Implementation Of Stack Class and Pointer Approach

<?php

/*
 *
 * @Author: Zuhair Mirza
 * @First Implementation Of Stack Class and Pointer Approach
 * @Date : 30-July-2013
 *
 */


$s = new Stack();
$s->push(1);
$s->push(2);
$s->push(3);

// 3 2 1
echo $s;

$s->pop();
$s->pop();

// 1
echo $s;


class Struct {

    protected $_data = null;
    protected $_next = null;

    public function __construct($data, $next) {
        $this->_data = $data;
        $this->_next = $next;
    }

    public function getData() {
        return $this->_data;
    }

    public function setData(&$data) {
        $this->_data = $data;
    }

    public function getNext() {
        return $this->_next;
    }

    public function setNext(&$next) {
        $this->_next = $next;
    }

}

class Stack {

    protected $_top = null;

    public function push($data) {
        $item = new Struct($data, null);

        if ($this->_top == null) {
            $this->_top = $item;
        } else {
            $item->setNext($this->_top);
            $this->_top = $item;
        }
    }

    public function pop() {
        if ($this->_top) {
            $t = $this->_top;
            $data = $t->getData();

            $this->_top = $this->_top->getNext();

            $t = null;

            return $data;
        }
    }

    public function __toString() {
        $output = '';
        $t = $this->_top;
        while ($t) {
            $output .= $t->getData() . ' ';
            $t = $t->getNext();
        }

        return $output;
    }

}


/*
 * ----------------------THE END-----------------------
 */

?>