PHP Filter Introduction

This PHP filters is used to validate and filter data coming from insecure sources, like user input.

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Installation

The filter functions are part of the PHP core. There is no installation needed to use these functions.

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PHP Filter Functions

PHP: indicates the earliest version of PHP that supports the function.

Function	Description	PHP
filter_has_var()	Checks if a variable of a specified input type exist	5
filter_id()	Returns the ID number of a specified filter	5
filter_input()	Get input from outside the script and filter it	5
filter_input_array()	Get multiple inputs from outside the script and filters them	5
filter_list()	Returns an array of all supported filters	5
filter_var_array()	Get multiple variables and filter them	5
filter_var()	Get a variable and filter it	5

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PHP Filters

ID Name	Description
FILTER_CALLBACK	Call a user-defined function to filter data
FILTER_SANITIZE_STRING	Strip tags, optionally strip or encode special characters
FILTER_SANITIZE_STRIPPED	Alias of "string" filter
FILTER_SANITIZE_ENCODED	URL-encode string, optionally strip or encode special characters
FILTER_SANITIZE_SPECIAL_CHARS	HTML-escape '"<>& and characters with ASCII value less than 32
FILTER_SANITIZE_EMAIL	Remove all characters, except letters, digits and !#$%&'*+-/=?^_`{|}~@.[]
FILTER_SANITIZE_URL	Remove all characters, except letters, digits and $-_.+!*'(),{}|\\^~[]`<>#%";/?:@&=
FILTER_SANITIZE_NUMBER_INT	Remove all characters, except digits and +-
FILTER_SANITIZE_NUMBER_FLOAT	Remove all characters, except digits, +- and optionally .,eE
FILTER_SANITIZE_MAGIC_QUOTES	Apply addslashes()
FILTER_UNSAFE_RAW	Do nothing, optionally strip or encode special characters
FILTER_VALIDATE_INT	Validate value as integer, optionally from the specified range
FILTER_VALIDATE_BOOLEAN	Return TRUE for "1", "true", "on" and "yes", FALSE for "0", "false", "off", "no", and "", NULL otherwise
FILTER_VALIDATE_FLOAT	Validate value as float
FILTER_VALIDATE_REGEXP	Validate value against regexp, a Perl-compatible regular expression
FILTER_VALIDATE_URL	Validate value as URL, optionally with required components
FILTER_VALIDATE_EMAIL	Validate value as e-mail
FILTER_VALIDATE_IP	Validate value as IP address, optionally only IPv4 or IPv6 or not from private or reserved ranges