PHP Filter Functions

PHP Filter Introduction

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

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

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