note 98025 added to function.array-merge

<?php
function array_merge_zipper(&$output, $one = array(), $two = array(), $same_size= TRUE) {

  if ($same_size) {
    // Return FALSE if the arrays differ in size.
    if (count($one) != count($two))
      return FALSE;
    $number = count($one);
  } else {
    // Count as high as the smallest array.
    $number = min(count($one), count($two));
  }

  // Empty the output array.
  $output = array();

  // Merge.
  for ($i = 0; $i < $number; $i++) {
    $output[] = $one[$i];
    $output[] = $two[$i];
  }

  // Return success.
  return TRUE;
}
?>

This function merges two arrays into one, alternating between the two arrays. Given:

$one = array('apple', 'pear');
$two = array('blue', 'red');
$output = array();
array_merge_zipper(&$output, $one, $two, TRUE);

$output would be:

array(
  0 => 'apple',
  1 => 'blue',
  2 => 'pear',
  3 => 'red'
);

The $same_size flag is to note whether both input arrays contain the same number of items. If not, setting the flag to FALSE will make the function merge up to the number of items in the smallest of the two input arrays.

The following function does essentially the same, but preserves array keys. It'll return FALSE if the input arrays share a key between them or if the  arrays differ in size.

<?php
function array_merge_zipper_key(&$output, $one = array(), $two = array()) {
  // Return FALSE if the arrays differ in size.
  if (count($one) != count($two))
    return FALSE;

  // Returns FALSE if the arrays share a key.
  if (count(array_keys_intersect($one, $two)))
    return FALSE;
  
  // Empty the output array.
  $output = array();

  // keys!  
  $one_keys = array_keys($one);
  $two_keys = array_keys($two);

  // Merge.
  for ($i = 0; $i < count($one); $i++) {
    $output[$one_keys[$i]] = $one[$one_keys[$i]];
    $output[$two_keys[$i]] = $two[$two_keys[$i]];
  }

  // Return success.
  return TRUE;
}
----
Server IP: 117.104.162.229
Probable Submitter: 150.101.221.106
----
Manual Page -- http://www.php.net/manual/en/function.array-merge.php
Edit        -- https://master.php.net/note/edit/98025
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