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This chapter is from the book

This chapter is from the book

Sorting Nested Arrays

function sortNestedArray(&$a) {
  sort($a);
  for ($i = 0; $i < count($a); $i++) {
    if (is_array($a[$i])) {
      sortNestedArray($a[$i]);
    }
  }
}
<pre>
<?php
  function sortNestedArray(&$a) {
    sort($a);
    for ($i = 0; $i < count($a); $i++) {
      if (is_array($a[$i])) {
        sortNestedArray($a[$i]);
      }
    }
  }

  $arr = array(
    'French',
    'Spanish',
    array('British English', 'American English'),
    'Portuguese',
    array('Schwitzerdütsch', 'Deutsch'),
    'Italian'
  );
  sortNestedArray($arr);
  print_r($arr);
?>
</pre>

Sorting a Nested Array Using a Recursive Function (sortNestedArray.php)

The standard sorting functions of PHP do not traverse nested arrays when performing their operations. However, if you use a recursive function, you can code this in just a few lines.

The goal is to sort an array that is nested but consists only of numeric subarrays so that only numeric (and, therefore, useless) keys are used.

The idea is the following: Calling sort() does sort the array, but leaves out all subarrays. Therefore, for all elements that are arrays, the sorting function is called again, recursively. The preceding code shows this concept; Figure 2.4 shows the result for a sample array.

Figure 2.4

Figure 2.4. Sorting nested arrays

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