Positive variable?

Let me start off by saying I’m a noob to AS in general but I am doing quite wll for just learning from tuts. Also I’m a little bit stoopid… but, aren’t we all from time to time?

Here’s my problem, building a photo gallery and I want my variable to always be a positive whole number, here’s the code for the buttons using UIimage loader etc.

var dinnerImageNum:Number = 1

function forwardImage (evtObj:MouseEvent):void{
//adding to the variable number, dinnerImagenum
//using the variable container
standardImageLoader.source = “gallery/dinner/dinner”+dinnerImageNum+".jpg";


function backImage (evtObj:MouseEvent):void{
//subtracting from the variable number, dinnerImagenum
standardImageLoader.source = “gallery/dinner/dinner”+dinnerImageNum+".jpg";


How do I make my var dinnerImageNum always equal to or greater than 1?

Was watching the lynda tuts, can ya tell?