php中计算二维数组中某一元素之和

 <meta charset="utf-8">

<?php
$ar = array(
    2 => array(
        'catid' => '6',
		'cat' => 'dd',
        'catdir' => '1522332388000',//2018-03-29 22:06:28
    ),
    6=> array(
        'catid' => '5',
		'cat' => 'dd',
        'catdir' => '1522329351000'//2018-03-29 21:15:51
    ),
    7=> array(
        'catid' => '4',
		'cat' => 'ddfgd',
        'catdir' => '1522328237000'//2018-03-29 20:56:15
    ),
    9=> array(
        'catid' => '3',
		'cat' => 'dd',
        'catdir' => '1522327772000'//2018-03-29 20:49:32
    ),
    10=> array(
        'catid' => '2',
		'cat' => 'dvvd',
        'catdir' => '1522325351000'//2018-03-29 20:09:11
    ),
    5 => array(
        'catid' => '1',
		'cat' => 'ddfgd',
        'catdir' => '1522323606000',//2018-03-29 19:40:06
    ),

);

echo array_sum(array_map(create_function('$val', 'return $val["catid"];'), $ar));

?>

[0] => array(5) {
      ["id"] => string(2) "11"
      ["name"] => string(5) "1.jpg"
      ["suffix"] => string(3) "jpg"
      ["url"] => string(29) "./Uploads/1/5292f55d208e8.jpg"
      ["size"] => string(6) "715895"
    }
    [1] => array(5) {
      ["id"] => string(2) "12"
      ["name"] => string(22) "minisite数据库.docx"
      ["suffix"] => string(4) "docx"
      ["url"] => string(30) "./Uploads/1/5292f5606a52c.docx"
      ["size"] => string(5) "16667"
    }