Bug #68761 [ReO->Csd]: filter_var(null) returns false with FILTER_NULL_ON_FAILURE

Edit report at https://bugs.php.net/bug.php?id=68761&edit=1 ID: 68761 Updated by: cmb@php.net Reported by: tonyli dot lives at gmail dot com Summary: filter_var(null) returns false with FILTER_NULL_ON_FAILURE -Status: Re-Opened +Status: Closed Type: Bug Package: Filter related Operating System: Ubuntu 12.04 PHP Version: 5.5.20 Assigned To: cmb Block user comment: N Private report: N New Comment: > […], since the documentation could be clarified regarding the > string conversion. Oh, that is already documented[1]: | Note that scalar values are converted to string internally | before they are filtered. [1] <https://www.php.net/manual/en/function.filter-var.php> Previous Comments: ------------------------------------------------------------------------ [2020-07-29 15:11:10] cmb@php.net > Why is false returned for null? Because the filter_*() functions are meant to operate on strings, so values of other types are converted to string first; NULL is converted to an empty string, and an empty string is supposed to return FALSE with FILTER_NULL_ON_FAILURE. Re-opening, since the documentation could be clarified regarding the string conversion. ------------------------------------------------------------------------ [2020-07-29 14:09:32] rihards dot sceredins at creative dot gs Hey, It seems that the author of this bug report mixed "expected result" with "actual result". I just tried this on PHP 7.4.8 and output of the test script mentioned above is: bool(false) bool(false) bool(true) NULL Why is false returned for null? ------------------------------------------------------------------------ [2016-09-26 14:47:10] cmb@php.net That issue has been resolved as of PHP 5.4.8, see <https://3v4l.org/cBDRY>. ------------------------------------------------------------------------ [2015-01-15 10:53:52] ppasindud at gmail dot com Works correctly in php-src master ------------------------------------------------------------------------ [2015-01-06 22:17:55] tonyli dot lives at gmail dot com Description: ------------ Even with the flag on, trying to filter null returns false when it should be still null (as null is not a boolean). As per the documentation: 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. Similar to: https://bugs.php.net/bug.php?id=67167 Test script: --------------- var_dump(filter_var(null, FILTER_VALIDATE_BOOLEAN, FILTER_NULL_ON_FAILURE)); var_dump(filter_var(false, FILTER_VALIDATE_BOOLEAN, FILTER_NULL_ON_FAILURE)); var_dump(filter_var(true, FILTER_VALIDATE_BOOLEAN, FILTER_NULL_ON_FAILURE)); var_dump(filter_var('test', FILTER_VALIDATE_BOOLEAN, FILTER_NULL_ON_FAILURE)); Expected result: ---------------- bool(false) bool(false) bool(true) NULL Actual result: -------------- NULL bool(false) bool(true) NULL ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=68761&edit=1