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.\n";
}
if (
filter_var($email_bFILTER_VALIDATE_EMAIL)) {
    echo 
"This ($email_b) email address is considered valid.\n";
} else {
    echo 
"This ($email_b) email address is considered invalid.\n";
}
?>

The above example will output:

This (joe@example.com) email address is considered valid.
This (bogus) email address is considered invalid.

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.

Example #3 Passing options to filter_var()

<?php
$int_a 
'1';
$int_b '-1';
$int_c '4';
$options = array(
    
'options' => array(
                      
'min_range' => 0,
                      
'max_range' => 3,
                      )
);
if (
filter_var($int_aFILTER_VALIDATE_INT$options) !== FALSE) {
    echo 
"This (int_a) integer is considered valid (between 0 and 3).\n";
}
if (
filter_var($int_bFILTER_VALIDATE_INT$options) !== FALSE) {
    echo 
"This (int_b) integer is considered valid (between 0 and 3).\n";
}
if (
filter_var($int_cFILTER_VALIDATE_INT$options) !== FALSE) {
    echo 
"This (int_c) integer is considered valid (between 0 and 3).\n";
}

$options['options']['default'] = 1;
if ((
$int_c filter_var($int_cFILTER_VALIDATE_INT$options)) !== FALSE) {
    echo 
"This (int_c) integer is considered valid (between 0 and 3) and is $int_c.";
}
?>

The above example will output:

This (int_a) integer is considered valid (between 0 and 3).
This (int_c) integer is considered valid (between 0 and 3) and is 1.


Examples
PHP Manual