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Filter Functions
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XLI. Filter Functions

Introduction

This extension serves for validating and filtering data coming usually 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:

Table 1. Existing filters

IDNameOptionsFlagsDescription
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"   Returns TRUE for "1", "true", "on" and "yes", FALSE for "0", "false", "off", "no", and "", NULL otherwise.
FILTER_VALIDATE_FLOAT"float"  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_SCHEME_REQUIRED, FILTER_FLAG_HOST_REQUIRED, 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 !#$%&'*+-/=?^_`{|}~@.[].
FILTER_SANITIZE_URL"url"   Remove all characters except letters, digits and $-_.+!*'(),{}|\\^~[]`<>#%";/?:@&=.
FILTER_SANITIZE_NUMBER_INT"number_int"   Remove all characters except digits and +-.
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 methodCall 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.

Table 2. Filter Configuration Options

NameDefaultChangeableChangelog
filter.defaultunsafe_rawPHP_INI_PERDIR 
filter.default_flags PHP_INI_PERDIR 
For further details and definitions of the PHP_INI_* constants, see the Appendix G.

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
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