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))));
//output
array(size=2)
5=>string'name'(length=4)
10=>string'city'(length=4)
                            

Answer 2

$arr=array(5=>'name',8=>'age',10=>'city');
$num='5,10';
$str=array();
$explode=explode(',',$num);
foreach($explodeas$key){
if(array_key_exists($key,$arr)){
array_push($str,$arr[$key]);
}
}
echoimplode(',',$str);
?>