What is the fastest is_null ($ y) or $ y == null?

Expression Security

The question you really should ask is " Which is safer to use? ". For example, the following expressions:

"oi" == null    => false
""   == null    => true
0    == null    => true
null == null    => true

is_null("oi")   => false
is_null("")     => false
is_null(0)      => false
is_null(null)   => true

"oi" === null   => false
""   === null   => false
0    === null   => false
null === null   => true

Optimization

The difference between === and is_null is pretty much irrelevant, unless you have about two million such expressions in a script to require meaningful optimization.

One of the comments in the PHP documentation says the following (in free translation) :

  

Micro optimization is not worth it.

     

You had to do it ten million times to notice a difference, just over 2 seconds

     

$a===NULL; lasted: 1.2424390316s

     

is_null($a); lasted: 3.70693397522s

     

Difference = 2,46449494362s

     

Difference / 10,000,000 = 0.000000246449494362ns

     

The execution time between === NULL and is_null is less than 250 nanoseconds . Go optimize something worthwhile.

Note: I did some tests and the various results did not exceed 100 nanoseconds, and the mean difference was between 20 ~ 50 nanoseconds.

Conclusion

If you really want to optimize and have security in your code, give preference to triple-operator comparison:

$y === null

But it's not worth scraping code to optimize these expressions (unless you look for the simple == operator). Because the difference is so insignificant, that time would be better invested if you were cleaning / improving the code or studying.

More on logical expressions: link

More details on logical operators: link

It all depends on what you want to check, you should not just look at performance. For example:

<?php

$str1 = "";
$str2 = null;
$str3 = 0;

var_dump(is_null($str1)); // retorna false
var_dump(is_null($str2)); // retorna true
var_dump(is_null($str3)); // retorna false

var_dump($str1 == null); // retorna true
var_dump($str2 == null); // retorna true
var_dump($str3 == null); // retorna true

?>

Your question is creepy because the result is never the same for:

is_null($y) ou $y == null

To compare you should do so over:

is_null($y) ou $y === null

Here the results will be similar. It is important to mention that there are situations where the applicability of the === operator is impossible. In cases that need to be used in callbacks only is_null can be used.

In a direct answer to the question regarding performance: The difference is not relevant.

More: Both are different approaches to the same problem.

Because ...

Opinion: I apply according to the situation, but I would always choose $ y === null because it is a base operator and for that reason nuclear ... so PHP tends to resolve with less effort certainly.     

There is no difference between is_null and === null . It unifies difference and that is_null is a function and consequently,

1 ° Calling the function slows down, but this is relatively unimportant.

2 ° Because it is a function you can use it as a callback example:

  array_map('is_null', $array);

In the php documentation there is a benchmarking test with 10 million iterations that ends up as follows, comparing a variable with an operator is much faster, so do not use is_null unless you need a callback .

Php - Manual

$ y == null .

In terms of performance, the difference is not so relevant, but if used frequently, it's really worth it, just use it.