using array_keys and getting unexpected result

Question

I have an array that is assigned to $elements. When I use array_keys to get the keys, I get what you would expect.

print_r(array_keys($elements));

Results in:

Array
(
    [0] => anchor-namecontentblock_areaBlock0contentblock11_1
    [1] => anchor-namecontentblock_areaBlock0contentblock22_1
    [2] => anchor-namecontentblock_areaBlock0contentblock33_1
...

But when I try to use array_keys with a search value, I get an empty array.

print_r(array_keys($elements, "anchor-namecontentblock_areaBlock0contentblock11_1"));

Should the result not be:

Array
(
    [0] => 0
)

Am I missing something?

@Rizier123 The array being printed out here is the result of array_keys($elements) not the original array. array_search() is to search for values, not keys. — D4V1D
– D4V1D, Commented Mar 25, 2015 at 21:44
@D4V1D From the manual: Searches the array for a given value and returns the corresponding key if successful So OP wants to find the key from the value — Rizier123
– Rizier123, Commented Mar 25, 2015 at 21:47

Marc B · Accepted Answer · 2015-03-26 13:53:09Z

4

You're doing the wrong array_keys search. Your anchor-name... values are KEYS in the original array, not VALUES. As such, your array_keys search argument is useless - it'll be searching the values of the original array, e.g.

$foo = array(
   'anchor-namecontentblock_areaBlock0contentblock11_1' => 'somevalue'
   etc..
                            searched by array_keys---------^^^^^^^^^^

You'd need do something more like:

$results = array_search('anchor-name...', array_keys($elements)));
           ^^^^^^^^^^^^^

instead.

edited Mar 26, 2015 at 13:53

answered Mar 25, 2015 at 21:48

Marc B

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1 Comment

Pablo Oliva Over a year ago

Awesome. Thanks MB. Just to clarify though, array_search requires the string as the 1st parameter and the array as the 2nd: array_search('anchor-name...', array_keys($elements));

Tom Fenech · Accepted Answer · 2015-03-25 21:47:34Z

3

Specifying a search parameter to array_keys allows you to retrieve the key(s) corresponding to one or more values in your array. You're passing it one of your array keys, so the function is returning no results.

answered Mar 25, 2015 at 21:47

Tom Fenech

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