为什么结果是This is a link to http://www.wjigilmore.com/.?

<?php

$text = "This is a link to http://www.wjigilmore.com/.";

echo preg_replace("/http:\/\/(.*)\//","<a href = \"\${0}\">\${0}</a>",$text);

?>

不是应该是This is a link to

<a herf ="http:// www.wjigilmore.com/"> http://www.wjigilmore.com/<a/>.吗？