Limit numbers on display for flash actionscript 3 calculator!!

Question

hello everyone
im making a flash calculator and ive nearly finished ive got one last thing i need to do and thats limit the amount of numbers i can enter to 10
this is my code so far and im struggling on this last part any help would be appreciated
var numbers:Array = [num0_btn,num1_btn,num2_btn,num3_btn,num4_btn,num5_btn,num6_btn,num7_btn,num8_btn,num9_bt n];
var operators:Array = [divide_btn,add_btn,subtract_btn,multiply_btn,equal_btn];
var op:String;
var num1:Number;
var num2:Number;
function addListeners():void
          for(var i:uint = 0; i < numbers.length; i++)
                    numbers[i].addEventListener(MouseEvent.CLICK, pressNumber);
          for(i = 0; i < operators.length; i++)
                    operators[i].addEventListener(MouseEvent.CLICK, pressOperator);
          clear_btn.addEventListener(MouseEvent.CLICK, clearAll);
          dot_btn.addEventListener(MouseEvent.CLICK, addDot);
          back_btn.addEventListener(MouseEvent.CLICK, backSpace);
function pressNumber(event:MouseEvent):void
          var instanceName:String = event.target.name;
          var numPushed:String = instanceName.charAt(3);
          if(window_txt.text == "0" || num1 == Number(window_txt.text))
                    window_txt.text = "";
          window_txt.appendText(numPushed);
function pressOperator(event:MouseEvent):void
          var instanceName:String = event.target.name;
          var currentOp:String = instanceName.slice(0, instanceName.indexOf("_"));
          if(!num1)
                    num1 = Number(window_txt.text);
                    op = currentOp;
          else if(!num2)
                    num2 = Number(window_txt.text);
                    showCalculation();
                    op = currentOp;
function clearAll(event:MouseEvent):void
          window_txt.text = "0";
          num1 = NaN;
          num2 = NaN;
function addDot(event:MouseEvent):void
          if(num1 == Number(window_txt.text))
                    window_txt.text = "0";
          if(window_txt.text.indexOf(".") == -1)
                    window_txt.appendText(".");
function backSpace(event:MouseEvent):void
    window_txt.text = window_txt.text.substring(0, window_txt.text.length-1);
function showCalculation():void
var dividedZero:Boolean;
switch(op)
case "multiply" :
num1 *= num2;
break;
case "divide" :
if(num2 != 0) {
    num1 /= num2;
}else{
     window_txt.text = "cannot divide by zero";
     dividedZero = true;
break;
case "add" :
num1 += num2;
break;
case "subtract" :
num1 -= num2;
break;
default :
break;
if(!dividedZero){
   window_txt.text = String(num1);
num2 = NaN;
addListeners();

Answer 1

Like most properties, you just assign it to the Textfield, as in...
yourTextField.maxChars = 10;
As far as tips go... you should spend time learning how to use the Help documentation provided for Flash.  One key thing to realize is that most classes of objects all have the same sets of elements making them up... properties, methods, and events.  The help documents define each one of them, including those that classes inherit from other classes.
So when I said you could use the maxChars property, all you should need to do is look up the maxChars property in the TextField class section of the help documents to see how it works.
And when you get better at using the help docs, you'll realize you didn't need to ask because the first place you look when you want to know about a class is to review its properties, methods, and/or events in the help documents