<?php
if ($a == $b)
echo "ab";
?>
<?php if ($a == $b) { ?>
echo "ab";
<?php } else { ?>
echo "c";
<?php } ?>
<?php
echo <<<EOL // <- We use the heredoc operator. Notice 3 times '<'
<div id="menu_show" class="...">
...
</div>
EOL; // End the heredoc block. Has to be the first characters on the line, so don't indent it.
?>