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Do While Loops
4:21Do While loops are a post-check looping construct, they will run at least once.
All right, so.
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While loop.
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We checked before hand, right?
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I wouldn't of had to keep on asking that,
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wouldn't have keep on doing that
loop if I didn't ask for it.
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Now let's do a do while loop, okay.
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So a do while loop.
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It's the same concept, right.
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We don't know how many times
it's going to happen but
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we do know that we want
it to happen one time.
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Right, so
it does what's called a post check.
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So this is useful when you want to
make sure that one time it happens.
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So.
The example that I have for this,
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we're totally shifting examples here.
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The example that I have for this one,
this pseudo code is Mini-Golf, right?
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So, you can't get a hole in zero.
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You have to get a hole in one, right?
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That's the best you can do.
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So you gotta putt once, okay?
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So we're gonna say do.
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Where, is the ball in the hole
is a Boolean over here.
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I should've said, is the ball in the hole?
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See, I'm bad at pseduo-code.
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And we do puttPutt.
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We're gonna call and
see if we hit that ball in the hole and
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until here, that's actually, while not.
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Right?
In English, too, if you wanted to say,
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until something happens, you're really
saying, wow, this isn't happening.
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Right?
So, until is a verb, or a whatever
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type of word that is in other programming
languages is a keyword in other type of
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programming languages, and it really means
while not, but Java does not have that.
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So we're gonna do, well, let's code it.
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So cross your fingers for me, here we go.
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Some more live code.
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All right.
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So, mini golf.
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All right, so I imported something that
we probably have not talked on yet.
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It's handy for testing and
example things like this.
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It's randomness, right.
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It's gonna allow us the ability
to give a 50/50 thing, right.
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So I don't know about you but
my mini golf skills is not 50/50,
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I usually have about 99, you know I
take a very long time to go through.
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So what we'll do is we want one time,
we want to do a putt putt.
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And let's keep track of it so
that we can see how bad we did.
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Or how bad the computer did,
actually, right?
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So we're gonna do numberOfPutts.
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Such a weird word, you know, how like
when you're typing words and you're like,
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is that really how you spell putt?
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I don't know.
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And putts, too, like.
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All right.
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So, boolean ballInHole is gonna be false.
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We're gonna start out with it false,
right?
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So the do while loop,
we're gonna say do while, and
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this is where we're doing the end tells,
so not the ballInHole, right?
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So it's a little strange, right?
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So you're thinking,
while the ball isn't in the hole,
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while that's not true,
keep on looping, okay?
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Let's just print out something so
we know that we're put that's not great.
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Alright.
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So let's use that random generator.
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And I called that thing luck,
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I called the variable luck, which is what
you need when you're doing this stuff.
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And it has random has
the opportunity to return numbers or
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other random things, one of the things
that can return is a Boolean.
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And remember, Booleans are true or false.
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We're setting ballInHole to the Boolean,
so therefore when it comes to check,
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we'll see, we want to increment.
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I don't know if everybody knows
what this incrementing is or
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if we remember what that is.
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What it does is it basically is shorthand
for saying, I could say number of putts
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equals what number of putts was plus one.
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So it just takes whatever's in there and
adds one to it.
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It's a shorthand.
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Let's keep it in there.
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We're gonna talk about that
a little bit later, too.
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All right.
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For sure one time it goes through.
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It will at least be one, right?
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Cuz they tried one time.
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And if the ball went in the hole,
it would be over, and good job,
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we did a hole in one.
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But we'll say, you got it in %d,
because it's a number.
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And we're gonna pass n
the number of putts.
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What do you say?
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I remember that.
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Let's do it.
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I don't know where my history went.
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Let's see.
So we'll call this Minigolf.
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We're gonna compile Minigolf, and
then we are going to run Minigolf.
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Don't put the Java extension there.
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One, hole in one, we did it randomly.
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We randomly did a hole in one!
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>> [APPLAUSE]
>> Yeah!
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Still, a hole in one.
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Come on, oh there it is.
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Three putts.
This should.
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Wow, it's doing pretty good.
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>> Looks good.
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>> There's two putts.
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Yeah.
>> [LAUGH]
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>> Yeah.
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Let's go golfing and
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let's put some money on it.
Cool.
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>> [LAUGH]
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