Stack [data type]

stack.php

<?php

class Stack
{
    /**
     * Items
     *
     * @var array
     */
    protected $items = [];

    /**
     * Items length
     *
     * @var integer
     */
    protected $itemsLength = 0;

    /**
     * Push
     *
     * @param mixed $value
     * @return void
     */
    public function push($value)
    {
        $this->itemsLength++;
        $this->items[] = $value;
    }

    /**
     * Pop
     *
     * @return mixed
     * @throws Exception
     */
    public function pop()
    {
        $lastItemIndex = $this->itemsLength - 1;

        if ($lastItemIndex < 0) {
            throw new Exception('There are no any items in stack');
        }

        $value = $this->items[$lastItemIndex];
        unset($this->items[$lastItemIndex]);
        $this->itemsLength--;

        return $value;
    }
}

$stack = new Stack();

// fill the stack
foreach (range(0, 12) as $value) {
    $stack->push($value);
}


// extract from the stack
foreach (range(0, 12) as $value) {
    echo $stack->pop() . '<br>';
}