从数组查找key对应的值

Question

php$arr=[5=>'name',8=>'age',10=>'city'];
$num='5,10';
$str='';
//如何查找5,10对应的值，就是输出'name,city',除了foreach还有什么更方便的办法?
foreach($arras$key=>$value){
if(strpos($num,$key)!==false){
$str.=$value;
}
}

Answer 1

$arr=array(5=>'name',8=>'age',10=>'city');$num='5,10';var_dump(array_intersect_key($arr,array_flip(explode(',',$num))));//outputarray(size=2)5=>string'name'(length=4)10=>string'city'(length=4)

Answer 2