filter_var()

filter_var() — Filters a variable with a specified filter.

Built-in function of PHP 8.5. The manual lists it as available in PHP 5 >= 5.2.0, PHP 7, PHP 8. This page is the reference card: signature, parameters and return value, plus the changelog and the example the manual provides.

What it does

Filter a variable using a FILTER_VALIDATE_* validation filters, a FILTER_SANITIZE_* sanitization filters, or a custom filter.

Signature

filter_var(mixed $value, int $filter = FILTER_DEFAULT, array|int $options = 0): mixed

Parameters

ParameterTypeWhat it takes
$valuemixedValue to filter.
$filterintThe filter to apply. Can be a validation filter by using one of the FILTER_VALIDATE_* constants, a sanitization filter by using one of the FILTER_SANITIZE_* or FILTER_UNSAFE_RAW, or a custom filter by using FILTER_CALLBACK.
$optionsarray|intEither an associative array of options, or a bitmask of filter flag constants FILTER_FLAG_*.

Return value

On success returns the filtered data. On failure false is returned, unless the FILTER_NULL_ON_FAILURE flag is used, in which case null is returned.

Example

A runnable snippet:

var_dump(filter_var('bob@example.com', FILTER_VALIDATE_EMAIL)); var_dump(filter_var('https://example.com', FILTER_VALIDATE_URL, FILTER_FLAG_PATH_REQUIRED));

Output:

string(15) "bob@example.com" bool(false)

See also

filter_var_array(), filter_input(), filter_input_array()

All PHP 8.5 built-in functions

Reference card built from the PHP manual page filter_var() (PHP documentation, CC BY 3.0). The page is generated from the manual, so the wording of the parameter and return value text follows php.net.