Function Handling

[edit] Last updated: Fri, 11 May 2012

filter_var

(PHP 5 >= 5.2.0)

filter_var — Filters a variable with a specified filter

Description

mixed filter_var ( mixed $variable [, int $filter = FILTER_DEFAULT [, mixed $options ]] )

Parameters

variable

Value to filter.

filter

The ID of the filter to apply. The Types of filters manual page lists the available filters.

options

Associative array of options or bitwise disjunction of flags. If filter accepts options, flags can be provided in "flags" field of array. For the "callback" filter, callable type should be passed. The callback must accept one argument, the value to be filtered, and return the value after filtering/sanitizing it.


<?php
// for filters that accept options, use this format
$options = array(
    'options' => array(
        'default' => 3, // value to return if the filter fails
        // other options here
        'min_range' => 0
    ),
    'flags' => FILTER_FLAG_ALLOW_OCTAL,
);
$var = filter_var('0755', FILTER_VALIDATE_INT, $options);

// for filter that only accept flags, you can pass them directly
$var = filter_var('oops', FILTER_VALIDATE_BOOLEAN, FILTER_NULL_ON_FAILURE);

// for filter that only accept flags, you can also pass as an array
$var = filter_var('oops', FILTER_VALIDATE_BOOLEAN,
                  array('flags' => FILTER_NULL_ON_FAILURE));

// callback validate filter
function foo($value)
{
    // Expected format: Surname, GivenNames
    if (strpos($value, ", ") === false) return false;
    list($surname, $givennames) = explode(", ", $value, 2);
    $empty = (empty($surname) || empty($givennames));
    $notstrings = (!is_string($surname) || !is_string($givennames));
    if ($empty || $notstrings) {
        return false;
    } else {
        return $value;
    }
}
$var = filter_var('Doe, Jane Sue', FILTER_CALLBACK, array('options' => 'foo'));
?>

Return Values

Returns the filtered data, or FALSE if the filter fails.

Examples

Example #1 A filter_var() example


<?php
var_dump(filter_var('bob@example.com', FILTER_VALIDATE_EMAIL));
var_dump(filter_var('http://example.com', FILTER_VALIDATE_URL, FILTER_FLAG_PATH_REQUIRED));
?>

The above example will output:

string(15) "bob@example.com"
bool(false)


And ... if you also want to handle pre-encoded multi-byte international URL's, you can include the additional code here:



<?php



// convert multi-byte international url's by stripping multi-byte chars

$uri = urldecode($uri) . ' ';

$len = mb_strlen($uri);

if ($len !== strlen($uri))

{

        $convmap = array(0x0, 0x2FFFF, 0, 0xFFFF);

        $uri = mb_decode_numericentity($uri, $convmap, 'UTF-8');

}

$uri = trim($uri);



// now, process pre-encoded MBI's

$regex = '#&([a-z]{1,2})(?:acute|cedil|circ|grave|lig|orn|ring|slash|th|tilde|uml);#i';

$uri_test = preg_replace($regex, '$1', htmlentities($uri, ENT_QUOTES, 'UTF-8'));

if ($uri_test != '') {$uri = $uri_test;}



?>

php at maisqi dot com 27-May-2011 07:11


FILTER_VALIDATE_URL does not support internationalized domain name (IDN). Valid or not, no domain name with Unicode chars on it will pass validation.



We can circumvent this with a home grown solutions, but C code is C code, so I've gone for the code bellow, which builds on filter_var().



<?php

$res = filter_var ($uri, FILTER_VALIDATE_URL);

if ($res) return $res;

// Check if it has unicode chars.

$l = mb_strlen ($uri);

if ($l !== strlen ($uri)) {

    // Replace wide chars by “X”.

    $s = str_repeat (' ', $l);

    for ($i = 0; $i < $l; ++$i) {

        $ch = mb_substr ($uri, $i, 1);

        $s [$i] = strlen ($ch) > 1 ? 'X' : $ch;

    }

    // Re-check now.

    $res = filter_var ($s, FILTER_VALIDATE_URL);

    if ($res) {    $uri = $res; return 1;    }

}

?>



The logic is simple. A non-ascii char is more than one byte long. We replace every one of those chars by "X" and check again.



An alternative will be to punycode the URI before calling filter_var(), but PHP lacks native support for punycode. I think my approach is effective. Please e-mail me if you think otherwise or see room for improvement.

Arvid Bergelmir 11-Jan-2010 05:18


This function will return FALSE on failure but be careful validating boolean values:





Validation failed:


<?php filter_var('abc', FILTER_VALIDATE_BOOLEAN); // bool(false) ?>





Validation correct:


<?php filter_var('0', FILTER_VALIDATE_BOOLEAN); // bool(false) ?>

drtebi at yahoo 24-Nov-2009 11:55


Notice that filter_var with FILTER_VALIDATE_EMAIL does not work if you are trying to get a String from an XML document e.g. via xpath. 



I often use XML files as configuration files and use a function that returns a string from the config file via xpath. While this worked fine before 5.2.11, it doesn't anymore (and shouldn't, since it's an XML Element, not a String). 



To overcome this problem, $variable can be type-casted:



<?php

$variable = fancyXmlGetFunction('from');

filter_var((String) $variable, FILTER_VALIDATE_EMAIL);

?>

suit dot 2009 at rebell dot at 07-Aug-2009 03:11


If PHP >= 5.2 is not present, you can use the regular expression of the original PHP-c-file:





http://svn.php.net/viewvc/php/php-src/trunk/ext/filter/logical_filters.c





Instead of:


<?php filter_var('bob@example.com', FILTER_VALIDATE_EMAIL)); ?>





Just use preg_match(); with a copy of the original regular expression (found in the void "php_filter_validate_email") in logical_filters.c





in fact, this expression (and the original filter-funktion) ignores RFC 5321 (Section 4.5.3.1. Size Limits and Minimums).

tedivm at tedivm dot com 22-Jun-2009 01:28


How to pass options and flags-





<?php


$options = array();


$options['options']['min_range'] = 1;


$options['options']['max_range'] = 10;


$options['flags'] = FILTER_FLAG_ALLOW_OCTAL;


filter_var(3, FILTER_VALIDATE_INT, $options);


?>

Meska 30-Apr-2009 12:08


Just a little filter to validate IP v4 & v6

This little script display result in function of the query

<?php

$ipv6="2a01:e35:aaa4:6860:a5e7:5ba9:965e:cc93";

$ipv4="82.237.3.3";

$fake = "3342423423";

$ipv4priv = "255.255.255.255";

$ipv6priv = "::1";

echo "<pre>";

echo $ipv4;

echo "<br />";

var_dump(filter_var($ipv4,FILTER_VALIDATE_IP));

echo "<br />";

echo $ipv6;

echo "<br />";

var_dump(filter_var($ipv6,FILTER_VALIDATE_IP));

echo "<br />";

echo $fake;

echo "<br />";

var_dump(filter_var($fake,FILTER_VALIDATE_IP));

echo "<br />";

echo $ipv4priv;

echo "<br/>";

echo "FILTER_VALIDATE_IP, FILTER_FLAG_NO_RES_RANGE";

echo "<br />";

var_dump(filter_var($ipv4priv,FILTER_VALIDATE_IP, FILTER_FLAG_NO_RES_RANGE));

echo "<br />";

echo $ipv4priv;

echo "<br/>";

echo "FILTER_FLAG_NO_PRIV_RANGE";

echo "<br />";

var_dump(filter_var($ipv4priv,FILTER_FLAG_NO_PRIV_RANGE));

echo "<br />";

echo $ipv6priv;

echo "<br/>";

echo "FILTER_FLAG_NO_PRIV_RANGE";

echo "<br />";

var_dump(filter_var($ipv6priv,FILTER_FLAG_NO_PRIV_RANGE));

echo "<br />";

echo $ipv6priv;

echo "<br />";

var_dump(filter_var($ipv6priv,FILTER_VALIDATE_IP));



echo "</pre>";



?>

jon dot bertsch at ucop dot edu 24-Mar-2009 07:49


Here's an actual example of the filter syntax with a flag since there doesn't appear to be a one liner for this anywhere:



'hours' => array('filter'=>FILTER_SANITIZE_NUMBER_FLOAT, 'flags' => FILTER_FLAG_ALLOW_FRACTION, 'options'=> '.')

dyer85 at gmail dot com 03-Nov-2008 02:00


Note that when using FILTER_VALIDATE_INT along with the FILTER_FLAG_ALLOW_HEX flag, the string "2f", for example, is not validated successfully, because you must use the "0x" prefix, otherwise, it treats the data as base 10.



The range options are also smart enough to recognize when the boundaries are exceeded in different bases.



Here's an example:



<?php



$foo = '256';

$bar = '0x100';

var_dump(validate_int($foo)); // false, too large

var_dump(validate_int($bar)); // false, too large



function validate_int($input)

{

  return filter_var(

    $input,

    FILTER_VALIDATE_INT,



    // We must pass an associative array

    // to include the range check options.

    array(

      'flags'   => FILTER_FLAG_ALLOW_HEX,

      'options' => array('min_range' => 1, 'max_range' => 0xff)

    )

  );

}



?>

visseraj at gmail dot com 28-Aug-2008 10:31


Here are the other possible flags that you can use:

http://us3.php.net/manual/hu/ref.filter.php

dale dot liszka at gmail dot com 09-Jul-2008 10:15


Here is how to use multiple flags (for those who learn better by example, like me):



<?php

echo "|asdf".chr(9).chr(128)."_123|";

echo "\n";

// "bitwise conjunction" means logic OR / bitwise |

echo filter_var("|asdf".chr(9).chr(128)."_123\n|" ,FILTER_SANITIZE_STRING, FILTER_FLAG_STRIP_LOW | FILTER_FLAG_STRIP_HIGH);



/*

Results:

|asdf    �_123|

|asdf_123|

*/

?>

dale dot liszka at gmail dot com 09-Jul-2008 09:54


Using the FILTER_CALLBACK requires an array to be passed as the options:



<?php

function toDash($x){

   return str_replace("_","-",$x);

} 



echo filter_var("asdf_123",FILTER_CALLBACK,array("options"=>"toDash"));

// returns 'asdf-123'

?>

John 26-Jul-2007 12:35


I managed to get this to work with PHP 5.1.6 on CentOS 5 with minor difficulty.



1) Download the PECL filter package

2) Extract the tarball

3) phpize the directory

4) ./configure

5) make

6) filter-0.11.0/logical_filters.c:25:31: error: ext/pcre/php_pcre.h: No such file or directory

7) find / -name php_pcre.h

8) Make sure php-devel is installed

9) Edit filter-0.11.0/logical_filters.c and replace "ext/pcre/php_pcre.h" with the absolute path of php_pcre.h

10) make

11) make install

12) add "extension=filter.so" to php.ini

13) Restart Apache

add a note

filter_var

Description

Parameters

Return Values

Examples

See Also