Curriculum

PHP Basic

PHP Intro

0/1

PHP Install

0/1

PHP Syntax

0/1

PHP Comments

0/2

PHP Variables

0/4

PHP echo / print

0/3

PHP Data Types

0/7

PHP Strings

0/5

PHP Numbers

0/2

PHP Casting

0/1

PHP Math

0/1

PHP Constants

0/1

PHP Magic Constants

0/1

PHP Operators

0/1

PHP if...Else...Elseif

0/5

PHP switch

0/1

PHP Loops

0/7

PHP Functions

0/6

PHP Arrays

0/11

PHP Superglobals

0/7

PHP RegEx

0/1

PHP Form

0/9

PHP Advanced

0/15

PHP OOP

0/14

MySQL Database

0/14

PHP XML

0/5

PHP Reference

0/276

Text lesson

PHP Filter

PHP Filter Introduction

PHP filters are used to validate and sanitize data from insecure sources, such as user input.

Installation

Since PHP 5.2.0, filter functions are enabled by default and require no additional installation to use.

Runtime Configurations

The behavior of these functions is influenced by settings in the php.ini file.

Name	Description	Default	Changeable
filter.default	Apply a filter to all $_GET, $_POST, $_COOKIE, $_REQUEST, and $_SERVER data. You can specify the default filter name to use. Refer to the filter list for available filter names.	“unsafe_raw”	PHP_INI_PERDIR
filter.default_flags	Default flags applied when the default filter is set. By default, it is set to FILTER_FLAG_NO_ENCODE_QUOTES for backward compatibility.	NULL	PHP_INI_PERDIR

PHP Filter Functions

Function	Description
filter_has_var()	Checks if a variable of a specified input type exists.
filter_id()	Returns the ID of a specified filter name.
filter_input()	Retrieves an external variable (e.g., from form input) and optionally applies a filter to it.
filter_input_array()	Retrieves external variables (e.g., from form input) and optionally applies filters to them.
filter_list()	Provides a list of all supported filter names.
filter_var()	Applies a specified filter to a variable.
filter_var_array()	Retrieves multiple variables and applies filters to them.

PHP Predefined Filter Constants

Constant	Description
INPUT_POST	POST variables
INPUT_GET	GET variables
INPUT_COOKIE	COOKIE variables
INPUT_ENV	ENV variables
INPUT_SERVER	SERVER variables
FILTER_DEFAULT	Does nothing by default but can optionally strip or encode special characters. Equivalent to FILTER_UNSAFE_RAW.
FILTER_FLAG_NONE	Disallows flags.
FILTER_FLAG_ALLOW_OCTAL	Applicable only to inputs that start with a zero (`0`) as octal numbers, allowing only the digits 0-7 to follow.
FILTER_FLAG_ALLOW_HEX	Applicable only to inputs that begin with `0x` or `0X` as hexadecimal numbers, allowing only the characters a-f, A-F, and 0-9 to follow.
FILTER_FLAG_STRIP_LOW	Strip characters with ASCII values less than 32.
FILTER_FLAG_STRIP_HIGH	Strip characters with ASCII values greater than 127.
FILTER_FLAG_ENCODE_LOW	Encode characters with ASCII values less than 32.
FILTER_FLAG_ENCODE_HIGH	Encode characters with ASCII values exceeding 127.
FILTER_FLAG_ENCODE_AMP	Encode &
FILTER_FLAG_NO_ENCODE_QUOTES	Do not encode ‘ and “
FILTER_FLAG_EMPTY_STRING_NULL	Not in use
FILTER_FLAG_ALLOW_FRACTION	Allows a period (`.`) as a decimal separator in numbers.
FILTER_FLAG_ALLOW_THOUSAND	Allows a comma (`,`) as a thousands separator in numbers.
FILTER_FLAG_ALLOW_SCIENTIFIC	Allows the use of `e` or `E` for scientific notation in numbers.
FILTER_FLAG_PATH_REQUIRED	The URL must include a path component.
FILTER_FLAG_QUERY_REQUIRED	The URL must include a query string.
FILTER_FLAG_IPV4	Allows the IP address to be in IPv4 format.
FILTER_FLAG_IPV6	Allows the IP address to be in IPv6 format.
FILTER_FLAG_NO_RES_RANGE	Fails validation for reserved IPv4 ranges such as 0.0.0.0/8, 169.254.0.0/16, 127.0.0.0/8, and 240.0.0.0/4, as well as for reserved IPv6 ranges including ::1/128, ::/128, ::ffff:0:0/96, and fe80::/10.
FILTER_FLAG_NO_PRIV_RANGE	Fails validation for private IPv4 ranges like 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16, as well as for IPv6 addresses beginning with FD or FC.
FILTER_FLAG_EMAIL_UNICODE	Allows the local part of the email address to include Unicode characters.
FILTER_REQUIRE_SCALAR	The value must be a scalar.
FILTER_REQUIRE_ARRAY	The value must be an array.
FILTER_FORCE_ARRAY	Treats a scalar value as an array with the scalar value as its only element.
FILTER_NULL_ON_FAILURE	Returns NULL on failure for unrecognized boolean values.
FILTER_VALIDATE_BOOLEAN	Validates a boolean value.
FILTER_VALIDATE_EMAIL	Validates the value as a valid email address.
FILTER_VALIDATE_FLOAT	Validates the value as a float.
FILTER_VALIDATE_INT	Validates the value as an integer.
FILTER_VALIDATE_IP	Validates the value as an IP address.
FILTER_VALIDATE_MAC	Validates the value as a MAC address.
FILTER_VALIDATE_REGEXP	Validates the value against a regular expression.
FILTER_VALIDATE_URL	Validates the value as a URL.
FILTER_SANITIZE_ADD_SLASHES	Introduced as a replacement for FILTER_SANITIZE_MAGIC_QUOTES.
FILTER_SANITIZE_EMAIL	Removes all invalid characters from an email address.
FILTER_SANITIZE_ENCODED	Removes or encodes special characters.
FILTER_SANITIZE_MAGIC_QUOTES	Applies addslashes(). Deprecated as of PHP 7.3.0 and removed in PHP 8.0.0.
FILTER_SANITIZE_NUMBER_FLOAT	Removes all characters except digits, `+`, `-`, and optionally `.` and `eE`.
FILTER_SANITIZE_NUMBER_INT	Removes all characters except digits and the `+` and `-` signs.
FILTER_SANITIZE_SPECIAL_CHARS	Removes special characters.
FILTER_SANITIZE_STRING	Removes tags and special characters from a string; deprecated as of PHP 8.1.0.
FILTER_SANITIZE_STRIPPED	An alias for FILTER_SANITIZE_STRING, deprecated as of PHP 8.1.0.
FILTER_SANITIZE_URL	Removes all invalid characters from a URL.
FILTER_UNSAFE_RAW	Do nothing, with an option to strip or encode special characters.
FILTER_CALLBACK	Invoke a user-defined function to filter data.