在WordPress中，如果你想自动转换URL，跳转至超链接页面，你可以利用内置的函数make_clickable()执行此操作。如果你想基于WordPress之外操作该程序，那么你可以参考wp-includes/formatting.php源代码。

<?php
/*
在WordPress中，如果你想自动转换URL，跳转至超链接页面，你可以利用内置的函数make_clickable()执行此操作。如果你想基于WordPress之外操作该程序，那么你可以参考wp-includes/formatting.php源代码。
*/
function _make_url_clickable_cb($matches)
{
    $ret = '';
    $url = $matches[2];

    if (empty($url))
        return $matches[0];
    // removed trailing [.,;:] from URL
    if (in_array(substr($url, -1), array('.', ',', ';', ':')) === true) {
        $ret = substr($url, -1);
        $url = substr($url, 0, strlen($url) - 1);
    }
    return $matches[1] . "<a href=\"$url\" rel=\"nofollow\">$url</a>" . $ret;
}

function _make_web_ftp_clickable_cb($matches)
{
    $ret = '';
    $dest = $matches[2];
    $dest = 'http://' . $dest;

    if (empty($dest))
        return $matches[0];
    // removed trailing [,;:] from URL
    if (in_array(substr($dest, -1), array('.', ',', ';', ':')) === true) {
        $ret = substr($dest, -1);
        $dest = substr($dest, 0, strlen($dest) - 1);
    }
    return $matches[1] . "<a href=\"$dest\" rel=\"nofollow\">$dest</a>" . $ret;
}

function _make_email_clickable_cb($matches)
{
    $email = $matches[2] . '@' . $matches[3];
    return $matches[1] . "<a href=\"mailto:$email\">$email</a>";
}

function make_clickable($ret)
{
    $ret = ' ' . $ret;
    // in testing, using arrays here was found to be faster
    $ret = preg_replace_callback('#([\s>])([\w]+?://[\w\\x80-\\xff\#$%&~/.\-;:=,?@\[\]+]*)#is', '_make_url_clickable_cb', $ret);
    $ret = preg_replace_callback('#([\s>])((www|ftp)\.[\w\\x80-\\xff\#$%&~/.\-;:=,?@\[\]+]*)#is', '_make_web_ftp_clickable_cb', $ret);
    $ret = preg_replace_callback('#([\s>])([.0-9a-z_+-]+)@(([0-9a-z-]+\.)+[0-9a-z]{2,})#i', '_make_email_clickable_cb', $ret);

    // this one is not in an array because we need it to run last, for cleanup of accidental links within links
    $ret = preg_replace("#(<a( [^>]+?>|>))<a [^>]+?>([^>]+?)</a></a>#i", "$1$3</a>", $ret);
    $ret = trim($ret);
    return $ret;
}

原文地址：http://www.cnblogs.com/fuqian/p/16883656.html