Altrernate TR color Using Pregmatch

<style type=”text/css”>
tr.diff {
background: red;
}
</style>
<?php
$text = “<table border=’1′ width=’200′>
<tr><td>&nbsp;</td></tr>
<tr><td>&nbsp;</td></tr>
<tr><td>&nbsp;</td></tr>
<tr><td>&nbsp;</td></tr>
<tr><td>&nbsp;</td></tr>
<tr><td>&nbsp;</td></tr>
</table>”;
$text = preg_replace(”/((<tr>.*?<\/tr>[^<]*<tr)(>.*?<\/tr>))/s”, “$2 class=’diff’$3″, $text);
echo $text;
?>