How to order an array by inner array key value?

Question

I have an array of arrays. I want to order these arrays by their ['date'] field. So the latest is at index [0]. How can I do this?

Here is an example of my print_r

$array=    (
    [0] => Array
        (
            [date] => 01/05/2013 12:00
            [location] => Town Hall
            [minutes] => mydomain.com
            [agenda] => 
        ),
 [1] => Array
        (
            [date] => 09/05/2013 12:00
            [location] => Town Hall
            [minutes] => mydomain.com/walker
            [agenda] => 
        )

)

you'll need http://www.php.net/manual/en/function.array-multisort.php — Twisted1919, May 28 '13 at 08:30
Also related and maybe easier to understand: [PHP, sort array of objects by object fields](http://stackoverflow.com/q/4282413/218196). — Felix Kling, May 28 '13 at 08:35

score 1 · Accepted Answer · answered May 28 '13 at 08:43

1

just try this -

$array = array(
    0 => array('date'=>'01/05/2013 12:00', 'location'=>'A'),
    1 => array('date'=>'09/05/2013 12:00', 'location'=>'B'),
    2 => array('date'=>'03/05/2013 12:00', 'location'=>'C'),
    3 => array('date'=>'02/05/2013 12:00', 'location'=>'D')
);

echo '<pre>';
print_r($array);
echo '</pre>';

function sorting($a, $b){
    $a = strtotime($a['date']);
    $b = strtotime($b['date']);

    if ($a == $b) {
        return 0;
    }
    return ($a < $b) ? -1 : 1;
}

usort($array, "sorting");

echo '<pre>';
print_r($array);
echo '</pre>';

see live demo - http://codepad.org/biXJgHQA

answered May 28 '13 at 08:43

HADI

2,829
1
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26

:) my pleasure. You are most Nicola – HADI May 28 '13 at 08:56
Related question, would I be better storing it as a different format if I want to then check the first array date to see if it's in the future? – Claire May 28 '13 at 08:57
If you can sort it in first that will be better. Then you don't need to usort your array again. probably you are fetching your data from database. if so then write appropriate query for that. If not then you may need to use usort after getting full array – HADI May 28 '13 at 09:08

score 0 · Answer 2 · answered May 28 '13 at 08:30

0

Try this:

usort($array,function($a,$b){
    return strcmp($a['date'],$b['date']);
}

or if PHP < 5.3

function my_sort($a,$b){
    return strcmp($a['date'],$b['date']);
}
usort($array,'my_sort');

answered May 28 '13 at 08:30

StampyCode

7,218
3
28
44

1

and what if php < 5.3 ? – Twisted1919 May 28 '13 at 08:31
`function my_sort($a,$b){ return strcmp($a['date'],$b['date']); } usort($array,'my_sort');` – StampyCode May 28 '13 at 08:33
@TimStamp better update the answer instead of putting it in comment. – Bibhas Debnath May 28 '13 at 08:34
`strcmp` on date fields doesn't sound like a good idea. – Jon May 28 '13 at 08:34
that's why `array_multisort` is a better approach. – Twisted1919 May 28 '13 at 08:35
If the dates are formatted like this, then `strcmp` won't work indeed. `20/01/2013` is "larger" than `01/02/2013`. – Felix Kling May 28 '13 at 08:37
@Twisted1919: `array_multisort` is not a magic potion that will fix all your problems. It would not solve the date/time sorting problem here. And generally speaking, it offsets being slightly easier to use by being much more wasteful to boot. – Jon May 28 '13 at 08:37
@FelixKling Yes its doesn't seem to be working as the date is being returned like this – Claire May 28 '13 at 08:37
You'll have to format the date in UTC date format, or as a unix timestamp first. – StampyCode May 28 '13 at 08:39
whats a UTC date format? – Claire May 28 '13 at 08:41
@Tim: UTC is a time standard, not a format. The format ISO 8061 would do fine (http://en.wikipedia.org/wiki/ISO_8601). – Felix Kling May 28 '13 at 08:43
It's a universal standard where the date is written as something similar to `YYYY-MM-DD HH-MM-SS +XXXX` - this also (usefully) makes it string sortable. – StampyCode May 28 '13 at 08:44
You're right I meant ISO 8601, but UTC is easier to remember ;) – StampyCode May 28 '13 at 08:45

How to order an array by inner array key value?

2 Answers2