PHP Filter Functions

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