How to merge arrays

How to merge arrays // for example, the following two arrays $ a1 = array (2 = & gt; array (1, 2), 3 = & gt; array (4 )); $ a2 = array (2 = & gt; array (5), 5 = & gt; array (4 )); /*** the result of merging $ a1 and $ a2 is & nbsp; array (2 = & gt; a. how to merge arrays?

// For example, the following two arrays
$ A1 = array (2 => array (1, 2), 3 => array (4 ));
$ A2 = array (2 => array (5), 5 => array (4 ));
/**
* The result of merging $ a1 and $ a2 is array (2 => array (1, 2, 5), 3 => array (4 ), 5 => array (4 ));
**/

Is there any good method? Share To: array (1, 2), 3 => array (4); $ a2 = array (2 => array (5), 5 => array (4 )); /*** me... 'data-pics = ''>
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$keys = array_unique(array_keys(array_merge($arr1, $arr2)));
foreach($keys as $k) {
 .....
}

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If we do not consider further recursion, every time we merge two-dimensional arrays, we can directly write a loop and then what about array_merge?
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Upstairs...
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$a1 = array(2=>array(1,2),3=>array(4));
$a2 = array(2=>array(5),5=>array(4));

foreach($a2 as $k=>$v) {
  if(isset($a1[$k])) $a1[$k] = array_merge($a1[$k], $v);
  else $a1[$k] = $v;
}
print_r($a1);

Array
(
[2] => Array
(
[0] => 1
[1] => 2
[2] => 5
)

[3] => Array
(
[0] => 4
)

[5] => Array
(
[0] => 4
)

)