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