php return array key of first element?

Question

I have an assoc array in PHP which I am sorting by value. After sorting I need to return the key of the first element.

Example array:

Array
(
    [a] => 42.857142857143
    [b] => 87.5
    [c] => 50
    [d] => 61.538461538462
)

Then I use asort(), and the array looks like this:

Array
(
    [b] => 87.5
    [d] => 61.538461538462
    [c] => 50
    [a] => 42.857142857143
)

How can I return "b" (as it is the key of the first array)?

Whoops, misread. Can't delete. Disregard. :)

SenorAmor
– SenorAmor

2014-01-22 20:54:24 +00:00
Commented Jan 22, 2014 at 20:54 — SenorAmor
– SenorAmor, Commented Jan 22, 2014 at 20:54
@SenorAmor - nick of time ;)

scrowler
– scrowler

2014-01-22 20:57:40 +00:00
Commented Jan 22, 2014 at 20:57 — scrowler
– scrowler, Commented Jan 22, 2014 at 20:57

jeroen · Accepted Answer · 2014-01-22 21:07:43Z

3

You can use key() in combination with reset() to make sure you have the first element:

reset($arr);
$key = key($arr);

edited Jan 22, 2014 at 21:07

answered Jan 22, 2014 at 20:54

jeroen

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3 Comments

l'L'l Over a year ago

Now the only question is which came first, the key or the array? :D

Kolja Over a year ago

I tried it and key is empty in my case. :( *Edit: If I understand the php.net documentation, reset returns a string, and so I can't get the key from a string.

jeroen Over a year ago

@koljanep You're right, that was too fast, you need to reset the array seperately and then get the key, see my edit: codepad.viper-7.com/23fMsh

Mike Brant · Accepted Answer · 2014-01-22 21:24:27Z

3

reset() the array pointer to the first item and then call key().

reset($array);
$key = key($array);

Or you can use array_keys().

$array_keys = array_keys($array);
$key = $array_keys[0];

edited Jan 22, 2014 at 21:24

answered Jan 22, 2014 at 20:54

Mike Brant

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1 Comment

jeroen Over a year ago

+1 You were right, you need to do it in two steps. I wonder why it was downvoted though...

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