Data Structures for PHP Devs: Stacks and Queues with Example

Two basic abstract data types — stack and queue.

What is Stacks?

A stack is a sequential collection with a particular property, in that, the last object placed on the stack, will be the first object removed. This property is commonly referred to as last in first out, or LIFO.

• init — create the stack.
• push — add an item to the top of the stack.
• pop — remove the last item added to the top of the stack.
• top — look at the item on the top of the stack without removing it.
• isEmpty — return whether the stack contains no more items.

Example:

array_shift() — Removes the first element in the array.

array_unshift() — Added new variables as the first element in the array.

Let’s add some items to the stack:

$stack = new Stack(10, array(1, 2, 3, 4, 5));
//OR
$stack = new Stack();
$stack->push(1);
$stack->push(2);
$stack->push(3);
$stack->push(4);

To remove some items from the stack:

echo $stack->pop(); // outputs '4'

Let’s see what’s at the top of the stack:

echo $stack->top(); // outputs '3'

Thanks for reading out.

Reference From: https://www.sitepoint.com/php-data-structures-1/