[RESOLVED] Help with sort nested associative arrays

[ifubad]

Trying to understand this code in a book, that is to sort nested associative arrays. But, it is not sorting the nested arrays correctly.

In the book, it’s using pass by reference. Since pass by reference is deprecated in the current PHP, I have actually tried setting the allow_call_time_pass_reference in the php.ini from the default of “off” to “on”, and have also tried return by reference, as in the code below, both giving the same incorrect results.

What am I missing?

Thank you in advance

<pre>
<?php
  function sortNestedArrayAssoc(&$a) {
    ksort($a);
    foreach ($a as $key => $value) {
      if (is_array($value)) {
        sortNestedArrayAssoc($value);
      }
    }
  }

  $arr = array(
    'Roman' =>
      array('one' => 'I', 'two' => 'II', 'three' => 'III', 'four' => 'IV'),
    'Arabic' =>
      array('one' => '1', 'two' => '2', 'three' => '3', 'four' => '4')
  );
  sortNestedArrayAssoc($arr);
  print_r($arr);
?>
</pre>

This is what the code is supposed to produce

Array
(
    [Arabic] => Array
        (
            [four] => 1
            [one] => 2
            [three] => 3
            [two] => 4
        )

[Roman] => Array
    (
        [four] => I
        [one] => II
        [three] => III
        [two] => IV
    )

)

This is what it’s actually producing

Array
(
    [Arabic] => Array
        (
            [one] => 1
            [two] => 2
            [three] => 3
            [four] => 4
        )

[Roman] => Array
    (
        [one] => I
        [two] => II
        [three] => III
        [four] => IV
    )

)

[laserlight]

ifubad wrote:

Since pass by reference is deprecated in the current PHP

It is not deprecated. What is deprecated is "call time pass by reference", e.g.,

foo(&$x);

in order to pass $x by reference to function foo. This is perfectly fine:

function foo(&$y)
{
    // use and modify $y
}

$x = 123;
foo($x);

ifubad wrote:

What am I missing?

Observe this line of your foreach loop:

foreach ($a as $key => $value) {

$value is a copy of $a[$key]. Notice also that you call:

sortNestedArrayAssoc($value);

Hence the recursive call operates on a copy of the nested array. One solution is to change the recursive call:

sortNestedArrayAssoc($a[$key]);

Another solution is to make $value a reference:

foreach ($a as &$value) {

[ifubad]

Laserlight,

I like the way you explain things, very clear and to the point. Thank you 🙂