PHP正则表达式(常用的7个例子)_PHP教程

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

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

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

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

$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", &#39;<span style="background:#5fc9f6">\1</span>&#39;, $text);
echo $text;