How to get list of array keys with null values?

Question

I have an array. How can I get a list of the keys that have null values? Is there some short way to find them?

JohnK · Accepted Answer · 2014-07-29 14:22:11Z

10

Actually, array_keys has an optional search_value parameter, so you can just put:

array_keys($array, null, true);

You must set the third parameter (strict comparison) to true for it to match only nulls.

JohnK

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answered Jul 28, 2014 at 21:00

Don't Panic

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1 Comment

Thanks! This is the kind of answer I was looking for. Very educational!

JohnK · Accepted Answer · 2014-07-28 20:47:32Z

2

Here's the function that I came up with:

function find_nulls($a) {
    return array_keys(array_filter($a, function($b) {
       return is_null($b);
    }) );
}

It seems to work as desired.

answered Jul 28, 2014 at 20:47

JohnK

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