Team 302 Software Training

C# Programming

Activity 0

1. Log onto the computer
2. Get a thumb drive
3. In the VSCodePortable run VSCodePortable.exe
4. Then use File -> Open Folder to open the Workspace on the thumb drive

C# Programming

• Text case and Spaces
• Blank Lines, Comments and Executable Lines
• Variables
• Expressions
• Conditionals
• Classes/Subclasses/Objects
• Attributes/Methods
• Calling Methods

Text Case and Spaces

• Everything is case sensitive, so
• Abc is not the same as abc or as aBC, etc.
• Spaces also matter as abc is not the same as a bc
• Can be between things but not within things (e.g. variable names cannot have spaces, but spaces can be after the variable name and before the next operator).

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Hint: This will be one of the greatest sources of compile errors

Blank Lines

• Blank Lines
• Neither comments nor executable
• Help make the code more readable (with a reasonable number of blank lines)

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Comments

• Comments
• Used to document code; don’t document the obvious
• What are you trying to do, Algorithm details, etc.
• Block Comments start with /* and ends with a */ everything between is a comment
• Line comments start with // (goes to the end of that line)
• A line Comment that starts with another / (three slashes ///) generate documentation automatically

Hints:

• Can be written before the code (often helps to organize thoughts)
• Often beneficial when someone else needs to look at your code

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Activity 1

• Open DragonGamePad.cs
• How many line comments are there?
• Are any line comments on the same line as an executable lines?
• Are there any comments that create automatic documentation?
• How many block comments are there?
• How many blank lines are in the file?

Activity 2

• Open DragonGamePad.cs
• How many line comments are there?101
• Are any line comments on the same line as an executable lines?26
• Are there any comments that create automatic documentation?51
• How many block comments are there? 0
• How many blank lines are in the file?24

Executable lines

• Executable lines (everything else)
• Typically end with a semicolon (;)
• Blocks will start with a curly bracket { and end with a curly bracket }
• Don’t have semicolons on the lines themselves
• Executable lines inside do

Hints (common sources of compile errors):

• Forgetting the semicolon
• Missing the closing (ending) curly bracket }

​

​

Executable Lines

Executable lines can span multiple physical lines. For instance, these are the equivalent:

Abc = a + b +c;

Abc =

a +

b +

c;

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Activity 3

1. Open snippet.cs
2. Inside the curly brackets DriveWithJoysticks

public override void DriveWithJoysticks()

{

⇒ Look here

}

• Find 7 things that are wrong with the file that will make it not compile and fix them.

Hint: What are some of the common things that cause compile errors?

Variables

Defines a type and a name

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• Use descriptive names
• Descriptive variable names:
• Makes your code more understandable
• Means you won’t need a comment to tell someone what the variable means
• Makes it less likely that inadvertently change it
• Can initialize where it is defined or on a separate line (but always initialize)
• Format:

VariableType variableName = initialValue;

​

​

Common Variable Types

• int - integer value (number without a decimal point)
• float - number with a decimal point
• double - number with a decimal point (more accuracy)
• bool - true or false
• enum - short for enumerated list which is a fancy integer value where the values get names.

enum - enumerated list

• Default start is 0
• Each item can have a value, but typically doesn’t
• Useful for giving descriptive names to constant integer values
• Example:

enum MECHANISM_TYPE

{

UNKNOWN_MECHANISM = -1,

GRABBER,

LIFT,

CLIMBER,

SIDE_HANGER,

ACTIVE_GRABBER,

MAX_MECHANISM_TYPES

};

​

Variables - Examples

int loopCount = 1;

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float motorSpeed = 1.0;

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bool isButtonPressed = false;

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bool isGamePiecePresent = false;

​

float proportionalConstant;

proportionalConstant = 0.2;

​

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Math Expressions

“Sequence of operators and their operands for a computation”

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Assignment:

a = b;

a += b;

a -= b;

a *= b;

a /= b;

Increment / Decrement:

++a;

a++;

--a;

a--;

​

Arithmetic:

a = b + c;

a = b - c;

a = b * c;

a = b / c;

a = b % c;

Hints:

• Working with integer variables may not yield desired results (it might truncate because integer math is used)
• Before dividing you should ensure the denominator is not 0.0.

Activity 4

1. Open LimitValue.cs
2. Inside the curly brackets GetInRange

public static double GetInRange

(

double value, /// <I> - value to check

double minValue, /// <I> - minimum value for the range

double maxValue /// <I> - maximum value for the range

)

{

⇒ line goes here (after block comment)

}

3. Define and initialize a double variable named output
4. Based on the description what should be the initial value?

Variable Scope

• Visibility within curly brackets {} (including inner or sub curly brackets, but not outer curly brackets). So, below variables defined in 1, can be used in 2 and 3, but variables declared in 3 can only be used inside 3.

{ // 1

{ // 2

{ // 3

}

}

}

​

• Declaring a variable inside inner curly brackets {} creates another variable

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Constants and Literals

Things we use (typically initial values or right hand side of assignments):

• true / false
• Explicit numbers (e.g. 82, 3.14159)
• Explicit strings (e.g. “Front Left Motor”)

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Activity 5a

public void RunMethod()

{

If ( buttonPressed )

{

double value = 1.0;

}

value = 0.5; // this value is not declared and will have a compile error

}

​

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How can this be fixed?

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Activity 5b

public void RunMothod()

{

double value = 0.0;

if (buttonPressed)

{

double value = 1.0; // new variable, value not reset

}

else

{

value = 0.5; // changes the value from 0.0 to 0.5

}

}

​

How can this be fixed?

​

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Conditionals

• Controls flow of execution based on a comparison
• == (equals): returns true when left and right values are the same, otherwise returns false
• != (not equals): returns true when left and right values are not the same, otherwise returns false
• > (greater than): returns true if the left value is larger than the right value, otherwise returns false
• < (less than): returns true if the left value is smaller than the right value, otherwise returns false
• >= (greater than or equal to): returns true if the left value is larger than the right value or if they are equal, otherwise returns false
• <= (less than or equal to): returns true if the left value is smaller than the right value or if they are equal, otherwise returns false

Hint: Common mistake is to use = instead of ==

Conditionals - if, if/else, if/else if/else

• Evaluates the conditional executes the next block if it is true
• else if and else blocks only get evaluated if the previous ones are false
• Special case for booleans: conditionals don’t need an explicit conditional comparison (e.g. == true).
• Instead if( bool ) is true or if ( !bool) is false
• Compound conditionals
• && is and
• || is or
• () can be used for groupings

Hint: Try to avoid complex compound comparisons, it is easy to make a mistake.

Careful with 2 ifs next to each other without the else both get evaluated

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Conditionals - if

Examples:

if ( isButtonPressed )

{

}

if ( !isButtonPressed )

{

}

​

if (isButtonAPressed && isButtonBPressed )

{

}

​

Conditionals - if / else if / else

if ( loopCount < 5 )

{

speed = 0.5;

}

else if ( loopCount < 10 )

{

speed = 0.75;

}

else

{

speed = 0.0;

}

​

if ( loopCount < 5 )

{

speed = 0.5;

}

if ( loopCount < 10 )

{

speed = 0.75;

}

else

{

speed = 0.0;

}

​

What is the value of speed if loopCount is 3?

Activity 6

• Continue modifying TeleopControl.cs
• Find TODO: #1
• Create conditional statements to set output if he values are larger than the 1.0 or smaller than the -1.0

Conditionals - switch /case

• Compares for equal (integers or enumerated list items)
• Starts with the switch indicating what you are going to compare
• case for each comparison value
• default for other cases
• Use a break at the end of each case to avoid running into the next case.

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Hint: Always have a default case.

Conditionals - switch / case

int abc;

int value = 0;

switch ( abc )

{

case 1:

value = 5;

break;

case 2:

value = 10;

break;

default:

value = -1;

break;

}

​

int abc;

int value = 0;

switch ( intValue )

{

case 1:

value = 5;

case 2:

value = 10;

break;

default:

value = -1;

break;

}

​

If abc is 2, the value is set to 10. If the abc is 10, the value is -1. Notice the right column case 1 is missing a break. What is value if abc is 1 for both sides? Is it the same or different?

Classes and Objects

• Class == Recipe for an object
• Subclasses are more specialized recipes that share characteristics with a (base) class. Example:
• Vehicle is a base or parent class
• Car and motorcycle are subclasses
• Object == a class that has been realized, Most of the time there are multiple objects for each class

Classes and Objects - Example

Class: Dog

(sub)Class: GoldenRetriever

(sub)Class: Dalmatian

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Objects of Class GoldenRetriever: B-Dawg, Buddha, Budderball, Mudbud, Rosebud, etc.

Objects of Class Dalmatian: Pongo, Perdita, Lucky, Patch, etc.

Classes and Objects - Example

Class: TalonSRX

Objects: LeftFrontDrive, LeftRearDrive, RightFrontDrive, RightRearDrive

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Class: Automobile

(sub)Class: ChevyCorvette

Objects: JimsCorvette, AnnesCorvette, JaysCorvetter

Activity 7

Which is a class and which is an object

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SuperHero

IronMan

CaptainAmerica

MarvelSuperHero

SpiderMan

WonderWoman

DCSuperHero

Batman

Gamora

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Bob

Minion

Stuart

Kevin

Dave

Jerry

Mark

Phil

Class/Object Variables

• Classname is the variable type
• Initialize to null
• Chassis drive = null;
• Create an object using the new operator
• Chassis drive = new Chassis();

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Activity 8

1. Open TeleopControl.cs
2. Find TODO: #2
3. Create the m_chassis object

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Classes

• Defined in a .cs file (file name matches the classname)
• Using directive provides access to other namespaces
• Define Attributes (characteristics of the objects that get created)
• Define Methods (ways to interact with the objects that are created)
• Attributes & Methods have visibility defined with them
• public - everyone can see/interact
• protected - only the class and its subclasses can see/interact
• private - only the class can see/interact

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Class Attributes

• Variables that are scoped to the entire class (it can be accessed anywhere in the class).
• Each object will have their own attributes (they are not shared). So, in the corvette example above
• JimsCorvette may be black with a manual transmission
• AnnesCorvette may be red with a manual transmission
• JaysCorvette may be yellow with an automatic transmission
• Always use private visibility
• private double speed;
• Should get initialized in the constructor

Class Methods

• Ways to interact with the objects (functions)
• Special Methods:
• Accessors (get attribute values)
• Mutators (set attribute values)
• Generally don’t make public mutators, rather have public methods that do something that will call the appropriate mutators or set the attributes directly
• Constructors (same name as class)
• Gets called when an object is created using the class definition (new classname)
• Destructor (~ plus the class name)
• Gets called when the object gets destroyed

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Class Layout

Provide access to other namespaces

Defines this namespace

Defines class and baseclass (:IDragonGamePad)

using Microsoft.SPOT;

using HeroDemoBots.Common.Controllers.Axis;

using HeroDemoBots.Common.Controllers.Button;

using CTRE.Phoenix;

using CTRE.Phoenix.Controller;

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namespace HeroDemoBots.Common.Controllers

{

public class DragonGamePad : IDragonGamePad

{

Class Layout

Attributes of the class

Constructor

Method - override indicates it replaces a method in a base class

public class DragonGamePad : IDragonGamePad

{

private GameController m_gamepad;

private IButton[] m_buttonAr;

private AnalogAxis[] m_axisAr;

public DragonGamePad()

{

m_gamepad = new GameController(UsbHostDevice.GetInstance());

​

}

public override bool IsButtonPressed

(

BUTTON_IDENTIFIER button /// <I> - button to check

)

{

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Reading a Method Signatures

Visibility ReturnType MethodName( ParameterType ParameterName );

• Visibility: who can call this method (public == everyone, private only this class, protected this class and its subclasses)
• ReturnType: what type of variable does the method call return
• int, double, float, bool, etc.
• ClassName: Name of the class
• MethodName: Name of the method
• ParameterType: type of variable being passed
• int, double, float, bool, etc.
• ParameterName: name of the parameter (optional). Often describes the parameter
• Note: ParemeterType/ParameterName combination can be repeated with comma separators

ClassName objectName = new ClassName();

ParameterType ParameterName = initialValue;

ReturnType returnVariable = objectName.MethodName( ParameterName );

​

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Activity 9

• Open TeleopControl.cs
• Find TODO: #3
• Call the Run method on the m_chassis object
• Open Chassis.cs
• Find TODO: #1 and #2
• Call the methods on m_motor described in the comments
• Try code on test platform

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Activity 10

• Add documentation to:
1. TeleopControl.cs
2. Chassis.cs
3. Program.cs

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Activity 11

• Modify TeleopControl.cs to turn the motor using a different control on the gamepad
• Button A
• Trigger
• Make it switch direction based on which trigger is selected

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