Introduction

This extension serves to validate and filter data coming from some insecure source, such as user input.

The following filters currently exist; be sure to read the Filter Constants section for information that describes the behavior of each constant:

Existing filters

ID	Name	Options	Flags	Description
FILTER_VALIDATE_INT	"int"	min_range , max_range	FILTER_FLAG_ALLOW_OCTAL, FILTER_FLAG_ALLOW_HEX	Validates value as integer, optionally from the specified range.
FILTER_VALIDATE_BOOLEAN	"boolean"		FILTER_NULL_ON_FAILURE	Returns TRUE for "1", "true", "on" and "yes". Returns FALSE otherwise. If FILTER_NULL_ON_FAILURE is set, FALSE is returned only for "0", "false", "off", "no", and "", and NULL is returned for all non-boolean values.
FILTER_VALIDATE_FLOAT	"float"	decimal	FILTER_FLAG_ALLOW_THOUSAND	Validates value as float.
FILTER_VALIDATE_REGEXP	"validate_regexp"	regexp		Validates value against regexp , a Perl-compatible regular expression.
FILTER_VALIDATE_URL	"validate_url"		FILTER_FLAG_PATH_REQUIRED, FILTER_FLAG_QUERY_REQUIRED	Validates value as URL, optionally with required components.
FILTER_VALIDATE_EMAIL	"validate_email"			Validates value as e-mail.
FILTER_VALIDATE_IP	"validate_ip"		FILTER_FLAG_IPV4, FILTER_FLAG_IPV6, FILTER_FLAG_NO_PRIV_RANGE, FILTER_FLAG_NO_RES_RANGE	Validates value as IP address, optionally only IPv4 or IPv6 or not from private or reserved ranges.
FILTER_SANITIZE_STRING	"string"		FILTER_FLAG_NO_ENCODE_QUOTES, FILTER_FLAG_STRIP_LOW, FILTER_FLAG_STRIP_HIGH, FILTER_FLAG_ENCODE_LOW, FILTER_FLAG_ENCODE_HIGH, FILTER_FLAG_ENCODE_AMP	Strip tags, optionally strip or encode special characters.
FILTER_SANITIZE_STRIPPED	"stripped"			Alias of "string" filter.
FILTER_SANITIZE_ENCODED	"encoded"		FILTER_FLAG_STRIP_LOW, FILTER_FLAG_STRIP_HIGH, FILTER_FLAG_ENCODE_LOW, FILTER_FLAG_ENCODE_HIGH	URL-encode string, optionally strip or encode special characters.
FILTER_SANITIZE_SPECIAL_CHARS	"special_chars"		FILTER_FLAG_STRIP_LOW, FILTER_FLAG_STRIP_HIGH, FILTER_FLAG_ENCODE_HIGH	HTML-escape '"<>& and characters with ASCII value less than 32, optionally strip or encode other special characters.
FILTER_UNSAFE_RAW	"unsafe_raw"		FILTER_FLAG_STRIP_LOW, FILTER_FLAG_STRIP_HIGH, FILTER_FLAG_ENCODE_LOW, FILTER_FLAG_ENCODE_HIGH, FILTER_FLAG_ENCODE_AMP	Do nothing, optionally strip or encode special characters.
FILTER_SANITIZE_EMAIL	"email"			Remove all characters except letters, digits and !#$%&'*+-/=?^_`{|}~@.[].
FILTER_SANITIZE_URL	"url"			Remove all characters except letters, digits and $-_.+!*'(),{}|\\^~[]`<>#%";/?:@&=.
FILTER_SANITIZE_NUMBER_INT	"number_int"			Remove all characters except digits, plus and minus sign.
FILTER_SANITIZE_NUMBER_FLOAT	"number_float"		FILTER_FLAG_ALLOW_FRACTION, FILTER_FLAG_ALLOW_THOUSAND, FILTER_FLAG_ALLOW_SCIENTIFIC	Remove all characters except digits, +- and optionally .,eE.
FILTER_SANITIZE_MAGIC_QUOTES	"magic_quotes"			Apply addslashes().
FILTER_CALLBACK	"callback"	callback function or method		Call user-defined function to filter data.