Correct way to check (with PHP) a variable before looping through?

Question

Before looping through a variable (supposed to be an array) I would make the following test:

if(
        !empty($arrJobs)    &&
        is_array($arrJobs)  &&
        count($arrJobs)
){
foreach ($arrJobs as $item) {
  //loop tasks
}
}

I've seen also using if(sizeof($arrJobs)>0) but in case $arrJobs isa integer (I can't trust the input) it would be through and I will try looping through a integer...weird.

Is there a more concise and comprehensive way to perform this test before looping through the array?

Possible duplicate of [How to check if variable is array?... or something array-like](http://stackoverflow.com/questions/15603952/how-to-check-if-variable-is-array-or-something-array-like) — Naruto, Sep 23 '16 at 08:56

Emz · Answer 1 · 2016-09-23T09:06:49.353

1

It is IMPORTANT to check if you're looping an ARRAY to FOREACH or else PHP will give you errors ... FOREACH expects parameter to be ARRAY..

You can use IS_ARRAY .. I believe that would be enough.

But checking it if empty would be VERY GOOD Practice... I'm using COUNT() to check if an ARRAY is empty.

edited Sep 23 '16 at 09:06

answered Sep 23 '16 at 09:00

Emz

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INTERESTING answer – Farkie Sep 23 '16 at 09:02

DonCallisto · Answer 2 · 2016-09-23T09:11:55.660

0

You don't need to check anything but is_array: if it's empty, PHP simply won't loop.

Moreover a suggestion: if those if had sense (not that case, but is helpful for this explanation) you should split with "early exit" (as coding style because it improves readability)

if (empty($arrJobs)) {
 return;
}

if (!is_array($arrJobs)) {
 return;
}

if (count($arrJobs)) {
 return;
}

edited Sep 23 '16 at 09:11

answered Sep 23 '16 at 08:57

DonCallisto

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do they have sense if you need to do something (or report something ) if array is empty? don't they? – koalaok Sep 23 '16 at 08:59
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@DonCallisto PHP has short-circuit condition evaluation, so after evaluation of first condition as false it skips other comparsions, so this "early-exit" is useless, just more code. – Jan Holas Sep 23 '16 at 09:01
is_array seems to have some sense... if the variable has another type: Invalid argument supplied for foreach() – koalaok Sep 23 '16 at 09:01
@JanHolas yes I *perfectly* know this ... Mine suggestion was about readability – DonCallisto Sep 23 '16 at 09:02
on the other hand... even if PHP let you play dirty, it doesn't mean you shouldn't worry about writing code in a solid flavour.(if it doesn't affect performance, and not adding garbage lines) IMHO – koalaok Sep 23 '16 at 09:03
1

This "early exit suggestion" certainly does _not_ raise readability! – arkascha Sep 23 '16 at 09:04
@DonCallisto I don't think it's more readble, but it's probably just matter of style and opinion. It might be usefull if you want to display different error message for each condition. – Jan Holas Sep 23 '16 at 09:04
@koalaok no one let play you dirty: if something is array, so it's traversable, and it's empty, you should not check it *on purpose*. fullstop. – DonCallisto Sep 23 '16 at 09:04
@KOALAOK.. check my answer below – Emz Sep 23 '16 at 09:04
@arkascha what if you have, let's say, ten `&&` condition? – DonCallisto Sep 23 '16 at 09:06
@victor yep I agree with you. Upvoted and going to accept it. It would be great if php had a function that would check both is_array && !empty at the same time. – koalaok Sep 23 '16 at 09:06
@Koalaok ... well you can create a function yourself... that would return a boolean... so you can just call that function in your if-statement .. and you can use it to your other projects.. .. make sense? :-) – Emz Sep 23 '16 at 09:08
@arkascha I think the right way for readability stays in the middle. – koalaok Sep 23 '16 at 09:10
@victor makes sense. But it's annoying to have to complete a lang with utility function that could have been embedded :-) So for my question sake the answer is test empty+is_array – koalaok Sep 23 '16 at 09:13
@DonCallisto The _number_ of boolean conditions you concatenate does not lower readability. In contrary, blowing those checks up over a full page does. It is more a question of indentation. It is absolutely obvious to a programmer how those boolean operators behave. I personally place the `&&` (or whatever operator) at the _beginning_ of each line. That makes things crystal clear. – arkascha Sep 23 '16 at 09:14
@Koalaok ... You Got It.. go kick some App!.. ;-) – Emz Sep 23 '16 at 09:19
@Koalaok ... before I forgot.. you don't have to separate the condition.. you can use Logical && ... ;-) – Emz Sep 23 '16 at 09:37

Correct way to check (with PHP) a variable before looping through?

2 Answers2