Examples
PHP Manual

Validation

Example #1 Validating email addresses with filter_var()

<?php
$email_a 
'joe@example.com';
$email_b 'bogus';

if (
filter_var($email_aFILTER_VALIDATE_EMAIL)) {
    echo 
"This (email_a) email address is considered valid.";
}
if (
filter_var($email_bFILTER_VALIDATE_EMAIL)) {
    echo 
"This (email_b) email address is considered valid.";
}
?>

The above example will output:

This (email_a) email address is considered valid.

Example #2 Validating IP addresses with filter_var()

<?php
$ip_a 
'127.0.0.1';
$ip_b '42.42';

if (
filter_var($ip_aFILTER_VALIDATE_IP)) {
    echo 
"This (ip_a) IP address is considered valid.";
}
if (
filter_var($ip_bFILTER_VALIDATE_IP)) {
    echo 
"This (ip_b) IP address is considered valid.";
}
?>

The above example will output:

This (ip_a) IP address is considered valid.


Examples
PHP Manual