PHP 5 Filters

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

PHP Filter Functions

Since PHP 5.2.0, the filter functions are enabled by default. You can use them directly in your code without any further installation.

Function	Description
filter_has_var()	Checks if variable of specified type exists
filter_id()	Returns the ID number of a specified filter
filter_input()	Gets a specific external variable by name and optionally filters it
filter_input_array()	Gets multiple external variables and optionally filters them
filter_list()	Returns an array of all supported filters
filter_var_array()	Gets multiple variables and optionally filters them
filter_var()	Filters a variable with a specified filter

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PHP Sanitize Filters

The sanitize filters are used to sanitize or clean the user inputs.

ID	Description
FILTER_SANITIZE_EMAIL	Remove all characters except letters, digits and !#$%&'*+-/=?^_`{|}~@.[]
FILTER_SANITIZE_ENCODED	URL-encode string, optionally strip or encode special characters.
FILTER_SANITIZE_MAGIC_QUOTES	Apply addslashes().
FILTER_SANITIZE_NUMBER_FLOAT	Remove all characters except digits, +- and optionally .,eE
FILTER_SANITIZE_NUMBER_INT	Remove all characters except digits, plus (+) and minus (-) sign.
FILTER_SANITIZE_SPECIAL_CHARS	HTML-escape '"<>& and characters with ASCII value less than 32, optionally strip or encode other special characters.
FILTER_SANITIZE_STRING	Strip tags, optionally strip or encode special characters.
FILTER_SANITIZE_STRIPPED	Alias of "string" filter.
FILTER_SANITIZE_URL	Remove all characters except letters, digits and $-_.+!*'(),{}|\\^~[]`<>#%";/?:@&=
FILTER_UNSAFE_RAW	Do nothing, optionally strip or encode special characters.

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Validate Filters

The sanitize filters are used to validate the user inputs.

ID	Description
FILTER_VALIDATE_BOOLEAN	Returns TRUE for "1", "true", "on" and "yes". Returns FALSE otherwise.
FILTER_VALIDATE_EMAIL	Validates value as e-mail.
FILTER_VALIDATE_FLOAT	Validates value as float.
FILTER_VALIDATE_INT	Validates value as integer optionally from the specified range.
FILTER_VALIDATE_IP	Validates value as IP address, optionally only IPv4 or IPv6 or not from private or reserved ranges.
FILTER_VALIDATE_REGEXP	Validates value against regexp, a Perl-compatible regular expression.
FILTER_VALIDATE_URL	Validates value as URL, optionally with required components.