Create a Counter in AS3.0: to count the variables added to the stage.

When I create a lot of objects on the screen of similar 'meaning' (banners, news items, whatever) I track similar items by storing a reference to each of them in an array. If you're tracking lots of different types of things then I make an array of arrays and hold references to separate items in each.

I would use a Vector if you know the type will be constant for even more speed with lots of objects.

e.g. ref array

var references:Array = new Array();

references[0] = new Array(); // for stars

references[1] = new Array(); // for clouds

references[2] = new Array(); // for.. um.. planes?

function myTimerWantsAStar():void

{

    // creating a star

    references[0].push(createMeAStarAndReturnAReference());

}

function myTimerWantsACloud():void

{

    // creating a cloud

    references[1].push(createMeACloudAndReturnAReference());

}

function myTimerWantsAPlane():void

{

    // creating a plane

    references[2].push(createMeAPlaneAndReturnAReference());

}

As your timers add instances you just push them into their respective array. Then you easily can find out how many stars you have with references[0].length. Or you can aggregate them all with a loop over the array that tallies the .length property like var totalNum:int = 0; for (var i:int = 0; i < references.length; i++) { totalNum += references.length; }. No real rocket science.

You can also easily access each item for any purpose, such as adjusting it, removing it, etc by iterating the array.

for your purposes, you don't need to create one.  flash already has a counter property you can use, numChildren:

stage.numChildren

that doesn't distinguish movieclips from other displayobjects but it doesn't appear that matters for your needs.