PHP array_insert_after() & array_insert_before()

November 15, 2011 - 4:22pm — brad

I need to insert a key/value at a certain position in an associative array. It seems like a common issue. I was surprised to discover there wasn't a straightforward answer. Here is the method I created. If you know of a more efficient method, please let me know in the comments.
I located: http://stackoverflow.com/questions/1286853/how-to-efficiently-insert-ele... The number of array_* function calls in the selected answer must be inefficient.

/*
 * Inserts a new key/value before the key in the array.
 *
 * @param $key
 *   The key to insert before.
 * @param $array
 *   An array to insert in to.
 * @param $new_key
 *   The key to insert.
 * @param $new_value
 *   An value to insert.
 *
 * @return
 *   The new array if the key exists, FALSE otherwise.
 *
 * @see array_insert_after()
 */
function array_insert_before($key, array &$array, $new_key, $new_value) {
  if (array_key_exists($key, $array)) {
    $new = array();
    foreach ($array as $k => $value) {
      if ($k === $key) {
        $new[$new_key] = $new_value;
      }
      $new[$k] = $value;
    }
    return $new;
  }
  return FALSE;
}
 
/*
 * Inserts a new key/value after the key in the array.
 *
 * @param $key
 *   The key to insert after.
 * @param $array
 *   An array to insert in to.
 * @param $new_key
 *   The key to insert.
 * @param $new_value
 *   An value to insert.
 *
 * @return
 *   The new array if the key exists, FALSE otherwise.
 *
 * @see array_insert_before()
 */
function array_insert_after($key, array &$array, $new_key, $new_value) {
  if (array_key_exists($key, $array)) {
    $new = array();
    foreach ($array as $k => $value) {
      $new[$k] = $value;
      if ($k === $key) {
        $new[$new_key] = $new_value;
      }
    }
    return $new;
  }
  return FALSE;
}

Tags: 
PHP arrays insert

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