Adjacency list representation of undirected graph in php

Php program for Adjacency list representation of undirected graph. Here problem description and explanation.

<?php
/*
    Php Program for 
    Undirected graph representation by using adjacency list 
*/
class AjlistNode
{
	// Vertices node key
	public $id;
	public $next;
	public	function __construct($id)
	{
		// Set value of node key
		$this->id = $id;
		$this->next = NULL;
	}
}
class Vertices
{
	public $data;
	public $next;
	public $last;
	public	function __construct($data)
	{
		$this->data = $data;
		$this->next = NULL;
		$this->last = NULL;
	}
}


class Graph
{
	// Number of Vertices
	public $size;
	public $node;
	public	function __construct($size)
	{
		// Set value
		$this->size = $size;
		$this->node = array_fill(0, $size, NULL);
		$this->setData();
	}
	// Set initial node value
	public	function setData()
	{
		if ($this->size <= 0)
		{
			printf("\nEmpty Graph\n");
		}
		else
		{
			for ($index = 0; $index < $this->size; $index++)
			{
				$this->node[$index] = new Vertices($index);
			}
		}
	}
	// Connect two nodes
	public	function connect($start, $last)
	{
		$edge = new AjlistNode($last);
		if ($this->node[$start]->next == NULL)
		{
			$this->node[$start]->next = $edge;
		}
		else
		{
			// Add edge at the end
			$this->node[$start]->last->next = $edge;
		}
		// Get last edge 
		$this->node[$start]->last = $edge;
	}
	//  Handling the request of adding new edge
	public	function addEdge($start, $last)
	{
		if ($start >= 0 && $start < $this->size && 
            $last >= 0 && $last < $this->size)
		{
			$this->connect($start, $last);
			if ($start == $last)
			{
				// When self loop
				return;
			}
			$this->connect($last, $start);
		}
		else
		{
			// When invalid nodes
			printf("\nHere Something Wrong\n");
		}
	}
	public	function printGraph()
	{
		if ($this->size > 0)
		{
			// Print graph ajlist Node value
			for ($index = 0; $index < $this->size; ++$index)
			{
				printf( "\nAdjacency list of vertex %d :",$index);
				$temp = $this->node[$index]->next;
				while ($temp != NULL)
				{
					// Display graph node 
					printf(" %d",$this->node[$temp->id]->data);
					// Visit to next edge
					$temp = $temp->next;
				}
			}
		}
	}
	public static function main($args)
	{
		// 5 implies the number of nodes in graph
		$g = new Graph(5);
		// Connect node with an edge
		$g->addEdge(0, 1);
		$g->addEdge(0, 2);
		$g->addEdge(0, 4);
		$g->addEdge(1, 2);
		$g->addEdge(1, 4);
		$g->addEdge(2, 3);
		$g->addEdge(3, 4);
		// print graph element
		$g->printGraph();
	}
}

Graph::main(array());

Output

Adjacency list of vertex 0 : 1 2 4
Adjacency list of vertex 1 : 0 2 4
Adjacency list of vertex 2 : 0 1 3
Adjacency list of vertex 3 : 2 4
Adjacency list of vertex 4 : 0 1 3