PHP：取消设置$ _SESSION数组

Question

I have a session of arrays named:

$_SESSION['A'];

it contains

$_SESSION['A'][0] = 'A';
$_SESSION['A'][1] = 'B';

I can unset the $_SESSION['A']; using

unset($_SESSION['A']);

it unset all the value in the array how can I unset all value stored in

$_SESSION['A']; 

exept

$_SESSION['A'][0];
$_SESSION['A'][1];

I've seen this POST

which it unset all $_SESSION exept some stored in array. I used this code to unset it on array but I don't know how to used it as arrays.

$keys = array('x', 'y');
$_SESSION = array_intersect_key($_SESSION, array_flip($keys));

Answer 1

use array_slice like this:

$_SESSION['A'] = array_slice($_SESSION['A'], 0, 2);

Update:

Also, for non sequential indexes we can create this function:

  function array_pick($picks, $array)
    {
     $temp = array();
        foreach($array as $key => $value)
        {
            if(in_array($key, $picks))
            {
                $temp[$key] = $value;
            }
        }
     return array_values($temp);// or just $temp to keep original indexes
    }

PHPFiddle