1. filter_var():- filter_var() function is used to check if the given variable is a valid IPv6 Address

<?php

$ip = "2001:cdba:0000:0000:0000:0000:3257:9652";

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

output:  Valid IPv6 address

2. filter_var():-   filter_var() is used to check if the given variable is url with a querystring.

<?php

$url = "http://www.findnerd.com";

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

?>

output:  URL is not with a querystring

3. filter_var():-   filter_var() is used to check whether the given variable is INT, and between 10 and 100.

<?php

$int = 111;
$min = 5;
$max = 100;

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

else
{
    echo("Given variable is within the legal range");
}

?>

output:   Given variable is not within the legal range