Tower of Hanoi solution implementation in PHP. Contents are also displayed

hanoi.php

<?php

//Tower of Hanoi (n-disk) algorithm in PHP with Display of Pole Contents

//the 3 poles representation
$poles=array(array(),array(),array());

function TOH($n,$A="S",$B="I",$C="D"){
	
	if($n>0){
		TOH($n-1,$A,$C,$B);
		echo "Move $A to $C \n";
		move($A,$C);
		dispPoles();
		
		TOH($n-1,$B,$A,$C);
	}
	else{
		return;
	}
}

function initPoles($n){
	global $poles;

	for($i=$n;$i>=1;--$i){
		$poles[0][]=$i;
	}
}


function move($source,$destination){
	global $poles;
	
	//get source and destination pointers
	if($source=="S") $ptr1=0;
	elseif($source=="I") $ptr1=1;
	else $ptr1=2;
	
	if($destination=="S") $ptr2=0;
	elseif($destination=="I") $ptr2=1;
	else $ptr2=2;
	
	$top=array_pop($poles[$ptr1]);
	array_push($poles[$ptr2],$top);
}

function dispPoles(){  
	global $poles;
	echo "S: [".implode(",",$poles[0])."] \n";
	echo "I: [".implode(",",$poles[1])."] \n";
	echo "D: [".implode(",",$poles[2])."] \n";
	echo "\n\n";
}

$numdisks=5;
initPoles($numdisks);
echo "Tower of Hanoi Solution for $numdisks disks: \n\n";
dispPoles();
TOH($numdisks);

?>

Sample output:
Tower of Hanoi Solution for 4 disks:

S: [4,3,2,1]
I: []
D: []

Move S to I
S: [4,3,2]
I: [1]
D: []

Move S to D
S: [4,3]
I: [1]
D: [2]

Move I to D
S: [4,3]
I: []
D: [2,1]

Move S to I
S: [4]
I: [3]
D: [2,1]

Move D to S
S: [4,1]
I: [3]
D: [2]

Move D to I
S: [4,1]
I: [3,2]
D: []

Move S to I
S: [4]
I: [3,2,1]
D: []

Move S to D
S: []
I: [3,2,1]
D: [4]

Move I to D
S: []
I: [3,2]
D: [4,1]

Move I to S
S: [2]
I: [3]
D: [4,1]

Move D to S
S: [2,1]
I: [3]
D: [4]

Move I to D
S: [2,1]
I: []
D: [4,3]

Move S to I
S: [2]
I: [1]
D: [4,3]

Move S to D
S: []
I: [1]
D: [4,3,2]

Move I to D
S: []
I: []
D: [4,3,2,1]