Checking Checkboxes

Question

I'm a beginner, and I really don't know what I'm doing so your help is much appreciated. I've got a form with several checkboxes. I need to be able to click on a button which will figure out how many of the boxes are checked. How do I do this?

Answer 1

Since your using AS3, and CS3, you have the best of both worlds at your fingertips as far as the language and the help documentation goes (in CS4 they decided to no longer make the help docs readily avialable with the installation).  I've stayed away from CS4, but not for that reason... just too many bugs were prevalent when it came out--a rushed production I reckon.
Your background in the various languages you mention is a relief to hear... makes it a little easier to explain things.  Actionscript 3 is pretty much like any other language when it comes to coding logic, and is kinda a mixture of C and PHP and javascript... a similarity in the C OOP strictness, and the special functionality coding that you find with PHP.
I'll get to some code to kick you off in a bit, but first a briefing on the help docs vs. classes/objects in Flash.  In general, every class has some combination of Properties, Methods, Events, and Constants.  And the CS3/AS3 help docs have done a much better job of making things easier to find.  The easiest way to find class information is to open the help docs and select Actionscript 3.0 -> Actionscript 3.0 language and Component Reference -> All Classes, and then scroll thru the list to find the type of object/class you want to know about.  The information that appears will give an overview of the class and then list links to all of the Properties, Methods, Events, and Constants associated with that class.  Done with this.
When you add objects to the stage that you want to control, you need to assign instance names to them.  Instance names are assigned in the Properties panel, to the far left.  When you want to assign code to work with/for the objects, they need to be in the presence of that code.  Normally, folks will create layers specifically for actionscript to keep it separate from the visual elements/objects.  So you just need to be sure the code is in the same frame (vertically) on the timeline as the objects it going to work with.
Here's how you deal with coding objects to behave as buttons...
Let's say you create a button symbol.  Since it is a button, it is already a self animating object that will react to mouse interactions, but only visually at this stage.  The first thing you need to do to make it useful code-wise is to assign it a unique instance name.  So you drag a copy of it out to the stage from the library, and while it's still selected, you enter that unique instance name for it in the Properties panel... let's say you name it "btn1"
In AS3, to make a button work with code, you need to add an event listener for it.  You might need to add a few (for different events, like rollover, rollout, clicking it, but for now we'll just say you want to be able to click it to do something.  In the timeline that holds that button, in a separate actions layer that you create, in a frame numbered the same as where that button exists, you would add the event listener:
btn1.addEventListener(MouseEvent.CLICK, btn1Click);
Descriptively, that line of code contains the following:
buttonInstanceName . displayObjectMethod (eventClass . eventType, eventHandlerFunction);
The name of the unique function for processing the clicking of that button was already defined at the end of the event listener assignment, so now you just have to write that function out:
function btn1Click(evt:MouseEvent):void {
   // whatever processing you need to do
Here's some of what's involved there:
evt:MouseEvent - the event listeners throws an argument automatically which the function must be set up to receive.  In this case I have given that argument a variable name of evt, though I could have chosen anything.
:void - this defines the class of the value that the function will return.  In this case, the function does not return anything, so "void" is used.  If it did return a value, you would see a line containing "return xyz"; in the function (where xyz is not literal, it simply represents the variable or value being returned)
In AS3, in strict mode, it is necessary to identify the types/classes of the variables being created, which is why you see :String, :MouseEvent, :MovieClip, etc... showing up everywhere.
So you want to check a bunch of checkboxes.  The easiest way to accomodate that is to name them all similarly so that you can loop thru checking them (ex: cb1, cb2, cb3, etc).  If that wasn't conveneient, meaning you'd rather have their names indcate their purpose, then you could store the instance names in an array and use that to loop thru them.  And in your case, you say you want to check which ones are selected.  For the example below, I'll show the cb# version, building on the function I showed earlier.
function btn1Click(evt:MouseEvent):void {
     for(var i:uint=1; i<=numCBs; i++){
          if(this["cb"+i].selected){
               trace("cb"+i+" is selected");
Sorry for the lecture, but I figure with a background in programming, you might appreciate a little extra info and actually understand it.