The special null value represents a variable with no value. null is the only possible value of type null. A variable is considered to be null if: Syntax There is only one value of type null, and that is the case-insensitive constant null . See also the functions is_null() and
unset(). Casting to nullWarning This feature has been DEPRECATED as of PHP 7.2.0, and REMOVED as of PHP 8.0.0. Relying on this feature is highly discouraged. Casting a variable to null using (unset) $var will not remove the variable or unset its
value. It will only return a null value. quickpick ¶ 11 years ago
Note: empty array is converted to null by non-strict equal '==' comparison. Use is_null() or '===' if there is possible of getting empty array.
$a = array();
$a == null <== return true $a === null < == return false is_null($a) <== return false
mattias at kregert dot se ¶ 1 year ago
Note that NULL works like a magic object with any attribute you can name, but they are all NULL:
foreach ( [ null, null ] as $person ) { $friends[] = [ 'Name'=>$person['name'], 'Phone'=>$person['cell'] ]; }
print_r($friends);
Array ( [0] => Array ( [Name] => [Phone] => )
[1] => Array ( [Name] => [Phone] => )
)
This means that: * NULL == NULL['foo']['bar']['whatever']
This can be slightly confusing if you accidentally slip a NULL into an array of other items.
Hayley
Watson ¶ 4 years ago
NULL is supposed to indicate the absence of a value, rather than being thought of as a value itself. It's the empty slot, it's the missing information, it's the unanswered question. It's not a jumped-up zero or empty set.
This is why a variable containing a NULL is considered to be unset: it doesn't have a value. Setting a variable to NULL is telling it to forget its value without providing a replacement value to remember instead. The variable remains so that you can give it a proper value to remember later; this is especially important when the variable is an array element or object property.
It's a bit of semantic awkwardness to speak of a "null value", but if a variable can exist without having a value, the language and implementation have to have something to represent that situation. Because someone will ask. If only to see if the slot has been filled.
Anonymous ¶ 4 years ago
Note: Non Strict Comparison '==' returns bool(true) for
null == 0 <-- returns true
Use Strict Comparison Instead
null === 0 <-- returns false
hydrogen at live dot in ¶ 1 year ago
I would like to add for clarification that:
$x=NULL;
--$x; // $x is still NULL. // Decrementing NULL, using Decrement Operator, gives NULL.
$x-=1; // $x is now int(-1). // This actually decrements value by 1.
On the other hand, Incrementation works simply as expected. Hope this helps :)
Mojo ¶ 1 year ago
Pay attention then using operator -- on NULL values:
$x = null; --$x; // $x is NULL $x--; // still NULL $x -= 1; // $x is -1
On other side for ++ everything works fine:
$x = null; ++$x; // $ix is 1
Does 0 count as empty PHP?
The following things are considered to be empty: "" (an empty string) 0 (0 as an integer) 0.0 (0 as a float)
Is 0 a null value?
The answer to that is rather simple: a NULL means that there is no value, we're looking at a blank/empty cell, and 0 means the value itself is 0. Considering there is a difference between NULL and 0, the way Tableau treats these two values therefore is different as well.
Is 0 True or false PHP?
Summary. A boolean value represents a truth value, which is either true or false . PHP evaluates the following values to false: false, 0, 0.0, empty string (“”), “0”, NULL, an empty array; other values are true .
Is 0 considered empty?
"0" is considered as no value or empty value.
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