PHP usort function on object array not working

Question

I have the following object array:

 array (
   0 => MyObject::__set_state(array(
      'id' => '1176',
      'value' => 'Oranges',
   )),
   1 => MyObject::__set_state(array(
      'id' => '1178',
      'value' => 'Bananas',
   )),
   2 => MyObject::__set_state(array(
      'id' => '1179',
      'value' => 'grapes',
   )),
 )

I want to sort ascending by value so I use the following:

usort($myObjectArray, function($a, $b) {
    return strcmp($a->value, $b->value);
});

But I'm nothing is sorted?

Make sure you convert them to a uniform case before comparing. `return strcmp(strtolower($a->value), strtolower($b->value));` — nice_dev, Jan 14 '20 at 10:12
@RiggsFolly looks like strcmp is case sensitve. Changing `grapes` to `Grapes` fixes it — adam78, Jan 14 '20 at 10:19
@adam78 "Looks like" sounds a bit strange, as this is one of the little documentation sentences on php.net/strcmp — Nico Haase, Jan 14 '20 at 10:26

score 0 · Answer 1 · answered Jan 14 '20 at 10:23

0

You can do like this:

function cmp($a, $b) {
    return strcmp($a->value, $b->value);
}); 
usort($myObjectArray,"cmp");

answered Jan 14 '20 at 10:23

Arijit Jana

220
1
4

Please add some explanation to your answer - what makes you think that this behaves different? – Nico Haase Jan 14 '20 at 10:25

score 0 · Answer 2 · answered Jan 14 '20 at 10:38

From php 7, you can use the spaceship operator in the comparison function.

I just tested it with the below code and it worked as you would have expected without any need to make the case uniform.

Note: I just made an array of stdClass objects by casting arrays.

$objArr = [
   (Object) [
      'id' => '1176',
      'value' => 'Oranges',
   ],
   (Object) [
      'id' => '1178',
      'value' => 'Bananas',
   ],
   (Object) [
      'id' => '1179',
      'value' => 'grapes',
   ],
];

usort($objArr, function($a, $b) {
    // use return $b->value <=> $a->value; 
    // to reverse order
    return $a->value <=> $b->value;
});

which results in the following:

print_r($objArr);

Array
(
    [0] => stdClass Object
        (
            [id] => 1178
            [value] => Bananas
        )

    [1] => stdClass Object
        (
            [id] => 1176
            [value] => Oranges
        )

    [2] => stdClass Object
        (
            [id] => 1179
            [value] => grapes
        )

)

Useful if case is an issue (i.e should grapes and Grapes be sorted).

Dmitry Leiko · Answer 3 · 2020-01-14T16:23:46.257

You can try code below. I checked it's work fine:

class MyObject
{
    public $id;
    public $value;
}

$a = [];

$ob = new MyObject();
$ob->id = '1176';
$ob->value = 'Lemons';

$ob2 = new MyObject();
$ob2->id = '1178';
$ob2->value = 'apples';

$ob3 = new MyObject();
$ob3->id = '1179';
$ob3->value = 'grapes';

$a[] = $ob;
$a[1] = $ob2;
$a[2] = $ob3;

usort( $a, function($a, $b) {
    return strcmp(mb_strtolower($a->value), mb_strtolower($b->value));
});


print_r($a);

Output:

Array
(
    [0] => MyObject Object
        (
            [id] => 1178
            [value] => apples
        )

    [1] => MyObject Object
        (
            [id] => 1179
            [value] => grapes
        )

    [2] => MyObject Object
        (
            [id] => 1176
            [value] => Lemons
        )

)

Also you can check the - Doc

PHP usort function on object array not working

3 Answers3