Hello World!
I'm talking about the scope of variables in Alice3.
The scope refers to where in the program
the variable is available.
String message is declared outside any block.
It5's available anywhere in my first method.
Double [speed] however, is declared inside this for loop.
And is only available inside this loop.
Let's run this and see what we have.
And he says, "Greetings earthlings."
And then he says, "Welcome to Mars."
So here's what I did:
The string messages given initial value of "Greetings earthlings."
Inside the loop,
we change the message to "Welcome to Mars."
This loop goes twice.
So the first time,
the message is "Greetings earthlings."
that changes to "Welcome to Mars."
So on the second iteration of the loop,
when he says the message he says "Welcome to Mars."
If I move this variable message
to inside the loop it is reset
to "Greetings earthlings" each time through the loop.
So when we run this he says "Greetings earthlings"  twice.
Ok, let's move that back
and make it so that it's anywhere inside my first method.
The variable double speed has a value of 1,
and that's the duration I'm going to use so it's speed.
speed is set to 10 here,
so he should say welcome to Mars for a very long time.
But if we run it, you can say he doesn't say that any longer than before.
if I move this up here,
and make it so that scope is
all of my first method,
changing speed to 10 here
will make him say the second message
much longer, so let's run that is to see.
And welcome to Mars stays up there for a very long time.
Let me put it inside this do together.
If I tried to change speed to 10 here
It doesn't know that [speed].
Let's get rid of that, put that in the trash.
And have the aliens say something here.
And maybe just say "hello"
and I'm going to add the duration
of .25, that's really fast.
and I go back and I don't have any variables
that are available for that.
If I move speed
up, so that it scope is anywhere in the for loop,
then when he says hello,
I have the option of picking speed from that list.
So, let's run that:
"Greetings earthlings", "hello",
"Welcome to Mars", "hello" that's it.
So you can play with that and see
where the scope is.
if I put this in this do together,
and it's not even available here.
If I try to use speed, I can't do that.
Alright, that's it for now.