PHP array flatten

phpArrayFlatten.php

<?php

function flatten($array)
{
  $result = [];

  foreach ($array as $item) {
    if (is_array($item)) {
      // recursive function and merge the result with existing result
      $result = array_merge($result, flatten($item));
    } else {
      $result[] = $item;
    }
  }

  return $result;
}

$sampleArray = [ [ 1, 2, [ 3 ] ], 4 ];
$flattenArray = flatten($sampleArray);
var_dump($flattenArray);