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You already learned about using variables [br]to store numbers or strings.

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Now we're going to learn [br]about something called arrays,

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which let us store multiple items [br]in just one variable.

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As you'll see, arrays let us do [br]all kinds of useful things.

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Okay, let's review variables. All right?

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So we have, <i>var myFriend = "Sophia"</i>.

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So, a variable is just a way [br]of storing a value, like Sofia,

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and giving it a label so our program [br]has an easy way to refer to it later.

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We can think of it like a drawer,

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with a <i>myFriend</i> label on the outside [br]and Sofia on the inside.

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So whenever we look inside it, [br]we find Sofia.

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Now, sometimes we want to hold [br]multiple values in a single variable

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and we can't just do it like this[br]because we'll get a syntax error

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and our program will freak out,[br]and all that stuff.

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So we have a specific way[br]that we do that,

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and that's using arrays.

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So we could say, <i>myFriends = </i>,

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and then we have to do [br]a square bracket,

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and then inside, [br]that's where we can put all the values.

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So we say, Sofia, [br]and we have John, and we have Leif.

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All right, so those are my three friends.

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Maybe in order of how much I like them, [br]but don't tell them that.

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Okay, so now our variable [br]holds three values, not just one.

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And we can imagine [br]it's like a chest of drawers,

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and we put this label, <i>myFriends</i>, [br]on the whole chest.

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And we can just open the right drawer

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to find the value [br]we're looking for, right?

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And you imagine, with a chest of drawers,

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if you want to know [br]what's inside the first drawer,

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you would just open it up and look inside.

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So how do we do that with our array?

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Well, we can just type [br]the name of the array,

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and then the brackets again--

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ooh, I misspelled it--

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and then the number [br]of whatever it is in the array, right?

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So maybe it would be 1. Okay?

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So, let's actually try this out

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by using the text command [br]and showing Sofia on the canvas.

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So we say, <i>myFriends</i>--[br]ooh, friend is a hard word to spell, huh?

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So, <i>myFriends[1]</i>,[br]and then we put it here.

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Oh, and then let's put a little fill.

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Oh, okay, so we see John. [br]Why do we see John?

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We said 1 for the element index, right?

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The 1 right here.

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Well, that's because [br]arrays start at 0, not 1,

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and it'll definitely seem weird at first,[br]but you'll get used to it.

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So if we put 0, [br]then we see Sofia, all right?

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And then, if we want to show [br]the next element,

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then we use 1, all right?

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So, and then if we want to do [br]the final element,

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the third element, then we use 2.

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So you just think to yourself:[br]"Okay, which one do I want to retrieve?"--

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Oh, let's spread these out--

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and where is it located, [br]and you just subtract one.

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So the first one is 0, [br]the second one is 1,

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the third one is 2, et cetera, et cetera.

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What happens if I forgot, [br]and I try to access Leif this way?

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Well then, we say <i>myFriends[3]</i>, [br]and we'll just get nothing.

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That's because there's nothing there, right?

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When it says 3, [br]it looks for the fourth element,

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and there's no fourth element,[br]so there's just nothing.

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And that's something that can happen a lot[br]when you're using arrays,

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so just look out for that.

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And the same thing [br]if I tried to access a hundred

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because I don't have a hundred friends, [br]I only have three,

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so then we get nothing, all right? [br]So let's get rid of those.

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Now, let's say we want to keep track [br]of how many friends we have

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because I'm really proud,[br]and I have three friends,

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and I want to let everybody know.

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So I'm going to go [br]and declare this to the world.

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So, <i>"I have " + numFriends + " friends!!!"</i>.

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Woo, all right.

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Okay, so I have three friends. Yay![br]Oh, that's not very many.

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Okay, so maybe Winston feels bad for me [br]and says he'll be my friend,

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and he says I can add him to the array.

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And I was like:[br]"Okay, cool. Thanks, Winston."

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So I add Winston.

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Oh, but it still says [br]I have three friends, right,

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because I have to go [br]and update this variable here.

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That means, every time [br]that I add something to this array,

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I have to update this variable, [br]and that could get really annoying,

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especially if all of you guys [br]watching this

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decide you'll be my friend.

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And then, you know, [br]I'm updating this thousands of times

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and having to update this every time.

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So here's the thing:

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We, so often, want to know [br]how long our array is,

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that there's a special way to do that.

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So the array will keep track [br]of how long it is

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using a property called <i>length</i>.

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And to use it, we just say, [br]<i>myFriends.length</i>,

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and then we'll get back the length.

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See, now it says 4, [br]and I can delete this variable.

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I don't need it any more.

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And this property will update [br]whenever we add.

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So maybe OhNoes Guy!! [br]says he'll be my friend, and I'm like:

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"Okay, you're kind of mean, [br]but okay, you'll be my friend."

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And we can keep adding[br]and it'll keep updating.

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So, that's really cool because, you know,

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it's a lot less work to keep track [br]of how long our array is.

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All right, so pretty much,

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whenever you want to store [br]a list of values like this,

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we'll use an array.

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So keep watching to find out [br]all the really cool things

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that we can use them for.