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Arrays are used to store multiple bits of the same type of information in a single variable
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Arrays, you can store many objects
in a single variable, right?
0:00
So I could create different variables,
or I could make one variable, and
0:04
it could have multiple values then, okay?
0:07
The weirdest thing about arrays, and
0:10
this is crazy, you'll think it's crazy
when you first start playing with them,
0:12
and you'll do a lot of fail waves,
actually, from this problem.
0:15
Arrays start at zero, okay?
0:19
Normally, we're used to counting, we're
like, oh, number one, two, three, four.
0:20
Arrays start at zero, and
this is something that we do as humans.
0:24
I have a daughter who's not quite one yet.
0:28
So she's actually zero years old, and
if you ask me how old's your daughter,
0:31
I would never say zero years old.
0:35
I would likely say how many months she is.
0:36
I might say she is in her first year, so
0:39
it's her first year but
she is really zero.
0:41
So when you're talking about arrays and
your talking about the first element,
0:43
if you think of that, that kind of
helps me remember that zero we do that.
0:47
Like the zero, zero to one,
that's the first period there,
0:52
right, so that's the first element
in the raise the zero with.
0:55
We'll a look really quick at that.
0:58
And then arrays also let
you know how big they are.
1:00
Okay, so you can take a look at them.
1:03
So I am talking about this,
so we can walk through a for
1:05
loop really quick with arrays.
1:08
So this is kind of why
I am introducing it,
1:09
I don't want to focus too much
on understanding this, and
1:10
if you have questions about these
afterwards we can walk through those.
1:12
So, I thought we'd do a little
example with something that I
1:15
thought I knew the numbers of.
1:18
I thought the Jackson Five,
1:19
I thought there were five Jacksons, since
the title of the band is the Jackson Five.
1:20
[LAUGH] It turns out there's six,
which is weird.
1:24
You see when I create the array here,
there's brackets, and
1:27
that's saying that it's an array.
1:30
It's saying there's multiple of these
names stored in this one variable called
1:31
jacksons, and to get the first one,
the first element here is Michael.
1:35
And you can access that with the zero.
1:39
So you do bracket zero to get Michael out
and you do bracket two to get Tito out.
1:41
These are the best,
obviously the best of the Jacksons.
1:45
Then you can see that there were
six Jacksons of the Jackson 5.
1:50
Let's do a live coding example of
printing out the Jacksons, and
1:55
we'll use the old school for
loop that we talked about.
1:59
If we come over and
look at Jackson's Old School.
2:03
Here.
2:07
So, I've gone ahead and
built that example exactly.
2:11
So, I have this array.
2:13
That's sitting here.
2:14
Let's just go ahead and
say, the Jackson Five are.
2:15
All right, so let's do our for loop.
2:25
So I'm going to use this
i variable equals zero.
2:27
And while i is less than
the length of that array,
2:32
we're gonna loop through every single one
of those cuz that's gonna return that.
2:37
And then we're gonna say i plus plus.
2:41
Because we're going to increment and
the end there.
2:44
So we're going to move our i forward, and
then we're going to pull a Jackson out.
2:45
And we do that remember we reference
the array by the index, okay?
2:51
So this number is going to keep going up
and it's going to change each time, so
2:58
0 is going to pull up Michael.
3:02
For the second one,
this one's gonna pull up Tito,
3:05
and it's gonna come through there, so
3:10
each iteration through there,
we're gonna say %s Jackson,
3:13
and do a new line, and
we're gonna push the Jackson through.
3:18
They've got a closing method there.
3:29
Any bugs?
3:33
Any bug spotters?
3:34
All right, so
let's see who these Jacksons were.
3:35
And this is the old school style, right?
3:38
So Jackson's old school.
3:42
See that I have the new school there is
why the tab completion is not working.
3:51
There they are.
3:57
So we got Michael, Jackie, Tito,
Germaine, Marlon and Randy.
3:58
And there was a little bit of overlap.
4:01
I think what happened is somebody hit
puberty and then they popped them out and
4:02
put a new, younger kid in there
just to keep the pitch right.
4:06
It was probably like a pitch
problem is my guess.
4:09
But there was a time when there
was six of them on stage,
4:11
which is just out of this world.
4:13
So this is the old school version, right?
4:15
So this happens all the time.
4:17
You're going to to look on Stack Overflow.
4:18
You're going to see this.
4:19
You're going to see this pattern.
4:20
It's not the way you should do it.
4:21
Java gives you a newer way to do this.
4:24
But you're going to see this out there and
you're going to see this elsewhere.
4:26
You're going to see this in other
programming languages as well.
4:28
If you're looping through something that
you know, you're gonna use all of them.
4:30
You don't want to build
a statement like that, right?
4:33
Then again, cuz you want people to come
in and understand what your code's doing.
4:36
You don't want people to come in and
not know what that for loop is, and
4:39
just think that that's how it works.
4:42
Chris, you look like you have a question.
4:45
Something about the variable,
I thought you were saying.
4:48
>> I was thinking about that.
4:51
>> Yeah?
>> [LAUGH]
4:53
>> And you keep using the variable i.
4:55
>> Yeah?
4:59
>> Where does that come from?
4:59
>> Oh, you know what,
that's interesting, Chris.
5:00
Thanks for asking that question.
5:02
I'm using that because that's
the standard here, but, as we know,
5:05
that's probably a bad variable name,
right?
5:10
Like, what is i?
5:12
Are you talking about yourself?
5:13
Is that me?
5:14
No.
5:15
It's traditionally probably for index.
5:16
However, what happened
is you can nest loops.
5:19
So what happens if there's another for
loop in here, what do you use?
5:22
What's the next loop?
5:25
Oh, you use j.
5:26
Why do you use j?
5:27
I don't know.
5:28
So this is probably bad practice that's
been baked in to everything, right?
5:29
So if you really wanna keep track
of an index, maybe call it index.
5:34
Right?
5:39
So that's, but I used i because I wanted
to show you, and thank you Chris for
5:39
asking and pointing that out,
because I would have totally forgotten.
5:43
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