C# Crash Course

// Create a new list.
List<string> listOfStrings = new List<string>();

listOfStrings.Add("Hello World!");

// Insert into the list at index #1 
listOfStrings.Insert(1, "Hello Eric!"); 

listOfStrings[0] = "Goodbye cruel world...";

// Remove the string at index #1
listOfStrings.RemoveAt(1); 

// Delete all values
listOfStrings.Clear(); 

int itemsInList = listOfStrings.Count; // 0

var phoneBook = new Dictionary<string, int>();

phoneBook["Gates, Bill"] = 5550100;
phoneBook["Bezos, Jeff"] = 5551234;

int billsNumber = phoneBook["Gates, Bill"];

// Same dictionary but with values initialized
// instead of set later.
var phoneBook = new Dictionary<string, int>
{ 
    {"BillyG", 5550100},
    {"Bezo$", 5551234}
};

// A dictionary within a dictionary
public Dictionary<string, Dictionary<int, string>> sftp =
new Dictionary<string, Dictionary<int, string>>
{
    {
        "sftp.example.com",
        new Dictionary<int, string>
        {
            { 22, "SFTP/SSH" },
        }
    }
};

int menuChoice = 3;

switch (menuChoice)
{
  case 1:
    Console.WriteLine("Option one");
    break;
  case 2:
    Console.WriteLine("Option two");
    break;
  case 3:
    Console.WriteLine("Option three");
    break;
  default:
    Console.WriteLine("That's not an option!");
    break;
}

if (score >= 100)
    Console.WriteLine("Perfect! You won!");
else if (score < 100 && score >= 65)
{
    // Multiple line statement bodies require curly braces
    Console.WriteLine("Not bad.");
    Console.WriteLine("But you can do better. Try again.");
}
else
    Console.WriteLine("Sorry, you lose.");

if (levelComplete)
    Console.WriteLine("You've beaten the level!");

// Ternary operator
Console.WriteLine((score > 70) ? "You passed!" : "Fail"); 

// Returns nothing.
public static void CountToTen()
{
    for (int i = 0; i < 10; i++)
        Console.WriteLine(i);
}

// The returns a float.
public float Average()
{
    // Need a float or decimal type for non-integer values
    float total; 

    for (int i = 0; i < 10; i++)
        // Equivalent to total = total + i;
        total += i;

    return total / 10;
}


// Method takes two int parameters and returns nothing.
static void Count(int startingNumber, int numberToCountTo)
{
    for (int i = startingNumber; i <= numberToCountTo; i++)
        Console.WriteLine(i);
}

// Calling a standard (instance) method
SomeClass instance = new SomeClass();
instance.InstanceMethod(); // Compiles
instance.StaticMethod(); // Won't compile

instance.InstanceMethodWithArgument(25);

// Calling a static method
SomeClass.StaticMethod(); // Compiles
SomeClass.InstanceMethod(); // Won't compile

SomeClass.StaticMethodWithArgument(25);

// Empty class. Valid but kinda boring.
class Player
{
}

// A class with a few instance variables.
class Player
{
    private string _name;
    private int _score;
    private int _livesLeft;
}

// A class with instance variables and a constructor.
class Player
{
    private string _name;
    private int _score;
    private int _livesLeft;

    public Player(string name)
    {
      this._name = name;
    }
}

// Methods in a class
class Player
{
    private string _name;
    private int _score;
    private int _livesLeft;

    public Player(string name)
    {
        this._name = name;
    }

    public void AddPoints(int points)
    {
        _score += points;
    }
}

// Define a class property called Score
class Player
{
    // Note the visibility is public.
    public int Score { get; set; }
}

// Instance a new Player object with a default score
Player player = new Player("Eric") { score = 100 };

// Change the player score property directly
// without defining a SetScore or GetScore method
player.Score = 95;

// Explicitly defined property exposing a private variable.
class PlayerAlt1
{
    private int _score;

    public int Score
    {
        get => _score;  // public by default
        set => _score = value; // value is just a C# keyword
    }
}

Player playerAlt1 = new PlayerAlt1("Eric") { score = 100 };

// Basically the same behavior. Just more code.
playerAlt1.Score = 95;


// Properties can also refer to methods that modify how the
// the class can get or set the value.
class PlayerAlt2
{
    private int _score;

    public int Score
    {
        get => _score;
        private set => SetScore(value)
    }

    private void SetScore(int value)
    {
        _score = value;

        if (_score >= 100)
            Console.Writeline("Good job!");
    }
}

// The player is a Player type
Player player = new Player("Eric");

// Accessing methods in a class
player.AddPoints(10);
int currentScore = player.GetScore();
Console.WriteLine(currentScore); // Returns 10
Console.WriteLine(player.GetName()); // Returns "Eric"

// See "properties" for a better way to get and set values