$re = '/(?<=<%=).*(?=%>)/m';
$str = '<div>
<% if ( $_createDiv) { %>
<div>Div created!</div>
<% } %>
<h2>
<span><%= $_var1 %></span>
</h2>
<div><%= markdown.toHTML($_var2 ) %></div>
<div><%= $_var3 +\' more text \' + $_var4 %></div>
</div>';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php