[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"
}
我要计算size的和
（1）
echo array_sum(array_map(create_function('$val', 'return $val["size"];'), $arr));
或者
echo array_sum(array_map(function($val){return$val['size'];}, $arr));
（2）
$sum= 0;
foreach($arras as $item){
$sum += (int)$item['size'];
}