Get Element at N position in an Array without Loop

How get you get element key and value of an at the n position array at a particular position without loop.

Imagine

$postion = 3; // get array at 3rd position
$array = array(
        "A" => "Four",
        "B" => "twp",
        "C" => "three",
        "D" => "Four",
        "E" => "Five",
        "F" => "Four");


$keys = array_keys($array);
$value = array_values($array);

echo implode(array_slice($keys, $postion, 1)), PHP_EOL; // Key at 3rd posstion
echo implode(array_slice($value, $postion, 1)), PHP_EOL; // Value at n position

Output

D
Four

Issues With the method is

Why not use loop

Why not use a Database

Why not use SplFixedArray

Fatal error: Uncaught exception 'InvalidArgumentException' 
with message 'array must contain only positive integer keys' 

What do you mean by large data set :

Am sure something like fseek for array would do the trick .. but not sure if that exists

Assuming PHP 5.4, with array dereferencing:

echo $array[array_keys($array)[$position]];

In earlier versions you need to break it into two lines:

$keys = array_keys($array);
echo $array[$keys[$position]];

It would also be worth using the two-line approach in 5.4+ if you have to access multiple elements, to allow you to only call the relatively expensive array_keys() function once. Also the dereferencing approach assumes that the specific position within the array exists, which it may not. Breaking it into multiple operations would allow you to handle that error case.

Although of course you don't ever need access to the key, you can simply do:

echo array_values($array)[$position];
// or
$values = array_values($array);
echo $values[$position];

Edit

The ArrayIterator class can also do this for you:

$iterator = new ArrayIterator($array);
$iterator->seek($position);

echo $iterator->key(), " = ", $iterator->current(); // D = Four

This is probably the least expensive way to do this assuming it doesn't create a copy of the array in memory when you do it (still researching this element), and likely the best method for multiple accesses of arbitrary keys.

What you want is not possible. PHP's arrays have efficient access by key, but don't have efficient access by offset. The order is only available as a linked list, so the best efficiency you can hope for is an O(n) loop, which just goes through the array and looks for the offset:

$i = 0;
foreach ($array as $value) {
    if ($i++ === $offset) {
        // found value
    }
}

If you want this operation to be fast, then you'll have to use a proper, numerically and sequentially indexed array.

实际上你不需要$ values数组：

$keys = array_keys($array);

$value_3=$array[$keys[3]];

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