ActionScript 3：将字符串转换为and运算符？

Question

I'm trying to create a simple calculator program in ActionScript for a school project, and I'm struggling to find a concise way to take an equation from an array such as this: "4","+","2"; and manipulate it so that the answer to the equation can be deduced. The problem is taking the String "+" from the equation array and turning it into a usable operator. At the moment, when an operator button is pressed on the calculator GUI it adds the operator to the equation array as a String (ie pressing the '÷' button will add "/" to the equation array).

I looked for an answer to this on Google and found something about a JavaScript function that I used in the code below (in lines 1 and 4), but all I end up with in the Output feed is "null", or "0" depending on whether I changed the variable 'answer' to a String, or a Number.

Here's the code I have so far:

import flash.external.ExternalInterface;

var equationArray:Array = new Array("4","+","2");
var answer:Number = ExternalInterface.call("eval",equationArray[0] + equationArray[1] + equationArray[2]);
trace(answer);

I'd prefer to use something like this rather than writing a long if statement to pick between different operators if that's possible. Thanks for the help!

Answer 1

I did some research and realized that your code doesn't work only in Chrome. There is an error

SecurityError: Error #2060
   at flash.external::ExternalInterface$/call()
   at FlexTemp/preinitializeHandler()
   at FlexTemp/___FlexTemp_Application1_preinitialize()
   at flash.events::EventDispatcher/dispatchEvent()
   at mx.core::UIComponent/dispatchEvent()
   at mx.core::UIComponent/initialize()
   at spark.components::Application/initialize()
   at FlexTemp/initialize()
   at mx.managers.systemClasses::ChildManager/childAdded()
   at mx.managers.systemClasses::ChildManager/initializeTopLevelWindow()
   at mx.managers::SystemManager/initializeTopLevelWindow()
   at mx.managers::SystemManager/http://www.adobe.com/2006/flex/mx/internal::kickOff()
   at mx.managers::SystemManager/http://www.adobe.com/2006/flex/mx/internal::preloader_completeHandler()
   at flash.events::EventDispatcher/dispatchEvent()
   at mx.preloaders::Preloader/timerHandler()
   at flash.utils::Timer/tick()

but if I switch of PepperFlash\\14.0.0.145\\pepflashplayer.dll in chrome://plugins/

all works fine. I think there are some problems with pepflashplayer.dll

Answer 2

In your flash file:

import flash.external.ExternalInterface;
import flash.text.TextField;
var equationArray:Array = new Array("4","-","8");
var answer:Number = ExternalInterface.call("myJsFunction",equationArray[0] , equationArray[1] , equationArray[2])
var tf:TextField = new TextField();
addChild(tf as TextField);
tf.text = answer.toString();

In the HTML page (into the ):

    <script type="text/javascript">
        function myJsFunction(arg1,arg2,arg3){
            return eval(arg1+arg2+arg3);
        }
    </script>

Is this what you try to do? Using eval like in your code I didn't get the correct answer. When you run as here above on localhost/server this will give you the answer.