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Hello again.

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In this lecture, we're going to be adding some variables so that we can play around with our numbers

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more easily and make our object change its behavior.

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So let's jump in and get started.

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So the problem we've got at the moment is that our car is going a fixed amount of speed and a fixed

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amount of rotation.

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What if we want to have pushed down the accelerator and go faster or slower or turn left or turn right?

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We can't do that at the moment.

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That's because we've got these numbers hardcoded into our method.

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Instead of doing that, we want to use variables and you can think of variables like boxes.

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They help us store, manipulate and refer to information.

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So for example, here I've got this box, it's called hit points and it has a value of 20 stored in

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it.

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At the moment, each variable has to have a name.

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The name here is hit points.

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Each variable contains data.

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Presently it's 20, it could be zero, it could be a million, and each variable is of a particular

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type.

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This is really important.

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The type here is whole numbers, and whole numbers are known as integers.

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So we would write this or declare this in our script as int.

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This is the type int as in integer and then the name hit points and we use a lowercase letter first

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of all like a lowercase h and then uppercase for any other words that follow.

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So hit points written like this equals 20 and then semicolon we put semicolon at the end of things to

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say we are done with this particular statement.

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So that is how we declare a variable.

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So declaring it as a variable called hit points of type int and also how we assign a value to that variable

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or define a variable.

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The hit points is currently equal to 20.

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In terms of types, there's a few common types that we'll use INT is for whole numbers, float is for

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fractional numbers up to six or seven decimal places, double is for fractional numbers up to 15 decimal

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places.

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To be honest, I don't really use double ever because for me six decimal places is usually plenty when

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it comes to the precision I need.

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But if you needed a ton more precision you might use a double bull is for a true or false variable.

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So if you want to say this is true, do a thing.

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Or if it's false, don't do a thing.

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Balls are very handy and string is when we wish to have a sequence of characters that we print out exactly

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as we've typed them in.

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And strings require quotation marks in order to say This is what we would need to create.

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So let's look at those examples a bit more specifically.

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If we wanted to create a float called speed, then we would type in float speed equals and then whatever

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the value we wanted it to be, in this case, 3.8 And as we've talked about before, if you are using

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a float and you have a decimal place in here, you need to put an F at the end of it mostly.

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So that unity knows, Oh, it's a float and not a double.

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We put the F at the end there and then with a bull we have the name is is alive equals true.

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So we could define it as true or as false.

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And then, for example, with a string, we once again start off with the type string and then we would

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give it a name here, give it my name and my name is Rick.

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And once again, using our box analogy, the box is called name and the information within that is Rick,

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which is just four characters, one after another in this particular sequence.

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So let's create ourselves a variable.

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Now, we need to put this in a specific spot.

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We want to put it within our class.

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These are all the things we're creating here within our class, but we put it above our start method,

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so we're declaring some variables right at the top here I'm going to declare a variable which would

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be of type float.

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It's going to be a float because I need decimal places and I will call this steer speed.

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I could call it steering speed or turn speed, any of those kind of things, but steer speed makes sense

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for me.

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Steer is what you do on the steering wheel and speed is obviously how fast we're going to turn or how

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fast we're going to steer and then equals and I will initialize this or in other words, give it the

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first value of the value that we've currently got down here at the moment, which is 0.1 F and then

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semicolon.

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Now what do we do?

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Well, we've got this steer speed variable.

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We pop that in here within our rotate method instead of using the actual value and type in steer speed.

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And just to reiterate, the reason we're doing this and not leaving that number in there is because

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we want to change steer speed based upon things that happen in our game.

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So sometimes this B will be 0.1 F, sometimes it'll be zero, sometimes it will be one, for example.

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So we need to be able to change this, which will do an upcoming lectures.

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But if we just have a hard coded number in there, we can't change it on the fly now, can we?

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Okay.

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So we've added steer speed and I've got a challenge for you to make sure that you're following along

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to create a variable called move speed and to use that variable in your transform translate method in

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a similar way to that which we've just done in our rotate method.

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So please pause a video, take on that challenge.

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See you back here when you're done.

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Rightio.

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So we will create ourselves a new variable which will be of type float as well and we'll call this move

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speed and that will equal whatever we're using down here at the moment, 0.01 F and this is just where

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we're initializing it.

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This can change.

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This is just saying what the starting point is.

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And then instead of having our numbers baked in down here, we're going to add move speed as our variable,

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save that up, jump back over into unity.

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Make sure this all worked as a starting point.

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We'll click on play.

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The behavior should be exactly the same.

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Yes, it is.

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Fantastic.

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Okay.

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And then we'll do one last thing just to make sure that all works.

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Instead of having steer speed at 0.1 F, let's make it say one F.

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Now, just a side note.

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When you've got a float and you've got a whole number, you could just not put the F there.

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And Unity will say, That's cool, I'm okay with that.

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No errors in this instance.

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Or you can put the F there and inside.

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That's fine as well.

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To be perfectly honest, sometimes I do an F, sometimes I don't do an F depending upon whether I forget

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or I'm paying attention.

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So it's good habit to put an F when you've got values that relate to float.

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So I'm going to leave the F in there.

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But sometimes you might see me accidentally not have the F just so you know, jump back over into unity,

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click on play.

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What should we expect to see here?

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Well, we should expect to see that our thing spins around a lot more quickly.

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Zoom, zoom, zoom.

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There we go.

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Still with the same forward but more turning per frame.

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So that's the behavior we get.

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In the next lecture, I'll show you a way to be able to change those values right here from within.

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Unity and not having to go back to your code each time if you want to change it.

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So I will see you in the next lecture.