<?php
function replace_url ($content) {
	if (empty($content)) return;

	//给URL地址加上 <a> 链接
	$preg = ‘/(?:http:\/\/)?([\w.]+[\w\/]*\.[\w.]+[\w\/]*\??[\w=\&\+\%]*)/is‘;
	$content = preg_replace($preg, ‘<a href=http://www.mamicode.com/"http://1" target="_blank">/1‘, $content);>