PHP Filter Functions

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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 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

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_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

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