AS3 keyboard animated character - Compiler errors all over the place despite following tutorial to the letter - actionscript-3

Question

Trying to create a 2D character that responds to keyboard inputs in Flash Professional CC. Every YouTube tutorial my son and I have tried produces Compiler errors and NOTHING works.
import flash.events.KeyboardEvent;
import flash.events.Event;
var rightKeyIsDown:Boolean = false;
var leftKeyIsDown:Boolean = false;
var upKeyIsDown:Boolean = false;
var downKeyIsDown:Boolean = false;
var playerSpeed:int = 7;
stage.addEventListener(KeyboardEvent.KEY_DOWN, pressAKey);
stage.addEventListener(KeyboardEvent.KEY_UP, releaseAKey);
function pressAKey(event:KeyboardEvent):void
{
if(event.keyCode == Keyboard.RIGHT)
{
rightKeyIsDown = true;
}
if(event.keyCode == Keyboard.LEFT)
{
leftKeyIsDown = true;
}
if(event.keyCode == Keyboard.UP)
{
upKeyIsDown = true;
}
if(event.keyCode == Keyboard.DOWN)
{
downKeyIsDown = true;
}
}
function releaseAKey(event.KeyboardEvent):void
{
if(event.keyCode == Keyboard.RIGHT)
{
rightKeyIsDown = false;
}
if(event.keyCode == Keyboard.LEFT)
{
leftKeyIsDown = false;
}
if(event.keyCode == Keyboard.UP)
{
upKeyIsDown = false;
}
if(event.keyCode == Keyboard.DOWN)
{
downKeyIsDown = false;
}
}
player_mc.addEventListener(Event.ENTER_FRAME, moveThePlayer);
function moveThePlayer(event:Event):void
{
if(rightKeyIsDown == true)
{
player_mc.x += playerSpeed;
}
if(leftKeyIsDown == true)
{
player_mc.x -+ playerSpeed;
}
}
What is wrong with the above code? We have followed this tutorial, which seems very straightforward however the minute we type in a curly bracket it highlights in red, and then when we try to test we receive Compiler Errors.
Scene 1, Layer 'Player', Frame 1, Line 35, Column 27 1084: Syntax error: expecting rightparen before dot.
We are using Flash Professional CC and AS3 - is there a better resource for tutorials for this type of thing as we're being driven mad having tried at least 5 of these now without success.
Would really appreciate some advice on why the above is wrong and also where we might find tutorials that actually work!
Thank you.
NJ & Son! :)

Answer 1

I threw your code into Flash and did not see any issues surrounding mismatching parenthesis; however, I did notice the following errors
First, In the following if control structure:
if(leftKeyIsDown == true)
{
player_mc.x -+ playerSpeed;
}
You are attempting to use an operator of -+ but no such operator exists in Flash ActionScript. I'm thinking you meant to do the following instead:
if(leftKeyIsDown == true)
{
player_mc.x -= playerSpeed;
}
Second, the issue is right here:
function releaseAKey(event.KeyboardEvent):void
{
// your code
}
You need a : to specify the datatype. Can't believe I missed that. So it should be:
function releaseAKey(event:KeyboardEvent):void
{
// your code
}
I was able to plug this code into Flash CC and get it to compile with no errors. Cheers!