PHP echo $_SERVER['PHP_SELF'] with added variable?

Question

Just want to do $_SERVER['PHP_SELF'] as a link with ?logout=1 appended to it.

<a href="<?php echo ''$_SERVER['PHP_SELF']'.logout=1' ?>" id="add"><input type="button" value="LOGOUT" /></a>

gives

Parse error: syntax error, unexpected T_VARIABLE, expecting ',' or ';' in F:\export\srv\www\vhosts\main\htdocs\php\assign3\m_a2_functions.php on line 90

Answer 1

Change:

<?php echo ''$_SERVER['PHP_SELF']'.logout=1' ?>

To:

<?php echo $_SERVER['PHP_SELF'], '?logout=1' ?>

Answer 2

<a href="<?php echo $_SERVER['PHP_SELF'] . '?logout=1' ?>" id="add">

Answer 3

have you tried:

<?php echo($_SERVER['PHP_SELF'] . "?logout=1") ?>