Advanced Filters for Beginners to PHP

Detect whether a number is within a range

The following example uses the filter_var() function to detect whether an INT type variable is within 1 to 200 :

<?php
	header("Content-type: text/html; charset=utf-8");//设置编码

	$int = 122;
	$min = 1;
	$max = 200;

	if (filter_var($int, FILTER_VALIDATE_INT, array("options" => array("min_range"=>$min, "max_range"=>$max))) === false) {
	    echo("变量值不在合法范围内");
	} else {
	    echo("变量值在合法范围内");
	}
?>

Detect IPv6 address

The following example uses the filter_var() function to detect whether a $ip variable is an IPv6 address:

<?php
	header("Content-type: text/html; charset=utf-8");//设置编码
	$ip = "2001:0db8:85a3:08d3:1319:8a2e:0370:7334";
	if (!filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6) === false) {
	    echo("$ip 是一个 IPv6 地址");
	} else {
	    echo("$ip 不是一个 IPv6 地址");
	}
?>

Detect URL - must contain QUERY_STRING (query string)

The following example uses the filter_var() function to detect whether $url contains query characters String:

<?php
	header("Content-type: text/html; charset=utf-8");//设置编码
	$url = "http://www.baidu11.com.cn";
	if (!filter_var($url, FILTER_VALIDATE_URL, FILTER_FLAG_QUERY_REQUIRED) === false) {
	    echo("$url 是一个合法的 URL");
	} else {
	    echo("$url 不是一个合法的 URL");
	}
?>

Remove characters with ASCII values ​​greater than 127

The following example uses the filter_var() function to remove ASCII from the string Characters with a value greater than 127, it can also remove HTML tags:

<?php
$str = "<h1>Hello WorldÆØÅ!</h1>";

$newstr = filter_var($str, FILTER_SANITIZE_STRING, FILTER_FLAG_STRIP_HIGH);
echo $newstr;
?>