php nested check for array key

Question

I have a situation where I want to check for a key 2 levels deep in a PHP array. So my code currently looks like...

    if(array_key_exists($needleBox, $haystack)) {
        if(array_key_exists($needle, $haystack[$needleBox])) {
            // do stuff with value attached to $needle
        }
    }

Where I first check for the array containing my needle ($needleBox), then check for the needle if $needleBox is found.

Is it safe to skip the check for $needleBox & use...

    if(array_key_exists($needle, $haystack[$needleBox])) {
        // do stuff with value attached to $needle
    }

or to check for both together in one if statement like...

    if(array_key_exists($needleBox, $haystack) && array_key_exists($needle, $haystack[$needleBox])) {
        // do stuff with value attached to $needle
    }

I consider the first alternative preferable for being more concise.

First alternative will throw a warning if that key doesn't exist so you will need to suppress that (using @). — Vinay
– Vinay, Commented Apr 21, 2018 at 4:24

ZeroOne · Accepted Answer · 2020-12-01 01:00:34Z

3

why dont you use isset. which i much more prefer it.. isset is much faster than array_key_exists. BTW isset will return false if the value is null..

if (isset($haystack[$needleBox]) && isset($haystack[$needleBox][$needle])) {
     //code
}

OR

if ($haystack[$needleBox][$needle] ?? null)) {
     //code
}

EDIT agreed with @shawn advise

if (isset($haystack[$needleBox][$needle])) {
     //code
}

edited Dec 1, 2020 at 1:00

answered Apr 21, 2018 at 4:27

ZeroOne

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4 Comments

Pedro Over a year ago

I like that, & will accept the answer as soon as allowed. Thank you.

shawn Over a year ago

You do NOT need to repeat the key check. just write isset($haystack[$needleBox][$needle]) is OK

B. Desai Over a year ago

Agreed with @shawn. If $haystack[$needleBox][$needle] is set it means $haystack[$needleBox] is also set

Pedro Over a year ago

This answer, & the comments, have me thinking I've been using array_key_exists in a lot of situations where isset would be more appropriate.

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