sorting date associative array [duplicate]

Question

Possible Duplicate:
Sorting an associative array in PHP

I have this array

array
  0 => 
    array
      'start_date' => string '2012-11-14' (length=10)
      'end_date' => string '2012-11-19' (length=10)
  1 => 
    array
      'start_date' => string '1980-10-10' (length=10)
      'end_date' => string '1980-10-10' (length=10)
  2 => 
    array
      'start_date' => string '2012-11-20' (length=10)
      'end_date' => string '2099-10-10' (length=10)

I want to sort it on start_date. I dont think sort() method works on it. Any idea?

php.net/manual/en/function.usort.php

Blazemonger
– Blazemonger

2012-10-26 18:47:36 +00:00
Commented Oct 26, 2012 at 18:47 — Blazemonger
– Blazemonger, Commented Oct 26, 2012 at 18:47

Yanick Rochon · Accepted Answer · 2012-10-26 18:52:25Z

2

You can use usort :

PHP 5.3+

usort($array, function($a, $b) {
   //return strtotime($a['start_date']) - strtotime($b['start_date']);
   return strcmp($a['start_date'], $b['start_date']);
});

Older versions of PHP

function startDateCmp($a, $b) {
   //return strtotime($a['start_date']) - strtotime($b['start_date']);
   return strcmp($a['start_date']), $b['start_date']);
}

usort($array, 'startDateCmp');

edited Oct 26, 2012 at 18:52

answered Oct 26, 2012 at 18:47

Yanick Rochon

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4 Comments

complex857 Over a year ago

Actually, anonymous functions was introduced with php 5.3

Marc B Over a year ago

in this particular case, strtotime is overkill. the dates are already in a string format that can be sorted directly. but otherwise yes, you'd have to convert to a timestamp before comparing.

Yanick Rochon Over a year ago

@MarcB, I like to play safe, but you're right :)

Blazemonger Over a year ago

@MarcB Assuming certain dates are formatted "2012-05-01" and not "2012-5-1", you're right.

Chris Seymour · Accepted Answer · 2012-10-26 19:05:10Z

1

Use usort and supply your own function to do the ordering.

function cmp($a, $b)
{
    return $b['start_date'], $a['start_date'];
}

usort($array, "cmp");

edited Oct 26, 2012 at 19:05

answered Oct 26, 2012 at 18:47

Chris Seymour

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