Animated Ball Tutorial AS3 - Assistance

[David_111]

Hello Friends,

I wonder if someone might be able to spot what I am doing wrong in my code.
I am trying to follow and create a tutorial which explains how to make a bouncing ball.

I am really struggling with the Action Script 3.0 even though the teacher types it in.
I am inserting the code so that you can view it.

Many thanks in advance if anyone has an idea where I might be going wrong.
I am very grateful for any and all advice.

The tutorial is located:
http://www.youtube.com/watch?v=36BIN9OKNf8

My code is:

var gravity:Number = 3
var speed:Number = 0
var position:Number
var num:Number =350

addEventListener (Event.ENTER_FRAME, animation)
function animation(e:Event) : void {
speed+=gravity
position = ball.y+speed
if (position>num) (
ball.y = num
);speed = - speed=0.8;
} else {
ball.y += speed;
}

[Nig 13]

Several mistakes:

var gravity:Number = 3
var speed:Number = 0
var position:Number 
var num:Number =350

addEventListener (Event.ENTER_FRAME, animation)
function animation(e:Event) : void {
    speed+=gravity;
    position = ball.y+speed;
    if (ball.y>num){
        ball.y = num;
        speed = -speed*0.8;
    } else {
        ball.y += speed;
    }
}

[David_111]

Hello Nig 13,

Thank you very kindly. You have helped me out again!
I am trying to learn as I go along but I have to thank you and the others on FLASHKIT Support who really help those of us with the learning.

I truly appreciate all the assistance very much.
Thank you again for your help, your time and your expertise!

[Nig 13]

No problem, but allow me to point out the errors to help you:

- you should always have semi-colon at the end of a code line to signify its end, like this:

var gravity:Number = 3;
var speed:Number = 0;
var position:Number;
var num:Number =350;

this is crucial as it can sometimes cause errors without you knowing it, but it basically tells the code to stop there and not mix with anything in the lines below, because something like this works:

var myVar = 
5;

trace(myVar);

The code isn't stopped in the first line, but continues in the second line and sets its value as 5, and then the semi-colon stops it, but you don't want this to give you errors, right?

- if statement looks like this,

if(condition){
     // do stuff
}

with curly brackets {} and not simple brackets ()

- always tidy your code to make it easier for yourself to spot the errors easily. This is a good example of a bad structure:

function animation(e:Event) : void {
speed+=gravity
position = ball.y+speed
if (position>num) (
ball.y = num
);speed = - speed=0.8;
} else {
ball.y += speed;
}

it's really hard to tell what's what, and what's happening and stuff like that. Remember that anything, a function for instance, which starts with { needs to be closed with a }, and I'd tidy the code like this:

function animation(e:Event) : void {
     speed += gravity;
     position = ball.y+speed;
     if (position>num) {
          ball.y = num;
          // I have no idea what the code below does, 'cause it's wrong in every possible way, you can't have two equals signs like that
          speed = -speed=0.8;
     } else {
          ball.y += speed;
     }
}

now I know where the if statement ends, and where the function ends to easily distinguish between them, and the variables

Hope this helps