Error using Arrays

[brendenc14282108]

I am trying to use Array to count my boxMC. my boxMC is on my background of WorldMC. Its saying that my line of

"for (var count=0; count<boxMC.length; count++){

     boxMC[count].update();

}"

Has no default value

Here is my error:

ReferenceError: Error #1069: Property update not found on tankscript.turrent.Box and there is no default value.

var boxMC:Array;

  boxMC = new Array();

  //------------------------------

  // -----Box Spawning------------

  //------------------------------

  //only spawn a box if there are less tan 100 already on screen

  while(WorldMC.numChildren<10)

  {

  // Make a new instance of the box class

  var bx = new Box();

  // add the box to the display list

  WorldMC.addChild(bx);

  //position and rotate the Box;

  bx.x = Math.random() * -1100;

  bx.y = Math.random() * 1;

  bx.rotation = 40;

  // add the box to list of box

  boxMC.push(bx);

  }

  for (var count=0; count<boxMC.length; count++){

  boxMC[count].update();

  }

}

[kglad]

if that error message is related to the code you showed (which is not clear because the error contains a typo), either you don't have an update() method defined for your array members, or you do and you need to explicitly cast them as the class type that has a well-defined update method.

eg, in your Box class, if you have an update method defined, use:

Box(boxMC[count]).update();

[brendenc14282108]

Yes sorry i do have a Box class. in which the update(); goes to. I tried your code you gave me and it came back with:

1195: Attempted access of inaccessible method update through a reference with static type tankscript.turrent:Box.

Would it help more if i showed my Box class code?

[Colin Holgate]

Make sure the update function is public and not private.

[brendenc14282108]

hm.. I did so, i do not got the error of no default value now.  but my boxMC do not seem to like to update and move now. i used the code of kglad suggested too

Heres the Box class:

package tankscript.turrent

{

  // import any necessary files/libaries

  import flash.display.MovieClip;

  import flash.events.Event;

  import flash.geom.Point;

  public class Box extends MovieClip

  {

  private var boxSpeed:int;

  private var target:Point;

  public function Box()

  {

  // constructor code

  boxSpeed = 10;

  trace("Made a Box!");

  //Set target location of the ship

  target = new Point();

  target.x = Math.random() * 2500;

  target.y = Math.random() * 0;

  // add an event listener  to update every frame

  //addEventListener(Event.ENTER_FRAME, update);

  }

  public function update()

  {

  // point the box at the target

  var dx = target.x - x;

  var dy = target.y - y;

  var angle = Math.atan2(dy,dx) / Math.PI * 180;

  rotation = angle;

  // move in direction of the box is facing

  x=x+Math.cos(rotation/180*Math.PI)*boxSpeed;

  y=y+Math.sin(rotation/180*Math.PI)*boxSpeed;

  // Calculate the distance to target

  var hyp = Math.sqrt((dx*dx)+(dy*dy));

  // if the hyp is less than 5 pixels, pick a new target

  if (hyp <5)

  {

  target.x = Math.random() * 2500;

  target.y = Math.random() * 0;

  }

  }

  }

}

[kglad]

there's no loop so all you're going to see is a one-time rotation change and x,y change.

[brendenc14282108]

then how would i get a loop? im a beginner in coding and im following a video and just changing the objects to match what i like.

[kglad]

you could use:

package tankscript.turrent

{

  // import any necessary files/libaries

  import flash.display.MovieClip;

  import flash.events.Event;

  import flash.geom.Point;

  public class Box extends MovieClip

  {

  private var boxSpeed:int;

  private var target:Point;

  public function Box()

  {

  // constructor code

  boxSpeed = 10;

  trace("Made a Box!");

  //Set target location of the ship

  target = new Point();

  target.x = Math.random() * 2500;

  target.y = Math.random() * 0;

  // add an event listener  to update every frame

  //addEventListener(Event.ENTER_FRAME, update);

  }

public function startUpdate():void{

addEventListener(Event.ENTER_FRAME, update);

}

public function endUpdate():void{

removeEventListener(Event.ENTER_FRAME, update);

}

  private function update()

  {

  // point the box at the target

  var dx = target.x - x;

  var dy = target.y - y;

  var angle = Math.atan2(dy,dx) / Math.PI * 180;

  rotation = angle;

  // move in direction of the box is facing

  x=x+Math.cos(rotation/180*Math.PI)*boxSpeed;

  y=y+Math.sin(rotation/180*Math.PI)*boxSpeed;

  // Calculate the distance to target

var hyp = (dx*dx)+(dy*dy);

  // if the hyp is less than 5 pixels, pick a new target

  if (hyp <25)

  {

  target.x = Math.random() * 2500;

  target.y = Math.random() * 0;

  }

  }

  }

}

[brendenc14282108]

With the code you gave me i tried it but with "private function update" private it cant find the update with the code of "Box(boxMC[count]).update();" but when i  change the function to public it doesn't give me any errors but my boxMC do not move still.

[Colin Holgate]

The orginal code for Box had an enterframe listener, so that it moved itself along. You disabled that and tried to call update() from your other code. But you only call it once, instead of every frame. That's why it doesn't move.

kglad's approach was a mixture of how the code originally was, and with the ability to start or stop the animation. update() is only called from within the class, whcih is why it can be private.

To set things moving you would call the startUpdate() function, and to stop them moving you call the endUpdate() function. In your other code that would be like this:

for (var count=0; count<boxMC.length; count++){

  boxMC[count].startUpdate();

  }

[brendenc14282108]

ah okay i see now, but now when i call startUpdate it now says

"ArgumentError: Error #1063: Argument count mismatch on tankscript.turrent::Box/update(). Expected 0, got 1."

Will the code change since my boxMC in inside of my WorldMC?

[Colin Holgate]

That's a mistake in kglad's code. Change this:

  private function update()

to:

  private function update(e:Event)

[brendenc14282108]

This code now comes with no errors, but 1 out of my 10 children that spawned do not move now

[brendenc14282108]

Also how does the

"for (var count=0; count<boxMC.length; count++){

  boxMC[count].startUpdate();

  }"

What is this telling me that its doing? Do i need to change it since my boxMC is inside another object? Because my background is WorldMC and that is where i have my boxMC spawning to.

[kglad]

does that mean 9 out of 10 do move?

and use the trace function to debug your code: http://forums.adobe.com/docs/DOC-2572

[brendenc14282108]

yes sorry 9 out of 10 move

[kglad]

use the trace function to determine which fails to have startUpdate() applied.

[Colin Holgate]

boxMC is an array, not a display object. Its values are a list of movieclips, which happen to be inside WorldMC, but that doesn't matter. The code is correct.

Are you sure that your WorldMC is completely empty at the start? If you already had a single example box in there as a test, it won't be in the array.

[brendenc14282108]

oh okay, well i just moved it higher off screen so it will be fine with it not moving then. Thank you

[brendenc14282108]

With the video that im watching he is able to update the Box class using the code of

"for (var count=0; count<boxMC.length; count++){

  boxMC[count].startUpdate();

  }"

He also does not have the (e:Event) too. hes able to do it with leaving it such as "private function update()" is there something obvious i'm missing? i seem to do that a lot..

i have tried using public and private function with out the "(e:Event)" it tells me

"ArgumentError: Error #1063: Argument count mismatch on tankscript.turrent::Box/update(). Expected 0, got 1."

private function update(e:Event)

  {

  // point the box at the target

  var dx = target.x - x;

  var dy = target.y - y;

  var angle = Math.atan2(dy,dx) / Math.PI * 180;

  rotation = angle;

  // move in direction of the box is facing

  x=x+Math.cos(rotation/180*Math.PI)*boxSpeed;

  y=y+Math.sin(rotation/180*Math.PI)*boxSpeed;

[kglad]

are you conflating your corrected code from this forum and someone else code?

[Colin Holgate]

The startUpdate() function won't need the e:Event part.

Do you have the URL of the video that you're watching? That way you could say to us "take a look at 3 minutes 23 seconds, what does that bit mean?".

[brendenc14282108]

Game Development in AS3 Part 6 - For Loops - YouTube

at about 9:20

[Colin Holgate]

If you were to go all the way back to your first post, that's like the video told you to do. But the ships didn't update because you had missed the loop enterframe listener.

If you click this link, and press pause when you get there:

Game Development in AS3 Part 6 - For Loops - YouTube

you can see line 17 sets up the enterframe listener,  and the code you've been trying should be in a function, which he calls 'loop' in his example. Look at line 22 to see where that is set up.

One unusual thing is that he doesn't use public anywhere, he just says function, which I guess defaults to being public. That does add to the confusion.

[brendenc14282108]

okay, i did add the "function loop(e:Event)" but is there anyway to get the new code of kglad of "startUpdate" to work without the "(e:Event)" inside the Box class on this code right below here? As you can see in the video he was able to just do "function update()"

private function update(e:Event)

  {

  // point the box at the target

  var dx = target.x - x;

  var dy = target.y - y;

  var angle = Math.atan2(dy,dx) / Math.PI * 180;

  rotation = angle;

  // move in direction of the box is facing

  x=x+Math.cos(rotation/180*Math.PI)*boxSpeed;

  y=y+Math.sin(rotation/180*Math.PI)*boxSpeed;