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Filter Functions

Introduction

This extension serves to validate and filter data coming from some insecure source, such as user input.

The following filters currently exist; be sure to read the Filter Constants section for information that describes the behavior of each constant:

Existing filters
ID Name Options Flags Description
FILTER_VALIDATE_INT "int" min_range , max_range FILTER_FLAG_ALLOW_OCTAL, FILTER_FLAG_ALLOW_HEX Validates value as integer, optionally from the specified range.
FILTER_VALIDATE_BOOLEAN "boolean"   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_FLOAT "float" decimal FILTER_FLAG_ALLOW_THOUSAND Validates value as float.
FILTER_VALIDATE_REGEXP "validate_regexp" regexp   Validates value against regexp , a Perl-compatible regular expression.
FILTER_VALIDATE_URL "validate_url"   FILTER_FLAG_PATH_REQUIRED, FILTER_FLAG_QUERY_REQUIRED Validates value as URL, optionally with required components.
FILTER_VALIDATE_EMAIL "validate_email"     Validates value as e-mail.
FILTER_VALIDATE_IP "validate_ip"   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_SANITIZE_STRING "string"   FILTER_FLAG_NO_ENCODE_QUOTES, FILTER_FLAG_STRIP_LOW, FILTER_FLAG_STRIP_HIGH, FILTER_FLAG_ENCODE_LOW, FILTER_FLAG_ENCODE_HIGH, FILTER_FLAG_ENCODE_AMP Strip tags, optionally strip or encode special characters.
FILTER_SANITIZE_STRIPPED "stripped"     Alias of "string" filter.
FILTER_SANITIZE_ENCODED "encoded"   FILTER_FLAG_STRIP_LOW, FILTER_FLAG_STRIP_HIGH, FILTER_FLAG_ENCODE_LOW, FILTER_FLAG_ENCODE_HIGH URL-encode string, optionally strip or encode special characters.
FILTER_SANITIZE_SPECIAL_CHARS "special_chars"   FILTER_FLAG_STRIP_LOW, FILTER_FLAG_STRIP_HIGH, FILTER_FLAG_ENCODE_HIGH HTML-escape '"<>& and characters with ASCII value less than 32, optionally strip or encode other special characters.
FILTER_UNSAFE_RAW "unsafe_raw"   FILTER_FLAG_STRIP_LOW, FILTER_FLAG_STRIP_HIGH, FILTER_FLAG_ENCODE_LOW, FILTER_FLAG_ENCODE_HIGH, FILTER_FLAG_ENCODE_AMP Do nothing, optionally strip or encode special characters.
FILTER_SANITIZE_EMAIL "email"     Remove all characters except letters, digits and !#$%&'*+-/=?^_`{|}[email protected][].
FILTER_SANITIZE_URL "url"     Remove all characters except letters, digits and $-_.+!*'(),{}|\\^~[]`<>#%";/?:@&=.
FILTER_SANITIZE_NUMBER_INT "number_int"     Remove all characters except digits, plus and minus sign.
FILTER_SANITIZE_NUMBER_FLOAT "number_float"   FILTER_FLAG_ALLOW_FRACTION, FILTER_FLAG_ALLOW_THOUSAND, FILTER_FLAG_ALLOW_SCIENTIFIC Remove all characters except digits, +- and optionally .,eE.
FILTER_SANITIZE_MAGIC_QUOTES "magic_quotes"     Apply addslashes().
FILTER_CALLBACK "callback" callback function or method   Call user-defined function to filter data.

Requirements

No external libraries are needed to build this extension.

Installation

A short installation note: just type

$ pecl install filter
  
in your console.

Runtime Configuration

The behaviour of these functions is affected by settings in php.ini.

Filter Configuration Options
Name Default Changeable Changelog
filter.default "unsafe_raw" PHP_INI_PERDIR PHP_INI_ALL in filter <= 0.9.4. Available since PHP 5.2.0.
filter.default_flags NULL PHP_INI_PERDIR PHP_INI_ALL in filter <= 0.9.4. Available since PHP 5.2.0.
For further details and definitions of the PHP_INI_* constants, see the php.ini directives.

Here's a short explanation of the configuration directives.

filter.default string

Filter all $_GET, $_POST, $_COOKIE and $_REQUEST data by this filter. Original data can be accessed through filter_input().

Accepts the name of the filter you like to use by default. See the existing filter list for the list of the filter names.

filter.default_flags integer

Default flags

Resource Types

This extension has no resource types defined.

Predefined Constants

The constants below are defined by this extension, and will only be available when the extension has either been compiled into PHP or dynamically loaded at runtime.

INPUT_POST (integer)
POST variables.
INPUT_GET (integer)
GET variables.
INPUT_COOKIE (integer)
COOKIE variables.
INPUT_ENV (integer)
ENV variables.
INPUT_SERVER (integer)
SERVER variables.
INPUT_SESSION (integer)
SESSION variables. (not implemented yet)
INPUT_REQUEST (integer)
REQUEST variables. (not implemented yet)
FILTER_FLAG_NONE (integer)
No flags.
FILTER_REQUIRE_SCALAR (integer)
Flag used to require scalar as input
FILTER_REQUIRE_ARRAY (integer)
Require an array as input.
FILTER_FORCE_ARRAY (integer)
Always returns an array.
FILTER_NULL_ON_FAILURE (integer)
Use NULL instead of FALSE on failure.
FILTER_VALIDATE_INT (integer)
ID of "int" filter.
FILTER_VALIDATE_BOOLEAN (integer)
ID of "boolean" filter.
FILTER_VALIDATE_FLOAT (integer)
ID of "float" filter.
FILTER_VALIDATE_REGEXP (integer)
ID of "validate_regexp" filter.
FILTER_VALIDATE_URL (integer)
ID of "validate_url" filter.
FILTER_VALIDATE_EMAIL (integer)
ID of "validate_email" filter.
FILTER_VALIDATE_IP (integer)
ID of "validate_ip" filter.
FILTER_DEFAULT (integer)
ID of default ("string") filter.
FILTER_UNSAFE_RAW (integer)
ID of "unsafe_raw" filter.
FILTER_SANITIZE_STRING (integer)
ID of "string" filter.
FILTER_SANITIZE_STRIPPED (integer)
ID of "stripped" filter.
FILTER_SANITIZE_ENCODED (integer)
ID of "encoded" filter.
FILTER_SANITIZE_SPECIAL_CHARS (integer)
ID of "special_chars" filter.
FILTER_SANITIZE_EMAIL (integer)
ID of "email" filter.
FILTER_SANITIZE_URL (integer)
ID of "url" filter.
FILTER_SANITIZE_NUMBER_INT (integer)
ID of "number_int" filter.
FILTER_SANITIZE_NUMBER_FLOAT (integer)
ID of "number_float" filter.
FILTER_SANITIZE_MAGIC_QUOTES (integer)
ID of "magic_quotes" filter.
FILTER_CALLBACK (integer)
ID of "callback" filter.
FILTER_FLAG_ALLOW_OCTAL (integer)
Allow octal notation (0[0-7]+) in "int" filter.
FILTER_FLAG_ALLOW_HEX (integer)
Allow hex notation (0x[0-9a-fA-F]+) in "int" filter.
FILTER_FLAG_STRIP_LOW (integer)
Strip characters with ASCII value less than 32.
FILTER_FLAG_STRIP_HIGH (integer)
Strip characters with ASCII value greater than 127.
FILTER_FLAG_ENCODE_LOW (integer)
Encode characters with ASCII value less than 32.
FILTER_FLAG_ENCODE_HIGH (integer)
Encode characters with ASCII value greater than 127.
FILTER_FLAG_ENCODE_AMP (integer)
Encode &.
FILTER_FLAG_NO_ENCODE_QUOTES (integer)
Don't encode ' and ".
FILTER_FLAG_EMPTY_STRING_NULL (integer)
(No use for now.)
FILTER_FLAG_ALLOW_FRACTION (integer)
Allow fractional part in "number_float" filter.
FILTER_FLAG_ALLOW_THOUSAND (integer)
Allow thousand separator (,) in "number_float" filter.
FILTER_FLAG_ALLOW_SCIENTIFIC (integer)
Allow scientific notation (e, E) in "number_float" filter.
FILTER_FLAG_SCHEME_REQUIRED (integer)
Require scheme in "validate_url" filter.
FILTER_FLAG_HOST_REQUIRED (integer)
Require host in "validate_url" filter.
FILTER_FLAG_PATH_REQUIRED (integer)
Require path in "validate_url" filter.
FILTER_FLAG_QUERY_REQUIRED (integer)
Require query in "validate_url" filter.
FILTER_FLAG_IPV4 (integer)
Allow only IPv4 address in "validate_ip" filter.
FILTER_FLAG_IPV6 (integer)
Allow only IPv6 address in "validate_ip" filter.
FILTER_FLAG_NO_RES_RANGE (integer)
Deny reserved addresses in "validate_ip" filter.
FILTER_FLAG_NO_PRIV_RANGE (integer)
Deny private addresses in "validate_ip" filter.

Table of Contents

  • filter_has_var — Checks if variable of specified type exists
  • filter_id — Returns the filter ID belonging to a named filter
  • filter_input_array — Gets multiple variables from outside PHP and optionally filters them
  • filter_input — Gets variable from outside PHP and optionally filters it
  • filter_list — Returns a list of all supported filters
  • filter_var_array — Gets multiple variables and optionally filters them
  • filter_var — Filters a variable with a specified filter