PHP正则表达式(常用的7个例子)

1、验证E-mail

 用filer_var 比用正则匹配更加好

if (filter_var('test+email@ansoncheung', FILTER_VALIDATE_EMAIL)) {
    echo "Your email is ok.";
} else {
    echo "Wrong email address format.";
}

2、验证用户名(验证用户名5-20之间)

$username = "user_name12";
if (preg_match('/^[a-z\d_]{5,20}$/i', $username)) {
    echo "Your username is ok.";
} else {
    echo "Wrong username format.";
}

3、验证ip地址

$IP = "198.168.1.78";
if (preg_match('/^(([1-9]?[0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]).){3}([1-9]?[0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$/',$IP)) {
    echo "Your IP address is ok.";
} else {
    echo "Wrong IP address.";
}

4、验证邮编

$zipcode = "12345-5434";
 if (preg_match("/^([0-9]{5})(-[0-9]{4})?$/i",$zipcode)) {
 echo "Your Zip code is ok.";
 } else {
 echo "Wrong Zip code.";
 }

5、验证域名

$url = "http://ansoncheung.tk/";
 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.";
 }

$url = "http://ansoncheung.tk/articles";
 preg_match('@^(?:http://)?([^/]+)@i', $url, $matches);
 $host = $matches[1];
echo $host;

$text = "Sample sentence from AnsonCheung.tk, regular expression 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;