A short implementation of a stack in PHP.

Example usage:

<?php
 
$s = new Stack(array(3, 4, 5));
$s->push("6");
print $s->pop();
print $s->pop();
print $s->pop();
print $s->pop();

<?php
 
###########################################################################
##  Copyright (C) Wizardry and Steamworks 2016 - License: GNU GPLv3      ##
###########################################################################
class Stack
{
    protected $stack;
    protected $size;
 
    public function __construct($elements = array()) {
        switch(empty($elements)) {
            case TRUE:
                $this->stack = array();
                $this->size = 0;
                break;
            default:
                $this->stack = $elements;
                $this->size = count($elements);
                break;
        }
    }
 
    public function push($element) {
        array_unshift($this->stack, $element);
        ++$this->size;
    }
 
    public function pop() {
        if ($this->isEmpty())
            throw new RunTimeException('Stack is empty!');
        --$this->size;
        return array_shift($this->stack);
    }
 
    public function peek() {
        return current($this->stack);
    }
 
    public function isEmpty() {
        return $this->size == 0;
    }
}