to PHP Tutorial Websit\e
<?php $data = "Welcome to PHP Tutorial Website"; echo addcslash($data,'a..z')."<br /> "; echo addcslash($data,'A..Z')."<br /> "; ?> Output: W\e\l\c\o\m \t\o PHP T\u\t\o\r\i\a\l W\e\b\s\i\t\e \Welcome to \P\H\P \Tutorial \Website
Note: Be careful if you choose to escape characters 0, a, b, f, n, r, t and v.
They will be converted to \0, \a, \b, \f, \n, \r, \t and \v, all of which are predefined escape sequences in PHP.