[Adeline]

验证域名
检验一个字符串是否是个有效域名.

$url = "http://komunitasweb.com/";
if (preg_match('/^(http|https|ftp)://([A-Z0-9][A-Z0-9_-]*(?:.[A-Z0-9][A-Z0-9_-]*)+):?(d+)?/?/i', $url)) {
    echo "Your url is ok.";
} else {
    echo "Wrong url.";
}

从一个字符串中 突出某个单词
这是一个非常有用的在一个字符串中匹配出某个单词 并且突出它，非常有效的搜索结果

$text = "Sample sentence from KomunitasWeb, regex has become popular in web programming. Now we learn regex. According to wikipedia, Regular expressions (abbreviated as regex or

regexp, with plural forms regexes, regexps, or regexen) are written in a formal language that can be interpreted by a regular expression processor";
$text = preg_replace("/b(regex)b/i", '<span style="background:#5fc9f6">1</span>', $text);
echo $text;

突出查询结果在你的 WordPress 博客里就像刚才我说的，上面的那段代码可以很方便的搜索出结果，而这里是一个更好的方式去执行搜索在某个WordPress的博客上打开你的文件 search.php ，然后找到 方法 the_title() 然后用下面代码替换掉它

echo $title;

Now, just before the modified line, add this code:

<?php
    $title     = get_the_title();
    $keys= explode(" ",$s);
    $title     = preg_replace('/('.implode('|', $keys) .')/iu',
        '<strong>\0</strong>',
        $title);
?>

Save the search.php file and open style.css. Append the following line to it:

strong.search-excerpt { background: yellow; }

从HTML文档中获得全部图片
如果你曾经希望去获得某个网页上的全部图片，这段代码就是你需要的，你可以轻松的建立一个图片下载机器人

$images = array();
preg_match_all('/(img|src)=("|')[^"'>]+/i', $data, $media);
unset($data);
$data=preg_replace('/(img|src)("|'|="|=')(.*)/i',"$3",$media[0]);
foreach($data as $url)
{
    $info = pathinfo($url);
    if (isset($info['extension']))
    {
        if (($info['extension'] == 'jpg') ||
        ($info['extension'] == 'jpeg') ||
        ($info['extension'] == 'gif') ||
        ($info['extension'] == 'png'))
        array_push($images, $url);
    }
}

删除重复字母
经常重复输入字母? 这个表达式正适合.

$text = preg_replace("/s(w+s)1/i", "$1", $text);

删除重复的标点
功能同上，但只是面对标点，白白重复的逗号

$text = preg_replace("/.+/i", ".", $text);