Possible Duplicate:
Check if value isset and null
If I have $v = NULL; how can I check that $v is exists and it's NULL?
isset($v) => false //because of NULL, but $v exists
You can’t, null is equivalent to a non-existing variable:
A variable is considered to be null if:
- it has been assigned the constant
NULL.- it has not been set to any value yet.
- it has been
unset().
Only for arrays you can check whether a key exists although its value is null using array_key_exists.
Try is_null($v).
If you would like to put it all together to test existence and a null value
<?php
if(!is_null($v)){
// do something
}
?>
You should be careful using isset on variables that can be null. It's a good way to set yourself up for bugs and problems in the future.
What you could do for now is to use is_null as an additional test.