Join two or more arrays of arrays

Question

Suppose I have two arrays like the following:

$arr2 = array(array("first", "second"), array("third", "fourth"));
$arr3 = array(array("fifth", "sixth", "seventh"), array("eighth", "ninth"), array("tenth", "eleventh"));

And I want a result like this:

$arr4 =  array("first", "second", "third", "fourth", "fifth", "sixth", "seventh","eighth", "ninth","tenth", "eleventh" );

How to do that? in PHP

Answer 1

What you want to is flatten and combine the arrays. There's a nice function for flattening in the comments in the PHP manual of array_values, http://www.php.net/manual/en/function.array-values.php#104184

Here's the code:

/**
 * Flattens an array, or returns FALSE on fail.
 */
function array_flatten($array) {
  if (!is_array($array)) {
    return FALSE;
  }
  $result = array();
  foreach ($array as $key => $value) {
    if (is_array($value)) {
      $result = array_merge($result, array_flatten($value));
    }
    else {
      $result[$key] = $value;
    }
  }
  return $result;
}

Just run this on array($arr2, $arr3).

Answer 2

function flatten($ar,&$res) {
  if (is_array($ar))
    foreach ($ar as $e) flatten($e,$res);
  else
    $res[]=$ar;
}

$arr2 = array(array("first", "second"), array("third", "fourth"));
$arr3 = array(array("fifth", "sixth", "seventh"), array("eighth", "ninth"), array("tenth", "eleventh"));

$arr4=array();
flatten($arr2,$arr4);
flatten($arr3,$arr4);