PHP Filters Advanced

Validate an Integer Within a Range

The following example uses the filter_var() function to check if a variable is both of type INT, and between 1 and 200:

Example

<?php
$int = 122;
$min = 1;
$max = 200;

if (filter_var($int, FILTER_VALIDATE_INT, array("options" => array("min_range"=>$min, "max_range"=>$max))) === false) {
    echo("Variable value is not within the legal range");
} else {
    echo("Variable value is within the legal range");
}
?>

Validate IPv6 Address

The following example uses the filter_var() function to check if the variable $ip is a valid IPv6 address:

Example

<?php
$ip = "2001:0db8:85a3:08d3:1319:8a2e:0370:7334";

if (!filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6) === false) {
    echo("$ip is a valid IPv6 address");
} else {
    echo("$ip is not a valid IPv6 address");
}
?>

Validate URL - Must Contain QueryString

The following example uses the filter_var() function to check if the variable $url is a URL with a querystring:

Example

<?php
$url = "https://www.w3schools.com";

if (!filter_var($url, FILTER_VALIDATE_URL, FILTER_FLAG_QUERY_REQUIRED) === false) {
    echo("$url is a valid URL");
} else {
    echo("$url is not a valid URL");
}
?>

Remove Characters With ASCII Value > 127

The following example uses the filter_var() function to sanitize a string. It will both remove all HTML tags, and all characters with ASCII value > 127, from the string:

Example

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

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

Complete PHP Filter Reference

For a complete reference of all filter functions, go to our complete PHP Filter Reference. Check each filter to see what options and flags are available.

The reference contains a brief description, and examples of use, for each function!

Credit: www.w3schools.com