Check if value isset and null

php null isset
Tatu Ulmanen picture Tatu Ulmanen · Sep 27, 2010 · Viewed 59.1k times · Source

I need to check if value is defined as anything, including null. isset treats null values as undefined and returns false. Take the following as an example:

$foo = null;

if(isset($foo)) // returns false
if(isset($bar)) // returns false
if(isset($foo) || is_null($foo)) // returns true
if(isset($bar) || is_null($bar)) // returns true, raises a notice

Note that $bar is undefined.

I need to find a condition that satisfies the following:

if(something($bar)) // returns false;
if(something($foo)) // returns true;

Any ideas?

Answer

Henrik Opel picture Henrik Opel · Sep 27, 2010

IIRC, you can use get_defined_vars() for this:

$foo = NULL;
$vars = get_defined_vars();
if (array_key_exists('bar', $vars)) {}; // Should evaluate to FALSE
if (array_key_exists('foo', $vars)) {}; // Should evaluate to TRUE

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