check if a variable is defined (null or not)

Question

I would like to test if a variable exists This variable can be set to null.

Is there a function can test that?

isset() returns false if the variable exists but defined to null. I can't use is_null() if my $var is not defined.

Edit: my var is an object property so I did this:

property_exists($pData, $key)

and that works

Thx

Nope! There is no built-in function aimed for that specific requirement. — felipsmartins, Jan 11 '18 at 16:04
There is no built-in function to check is variable exists in PHP. [`isset()`](http://php.net/manual/en/function.isset.php) is proper way to check is variable is set or exists. There is also [`defined()`](http://php.net/manual/en/function.defined.php) function which work only for contasts. See also this [question](https://stackoverflow.com/questions/30191521/php-check-if-variable-is-undefined) — Andriy Sushchyk, Jan 11 '18 at 16:06
`isset(get_defined_vars()['var'])` will work in global scope or in method function scope. — AbraCadaver, Jan 11 '18 at 16:23
my var is an object property so I did this: `property_exists($pData, $key)` and it works — Paul, Jan 11 '18 at 16:32

score 1 · Answer 1 · answered Jan 11 '18 at 16:08

I don't think you can - and you probably shouldn't. However, if you aren't using methods you can check the global scope:

$x = null;

var_dump(array_key_exists('x', $GLOBALS)); # true
var_dump(array_key_exists('y', $GLOBALS)); # false

1 Answers1