Validate filters

Listing of filters for validation
ID Name Options Flags Description
FILTER_VALIDATE_BOOLEAN "boolean" default FILTER_NULL_ON_FAILURE

Returns TRUE for "1", "true", "on" and "yes". Returns FALSE otherwise.

If FILTER_NULL_ON_FAILURE is set, FALSE is returned only for "0", "false", "off", "no", and "", and NULL is returned for all non-boolean values.

FILTER_VALIDATE_EMAIL "validate_email" default FILTER_FLAG_EMAIL_UNICODE

Validates whether the value is a valid e-mail address.

In general, this validates e-mail addresses against the syntax in RFC 822, with the exceptions that comments and whitespace folding and dotless domain names are not supported.

FILTER_VALIDATE_FLOAT "float" default, decimal FILTER_FLAG_ALLOW_THOUSAND Validates value as float, and converts to float on success.
FILTER_VALIDATE_INT "int" default, min_range, max_range FILTER_FLAG_ALLOW_OCTAL, FILTER_FLAG_ALLOW_HEX Validates value as integer, optionally from the specified range, and converts to int on success.
FILTER_VALIDATE_IP "validate_ip" default FILTER_FLAG_IPV4, FILTER_FLAG_IPV6, FILTER_FLAG_NO_PRIV_RANGE, FILTER_FLAG_NO_RES_RANGE Validates value as IP address, optionally only IPv4 or IPv6 or not from private or reserved ranges.
FILTER_VALIDATE_MAC "validate_mac_address" default   Validates value as MAC address.
FILTER_VALIDATE_REGEXP "validate_regexp" default, regexp   Validates value against regexp, a Perl-compatible regular expression.
FILTER_VALIDATE_URL "validate_url" default FILTER_FLAG_SCHEME_REQUIRED, FILTER_FLAG_HOST_REQUIRED, FILTER_FLAG_PATH_REQUIRED, FILTER_FLAG_QUERY_REQUIRED Validates value as URL (according to » http://www.faqs.org/rfcs/rfc2396), optionally with required components. Beware a valid URL may not specify the HTTP protocol http:// so further validation may be required to determine the URL uses an expected protocol, e.g. ssh:// or mailto:. Note that the function will only find ASCII URLs to be valid; internationalized domain names (containing non-ASCII characters) will fail.

Note:

As of PHP 5.4.11, the numbers +0 and -0 validate as both integers as well as floats (using FILTER_VALIDATE_FLOAT and FILTER_VALIDATE_INT). Before PHP 5.4.11 they only validated as floats (using FILTER_VALIDATE_FLOAT).

When default is set to option, default's value is used if value is not validated.

更新日志

版本 说明
5.5.0 Added FILTER_VALIDATE_MAC
5.2.1 FILTER_VALIDATE_URL now implicitly uses FILTER_FLAG_SCHEME_REQUIRED and FILTER_FLAG_HOST_REQUIRED.

User Contributed Notes

luca at accomazzi dot net 04-May-2017 11:47
A word to the wise regarding floats.

$t = '312041.25 € instead of 896.70 €';
echo filter_var ($t, FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_FRACTION);

will return
312041.25896.70
which is likely not what you were expecting. In 2007 someone suggested it's not acceptable (see https://bugs.php.net/bug.php?id=40156&edit=2) but it was flagged "not a bug" because these kind of filters are only supposed to filter out illegal characters.
Of course if you were to use FILTER_VALIDATE_FLOAT it would just return that the input is not valid.
Marcus Stone 08-Mar-2017 09:40
Beware that 0 or 0.0 as a string literal is not considered to be a float.

//Prints 0.0 is not a float.
if (filter_var('0.0', FILTER_VALIDATE_FLOAT))
{
  echo '0.0 is a float';
}
else
{
    echo '0.0 is not a float';
}
kizge 30-Jun-2016 05:18
FILTER_VALIDATE_INT first casts its value to string which produces unexpected result for bool and float (https://bugs.php.net/bug.php?id=72490):

<?php

// Prints int(1).
var_dump(filter_var(true, FILTER_VALIDATE_INT));

// ...but this prints bool(false).
var_dump(filter_var(false, FILTER_VALIDATE_INT));

// --------

// Prints bool(false).
var_dump(filter_var(1.1, FILTER_VALIDATE_INT));

// ...but this prints int(0).
var_dump(filter_var(0.0, FILTER_VALIDATE_INT));

// ...but this again is bool(false).
var_dump(filter_var('0.0', FILTER_VALIDATE_INT));

// Also bool(false).
var_dump(filter_var('-0.0', FILTER_VALIDATE_INT));

?>

Live sample: https://3v4l.org/CZW0W

The docs are not clear on how exactly this casting affects the result for certain input values.
sebastian dot piskorski at gmail dot com 05-Jan-2016 09:48
FILTER_VALIDATE_EMAIL not only doesn't support whitespace folding and comments. It only checks Addr-spec part of email address. Otherwise it should mark such address as valid: 'Test Example <test@example.com>' because it is valid according to RFC 822.

Also address "test@localhost" should be valid. Which is mentioned in another note.

You can test it with this code:
<?php

$emails = array(
    'Test Example <test@example.com>',
    'test@localhost',
    'test@localhost.com'
);

foreach ($emails as $email) {
    echo (filter_var($email, FILTER_VALIDATE_EMAIL)) ?
        "[+] Email '$email' is valid\n" :
        "[-] Email '$email' is NOT valid\n";
}
?>

Output for PHP 5.3.21 - 7.0.1 :
[-] Email 'Test Example <test@example.com>' is NOT valid
[-] Email 'test@localhost' is NOT valid
[+] Email 'test@localhost.com' is valid
rsnell at usgs dot gov 26-Nov-2015 02:18
Note that if using FILTER_NULL_ON_FAILURE as a flag with the FILTER_VALIDATE_BOOLEAN id then NULL is no longer returned if the variable name is not set in the external variable array. It will instead return FALSE. In the description is says that when using the FILTER_NULL_ON_FAILURE flag that ' FALSE is returned only for "0", "false", "off", "no", and ""' an makes no mention of this additional state that can also return false. The behavior is mentioned on the filter_input documentation page under Return Values but that is not overly helpful if one is just looking here.

If FILTER_NULL_ON_FAILURE is not used then NULL is returned when the variable name is not set in the external variable array, TRUE is returned for "1", "true", "on" and "yes" and FALSE is returned for everything else.
william at crandell dot ws 20-Sep-2015 05:43
FILTER_VALIDATE_EMAIL on localhost emails will fail except when
used in conjunction with a subdomain such as www.localhost

FYI Sub domains generally are setup outside of the scope of php configurations.

Using the following code:

<?php
$email = "user@localhost";
echo "PHP Version: ".phpversion().'<br>';
if(filter_var($email, FILTER_VALIDATE_EMAIL)){
    echo $email.'<br>';
    var_dump(filter_var($email, FILTER_VALIDATE_EMAIL));
}else{
    var_dump(filter_var($email, FILTER_VALIDATE_EMAIL));
}
?>

Returns:
PHP Version: 5.5.29 //On MY server
bool(false)

While the following code:

<?php
$email = "user@www.localhost"; //Note the added subdomain www
echo "PHP Version: ".phpversion().'<br>';
if(filter_var($email, FILTER_VALIDATE_EMAIL)){
    echo $email.'<br>';
    var_dump(filter_var($email, FILTER_VALIDATE_EMAIL));
}else{
    var_dump(filter_var($email, FILTER_VALIDATE_EMAIL));
}
?>

Returns:
PHP Version: 5.5.29 //On MY server
user@www.localhost
string(18) "user@www.localhost"
Lech 06-Sep-2015 05:41
The description for FILTER_VALIDATE_URL seems incorrect/misleading. "Beware a valid URL may not specify the HTTP protocol" implies a valid URL cannot specify the HTTP protocol. I think "Beware a valid URL need not specify..." would be better.
Wrinkled Cheese 10-Jun-2015 12:33
When validating a URL, as documented, the protocol is not validated.  However, it is required to be present.

For example:

I don't expect a protocol to be present.  To validate expected input I have to add a "protocol" as a prefix, and return true or false, and further validate the input.

$r = filter_var(''this.doesnt.matter.so.why.is.it.required://'.$host, FILTER_VALIDATE_URL);
return ($r != '' && $r !== false) ? true : false;
Darth Killer 02-Jun-2015 05:54
Contrary to what documentation implies, the FILTER_NULL_ON_FAILURE seem to affect any validation filter, not just FILTER_VALIDATE_BOOLEAN. I've been using that since PHP 5.2, and as of PHP 5.6.8 it still works. I have no clue if it's a blug or if it is as intended, in which case the documentation needs to be fixed.

When the flag is used on a validation filter other than FILTER_VALIDATE_BOOLEAN, as expected the filter will return NULL instead of FALSE upon failure. This is quite useful when filtering a POST form with filter_input_array(), where you don't want to check what field is invalid and what field is missing. Just check if NULL is among the returned elements and you're done.

<?php
$definition = array(
   'login' => array(
      'filter' => FILTER_VALIDATE_STRING,
      'flags' => FILTER_NULL_ON_FAILURE
   ),
   'pwd' => FILTER_UNSAFE_RAW
);
$form_data = filter_input_array(INPUT_POST, $definition);
if(in_array(null, $form_data, true)) {
   // invalid form
} else {
   // valid form, let's proceed
}
?>

Of course, if you want more precise error messages that approach won't work. But it's still good to know, i believe.
Luuk 25-May-2015 07:23
@2:
$value = " 0 ";
$filtered = filter_var($value, FILTER_VALIDATE_INT);
if($filtered || $filtered === 0)
{
    // validated as an int
}

I think next code is better:

$value = "0";
if(filter_var($value, FILTER_VALIDATE_INT) !== false)
{
  .....
Anonymous 22-May-2015 05:02
FILTER_VALIDATE_FLOAT, decimal option mean decimal notation['.', ','].
maruerru at gmail dot com 27-Mar-2015 08:09
Often I see some code like the following:
$value = "12";
if( filter_var($value, FILTER_VALIDATE_INT) )
{
    // validated as an int
}

The above works as intended, except when $value is "0". In the above case it will be interpreted as FALSE.

For the correct behavior,  you have not only to check if it is equal (==) to false, but also identic (===) to FALSE:
$value = " 0 ";
if( filter_var($value, FILTER_VALIDATE_INT)  === FALSE )
{
    // validated as an int
}

I hope, I could help.
bryanwayb at gmail dot com 22-Mar-2015 01:18
It's good to remember that using filter_var is primarily for filtering input values when doing boolean logic comparisons. Take the following:

$value = "12";
if(filter_var($value, FILTER_VALIDATE_INT))
{
    // validated as an int
}

The above works as intended, except when $value = "0". In which case filter_var returns a 0, aka false when used as a boolean.

For the correct behavior, do a zero check.

$value = " 0 ";
$filtered = filter_var($value, FILTER_VALIDATE_INT);
if($filtered || $filtered === 0)
{
    // validated as an int
}
Bastien 24-Sep-2013 05:05
Rejection of so-called partial domains because of "missing" dot is not following section 2.3.5 of RFC 5321.

It says FQDNs are permitted, and com, org, or va are (well, may be) valids FQDNs. It depends on DNS, not on syntax.

Some TDLs (although few of them) have MX RRs, the for example "abuse@va" is correct.
rowan dot collins at gmail dot com 18-Mar-2013 05:22
Regarding "partial" addresses with no . in the domain part, a comment in the source code (in ext/filter/logical_filters.c) justifies this rejection thus:

     * The regex below is based on a regex by Michael Rushton.
     * However, it is not identical.  I changed it to only consider routeable
     * addresses as valid.  Michael's regex considers a@b a valid address
     * which conflicts with section 2.3.5 of RFC 5321 which states that:
     *
     *   Only resolvable, fully-qualified domain names (FQDNs) are permitted
     *   when domain names are used in SMTP.  In other words, names that can
     *   be resolved to MX RRs or address (i.e., A or AAAA) RRs (as discussed
     *   in Section 5) are permitted, as are CNAME RRs whose targets can be
     *   resolved, in turn, to MX or address RRs.  Local nicknames or
     *   unqualified names MUST NOT be used.
boy at relaxnow dot nl 19-Oct-2012 11:06
FILTER_VALIDATE_URL does not work with URNs, examples of valid URIs according to RFC3986 and if they are accepted by FILTER_VALIDATE_URL:

[PASS] ftp://ftp.is.co.za.example.org/rfc/rfc1808.txt
[PASS] gopher://spinaltap.micro.umn.example.edu/00/Weather/California/Los%20Angeles
[PASS] http://www.math.uio.no.example.net/faq/compression-faq/part1.html
[PASS] mailto:mduerst@ifi.unizh.example.gov
[PASS] news:comp.infosystems.www.servers.unix
[PASS] telnet://melvyl.ucop.example.edu/
[PASS] http://www.ietf.org/rfc/rfc2396.txt
[PASS] ldap://[2001:db8::7]/c=GB?objectClass?one
[PASS] mailto:John.Doe@example.com
[PASS] news:comp.infosystems.www.servers.unix
[FAIL] tel:+1-816-555-1212
[PASS] telnet://192.0.2.16:80/
[FAIL] urn:oasis:names:specification:docbook:dtd:xml:4.1.2
bee kay two at em ee dot com 06-May-2012 01:45
Notably missing is a way to validate text entry as printable,
printable multiline,
or printable and safe (tag free)

FILTER_VALIDATE_TEXT, which validates no special characters
perhaps with FILTER_FLAG_ALLOW_NEWLINE
and FILTER_FLAG_NOTAG to disallow tag starters
php at sethsyberg dot com 07-Apr-2011 10:00
When validating floats, you must use the Identical/Not identical operators for proper validation of zeros:

This will not work as expected:
<?php
$x = 0;
if (!filter_var($x, FILTER_VALIDATE_FLOAT)) {
    echo "$x is a valid float";
} else {
    echo "$x is NOT a valid float";
}
?>

This will work as expected:
<?php
$x = 0;
if (filter_var($x, FILTER_VALIDATE_FLOAT)!== false) {
    echo "$x is a valid float";
} else {
    echo "$x is NOT a valid float";
}
?>
php dot net at piskvor dot org 11-Feb-2011 05:57
FILTER_VALIDATE_EMAIL is discarding valid e-mail addresses containing IDN. Since there are real, live IDNs on the Internet, that means the filtered output is too strict, leading to false negatives.

Punycode-encoded IDN addresses pass the filter correctly; so before checking for validity, it is necessary to convert the e-mail address to punycode.
Clifton 05-Jan-2011 05:00
FILTER_VALIDATE_EMAIL does NOT allow incomplete e-mail addresses to be validated as mentioned by Tomas.

Using the following code:

<?php
$email = "clifton@example"; //Note the .com missing
echo "PHP Version: ".phpversion().'<br>';
if(filter_var($email, FILTER_VALIDATE_EMAIL)){
    echo $email.'<br>';
    var_dump(filter_var($email, FILTER_VALIDATE_EMAIL));
}else{
    var_dump(filter_var($email, FILTER_VALIDATE_EMAIL));   
}
?>

Returns:
PHP Version: 5.2.14 //On MY server, may be different depending on which version you have installed.
bool(false)

While the following code:

<?php
$email = "clifton@example.com"; //Note the .com added
echo "PHP Version: ".phpversion().'<br>';
if(filter_var($email, FILTER_VALIDATE_EMAIL)){
    echo $email.'<br>';
    var_dump(filter_var($email, FILTER_VALIDATE_EMAIL));
}else{
    var_dump(filter_var($email, FILTER_VALIDATE_EMAIL));   
}
?>

Returns:
PHP Version: 5.2.14 //On MY server, may be different depending on which version you have installed.
clifton@example.com
string(16) "clifton@example.com"

This feature is only available for PHP Versions (PHP 5 >= 5.2.0) according to documentation. So make sure your version is correct.

Cheers,
Clifton