1: 
2: 
3: 
4: 
5: 
6: 
7: 
8: 
9: 
10: 
11: 
12: 
13:

function hilite_php($text) {

	$erg = split('\[/?php\]', $text);
	for($i=1;$i<count($erg);$i=$i+2) {
		$erg2[] = $erg[$i];
	}
	for($i=0;$i<count($erg2);$i++) {
		$text = str_replace('[php]'.$erg2[$i].'[/php]', highlight_string($erg2[$i], true), $text);
	}
	return $text;
}

1: 
2: 
3: 
4: 
5:

$text='Test Text ... blubb [php]<?php phpinfo(); ?>[/php] ..lala[php]<?=$lala ?>[/php]..';

echo hilite_php($text);