Question

i know that empty is a bit faster then isset, but filter_has_var is a bit faster then isset (in php.net it written) so what is faster empty or filter_has_var ?

Answer 1

filter_has_var() might be useful if the superglobals have been purged for some reason, because it checks the original input data, not $_GET, $_POST, $_ETC.

For example:

$_GET["injected"] = 123;

var_dump( filter_has_var(INPUT_GET, "injected") );   // false

// or the other way round

While you can overwrite the variable, the filter extension accesses a separate copy. And INPUT_GET will not alias to the $_GET superglobal.

Apart from that another reason is to use it for unification. If you use filter_var extensively, than a ruleset would be more fond of using filter_has_var() over isset().

But don’t use one or the other because of any silly performance reasons.