[SOLVED] Sort array chronologically

[soycharliente]

I'm trying to sort an array chronologically. After a bit of searching, the best way I can find it to use uasort() with a callback function.

 

Can someone help me understand this example and how I could transform it to compare dates? The dates are in a multidimensional array.

$feed[0]['release_date']

 

<?php
// Comparison function
function cmp($a, $b) {
    if ($a == $b) return 0;
    return ($a < $b) ? -1 : 1;
}

// Array to be sorted
$array = array('a' => 4, 'b' => 8, 'c' => -1, 'd' => -9, 'e' => 2, 'f' => 5, 'g' => 3, 'h' => -4);
print_r($array);

// Sort and print the resulting array
uasort($array, 'cmp');
print_r($array);
?>

[Psycho]

What is the format of the date? That would determine how you compare the dates, but assuming the dates are in the format yyyymmdd, then you could do this:

 

function sortByreleaseDate($a, $b)
{
    if ($a['release_date'] = $b['release_date']) { return 0; }
    return ($a['release_date'] < $b['release_date']) ? -1 : 1;
}

uasort($feed, 'sortByReleaseDate');

[soycharliente]

It's stored as 2009-07-24 14:16:00 (I can easily concatenate the date and time together). And it's another dimension down in the array. Does that throw a wrench in the mix?

 

Array
(
    [0] => Array
        (
            [release_date] => 2009-07-24
            [release_time] => 14:16:00
            [display_start_date] => 2009-07-24
            [display_stop_date] => 2015-12-31
            [id] => 3179
            [title] => Event Title
            [summary] => A one sentence summary about the event.
            [img_embed] => 
            [img_alt] => 
        )

    [1] => Array
        (
            [release_date] => 2009-07-23
            [release_time] => 11:07:00
            [display_start_date] => 2009-07-23
            [display_stop_date] => 2009-09-01
            [id] => 3172
            [title] => Event Title
            [summary] => A one sentence summary about the event.
            [img_embed] => 
            [img_alt] => 
        )

    [2] => Array
        (
            [release_date] => 2009-07-09
            [release_time] => 11:55:00
            [display_start_date] => 2009-07-09
            [display_stop_date] => 2009-11-09
            [id] => 3130
            [title] => Event Title
            [summary] => A one sentence summary about the event.
            [img_embed] => 
            [img_alt] => 
        )
)

[soycharliente]

Buddy told me that $a and $b get passed associative arrays. Got it working now.

 

Final solution:

function cmp($a, $b) {
  if($a['display_start_date'] == $b['display_start_date']) { return 0; }
  return ($a['display_start_date'] > $b['display_start_date']) ? -1 : 1;
}
usort($feed, 'cmp');

 

Pretty close to what you had mjdamato (if not the exact same thing--it looks the same). I was messing with yours and showed them what you gave me. What I posted is what we eventually finished with.