php源码：自动识别文本中的链接

function text2links($str='') {
if(!preg_match('/(http|www\.|@)/i', $str)) { return $str; }
$lines = explode("<br />", $str); $new_text = '';
while (list($k,$l) = each($lines)) { 
// replace links:
	$l = preg_replace("/([ \t]|^)www\./i", "\\1http://www.", $l);

	$l = preg_replace("/([ \t]|^)ftp\./i", "\\1ftp://ftp.", $l);

	$l = preg_replace("/(http:\/\/[^ )!]+)/i", "<a href=\"\\1\">\\1</a>", $l);

	$l = preg_replace("/(https:\/\/[^ )!]+)/i", "<a href=\"\\1\">\\1</a>", $l);

	$l = preg_replace("/(ftp:\/\/[^ )!]+)/i", "<a href=\"\\1\">\\1</a>", $l);

	$l = preg_replace("/([-a-z0-9_]+(\.[_a-z0-9-]+)*@([a-z0-9-]+(\.[a-z0-9-]+)+))/i", "<a href=\"mailto:\\1\">\\1</a>", $l);

	$new_text .= $l.'<br />';
}

return $new_text;
}