04Robotics - Variables and Functions

8/9/2019 04Robotics - Variables and Functions

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Variables and Functions


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Open your Encoder program

Let’s begin by opening the “Labyrinth Auto

Straight” code.

Save this file as Labyrinth with variables.


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Making changes takes too much time

Suppose your auto straight program doesn’texactly work with the motor powers we

selected.

Change these as needed.

But you need to change these

everywhere. Is that practical?


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Behaviors and Variables

What if we could change the power

levels in ONE place and that would

change the power levels in ALL the

places at one time?


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Variables

You can take a motor power value and STORE it inside of a variable for later use.


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Variables


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Variable Types

These can be whole numbers only and are referenced by “int”.


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Variable Types

Referenced by “string” , these can be a combination of letters,

numbers, and spaces.


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Let’s use the “int” variable

When you name and “integer” type variable you cannot use:

•Spaces

•Characters(!)

•Numbers(1)

•Already reserved/recognized terms(int)


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Replace all motor speeds with integer “names”

Now change all motor powers tothe appropriate variable name.

Do this for the entire program.

Then save, compile, download,

and test.


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Test

The idea behind this is that you can now

“change” the motor powers in ONE place

instead of 12 places as you test. This is just

one way to program efficiently.


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Behaviors and FUNCTIONS


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FunctionsFunctions are pieces of code

that come BEFORE task main.

We use “void” to begin our

functions. The function itself is

then given a name, in this case

moveStraight. There is a set of

empty parenthesis after the

name. Then the commands are

placed inside the functions curly

braces.


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The “call”Then, when you are ready to

use the code, you simply “call”it from within task main.

So in summary, you first have

to DECLARE the function and

give it a name. Then you must

CALL the function to use it.


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Behaviors and FUNCTIONSOpen the file Labyrinth Auto Straight.

Save this file as Labyrinth with functions.

Declare the function and name it BEFORE task main.


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Highlight the code starting with

the FIRST IF statement and

END with the last IF statementRight click and select copy.

Make sure you DO NOT copy

the while loop’s curly braces.


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Then paste the code inside the

functions curly braces.


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Behaviors and FUNCTIONSDelete all instances of this “highlighted” code in your program and replace

each instance with the call.


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Let’s test your understanding

1. Create new FUNCTIONS for your right and leftturns.

2. Compile and test the program to see if it makes

it into the labyrinth.

3. If successful, use COMMENTS to EXPLAINeach line of code in YOUR own words.

4. Be sure to place your NAME in the comments

for grading.

Documents

04Robotics - Variables and Functions