Difference between !NULL and !IS_NULL?

[eldan88]

Hey I have a question? I just wanted to know the difference between both of them. Thanks

[Christian F.]

NULL is a value (or rather lack thereof), is_null () is a function (language construct, really) that checks a variable and returns true if it contains NULL. Read more about it in the PHP manual.

[eldan88]

NULL is a value (or rather lack thereof), is_null () is a function (language construct, really) that checks a variable and returns true if it contains NULL. Read more about it in the PHP manual.

 

Thank you very much for the helpful reply!

[salathe]

is_null () is a function (language construct, really)

 

The parenthetical remark is incorrect, is_null is a perfectly normal function and not a language construct.

[Christian F.]

Ah, you're right. Got it mixed up with isset (), sorry.

Thanks for the correction.

[The Little Guy]

it is faster to do:

 

if($value === null){
    // do something:
}

 

over

 

if(is_null($value)){
    // do something:
}

 

 

Iterations: 100000  (10 Runs)
#  | NULL     | rel %  | is_null() | rel %
----+----------+--------+-----------+--------
  1 |  0.02851 |  5.9 % |   0.48044 | 1685.4%
  2 |  0.03086 |  6.5 % |   0.47557 | 1541.2%
  3 |  0.02853 |  5.9 % |   0.48534 | 1700.9%
  4 |  0.02860 |  6.0 % |   0.47666 | 1666.6%
  5 |  0.02854 |  6.0 % |   0.47783 | 1674.3%
  6 |  0.02863 |  6.1 % |   0.47144 | 1646.7%
  7 |  0.02854 |  6.0 % |   0.47272 | 1656.2%
  8 |  0.02855 |  6.0 % |   0.47754 | 1672.6%
  9 |  0.02854 |  6.0 % |   0.47301 | 1657.5%
10 |  0.02853 |  6.0 % |   0.47380 | 1660.7%

[kicken]

it is faster to do

 

is_null involves a function call which is a relatively costly operation in PHP, that is why there is a speed difference.  I tend to use is_null anyway out of habit and I like the way it reads better when I skim code.  In practice it  generally makes little difference as you're probably not going to be calling it thousands of times.

 

Either method accomplishes the same task so use whichever you prefer.

 

[Christian F.]

Are those numbers microseconds, or nanoseconds? Either way, you don't want to teach newbies about micro-optimization like this. Point in case, even if the numbers are microseconds, you're still only saving 0.0000046th of a second for every check you do and you don't tend to do a whole lot of them.

 

The best course of action is to use whatever makes the code the easiest to read, as that'll help you save a lot more time (in development and maintenance) than it'll ever use in production.

 

[The Little Guy]

Here is the source:

http://hakre.wordpress.com/2011/03/29/php-is_null-vs-null/

 

That should also be time in seconds

[Jessica]

Here is the source:

http://hakre.wordpress.com/2011/03/29/php-is_null-vs-null/

 

That should also be time in seconds

 

The comment on there

"There is also a difference between NULL === $var and $var === NULL"

Annoys me. There is a difference? What is it? If you already figured out that there's a difference, post your work, man!

[The Little Guy]

Here is the source:

http://hakre.wordpress.com/2011/03/29/php-is_null-vs-null/

 

That should also be time in seconds

 

The comment on there

"There is also a difference between NULL === $var and $var === NULL"

Annoys me. There is a difference? What is it? If you already figured out that there's a difference, post your work, man!

 

 

I saw that too, so I had to try.... and... their wasn't a difference.

[premiso]

The comment on there

"There is also a difference between NULL === $var and $var === NULL"

What is it?

 

Obviously.... NULL has been switched with $var.

 

*premiso rollseyes

[Christian F.]

I've linked to this article before, explaining why micro-optimization generally isn't worth it. Especially not when you have no idea whether or not the code in question will actually be a bottle neck.

 

There's also more information in another article, about Premature Optimization, which I'm afraid your advice classifies as.

[Jessica]

Christian, OP asked if there was a difference. The Little Guy's post shows a difference. That's all. Chill.

[Christian F.]

I'm chilled, no worries. In fact, if I was any more relaxed I'd be sleeping. That's being 100% factual to boot.