Checking if a variable is null

Question

Possible Duplicate:
is_null($x) vs $x === null in PHP

In the following context !== null, !is_null() and isset() all produce the same result:

$foo = null;

function foo() {
    if ($this->foo !== null) {
        ...
    }
    if (!is_null($this->foo)) {
        ...
    }
    if (isset($this->foo)) {
        ...
    }
}

Which one is the quickest and which would you recommend in that context?

in PHP5 you can't use isset() for variable only for http request, post or get — Rob, Nov 15 '12 at 09:29
@Robuust What? of course you can use it for any variable. `$a = 5; if (isset($a)) { echo "a = {$a}"; }` — Corbin, Nov 15 '12 at 09:30
Regarding which is the quickest, [a comment on php.net](http://www.php.net/manual/en/function.is-null.php#83588) included benchmarks for each of the methods looping over 10M iterations. — Beardy, Nov 15 '12 at 09:30

score 2 · Accepted Answer · answered Nov 15 '12 at 09:27

If you're not sure that the variable exists, use isset.

Example:

$content = (isset($_POST['content'])) ? $_POST['content'] : null;

Otherwise, use strict comparison to null.

if ($content === null) { }

(Really, I'm just pushing my opinion on your with the strict comparison. I just think it looks better than is_null, and it's probably an extremely small bit faster.)

score 1 · Answer 2 · answered Nov 15 '12 at 09:27

Use isset only if the variable may not be set. I.e. if you do not know whether the variable exists at this point or not. Since you do know that it should exist at this point, don't use isset.

The difference between !== null and !is_null is negligible and mostly depends on your preference. Personally, I like !== null.

score 0 · Answer 3 · edited Nov 15 '12 at 09:45

0

if ($this->foo !== null) {
      //...
}

I prefer this condition.

edited Nov 15 '12 at 09:45

Adi

4,989
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answered Nov 15 '12 at 09:28

rOcKiNg RhO

611
1
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score 0 · Answer 4 · answered Nov 15 '12 at 09:57

0

According to me

  if($this->foo!=""){

//... }

this is the quickest one and produce the result quickly

answered Nov 15 '12 at 09:57

Rithu Psks

92
11

Checking if a variable is null

4 Answers4