// See https://aka.ms/new-console-template for more information
Console.WriteLine("Hello, World!");

$  dotnet run Program.cs

string firstName = "Someone";
char userOption = 'A';
int gameScore = 123;
float percentage = 12.10;
double portion = 4.556
decimal particlesPerMillion = 123.4567;
bool processedCustomer = true;

var message = "Hello world!";

const int ConstNum = 5;

int sum = 7 + 5;
int difference = 7 - 5;
int product = 7 * 5;
int quotient = 7 / 5;
int modulus = 7 % 5;

Console.WriteLine("Sum: " + sum); // Sum: 12
Console.WriteLine("Difference: " + difference); // Difference: 2
Console.WriteLine("Product: " + product); // Product: 35
Console.WriteLine("Quotient: " + quotient); // Quotient: 1
Console.WriteLine($"Modulus: {7 % 5}"); // Modulus: 2

int value = 1;

value = value + 1;
Console.WriteLine("First increment: " + value); // First increment: 2

value += 1;
Console.WriteLine("Second increment: " + value); // Second increment: 3

value++;
Console.WriteLine("Third increment: " + value); // Third increment: 4

value = value - 1;
Console.WriteLine("First decrement: " + value); // First decrement: 3

value -= 1;
Console.WriteLine("Second decrement: " + value); // Second decrement: 2

value--;
Console.WriteLine("Third decrement: " + value); // Third decrement: 1

// Character escape sequences
Console.WriteLine("Hello\nWorld!");
Console.WriteLine("Hello\tWorld!");
Console.WriteLine("Hello \"World\"!"); // Hello "World"!
Console.WriteLine("c:\\source\\repos"); // c:\source\repos

// Verbatim string literal
Console.WriteLine(@"    c:\source\repos    
        (this is where your code goes)");

//    c:\source\repos    
//        (this is where your code goes)

// Unicode escape character
Console.WriteLine("\u3053\u3093\u306B\u3061\u306F World!"); // こんにちは World!

string firstName = "Bob";
string greeting = "Hello";
string message = greeting + " " + firstName + "!";
Console.WriteLine(message); // Hello Bob!

string firstName = "Bob";
string greeting = "Hello";
Console.WriteLine($"{greeting} {firstName}!"); // Hello Bob!

// Combine verbatim literals and string interpolation
string projectName = "First-Project";
Console.WriteLine($@"C:\Output\{projectName}\Data"); // C:\Output\First-Project\Data

string[] customerIds = new string[3];
string[] customerIds = [ "A123", "B456", "C789" ]; // Introduced in C#12
string[] customerIds = { "A123", "B456", "C789" }; // Older version

string[] customerIds = new string[3];

customerIds[0] = "C123";
customerIds[1] = "C456";
customerIds[2] = "C789";

string[] customerIds = [ "A123", "B456", "C789" ];
Console.WriteLine($"There are {customerIds.Length} customers.");

var pt = (X: 1, Y: 2);

var slope = (double)pt.Y / (double)pt.X;
Console.WriteLine($"A line from the origin to the point {pt} has a slope of {slope}."); // A line from the origin to the point (1, 2) has a slope of 2.

Console.WriteLine("Generating random numbers:");
DisplayRandomNumbers(); // 17 29 46 36 3 

void DisplayRandomNumbers() 
{
    Random random = new Random();

    for (int i = 0; i < 5; i++) 
    {
        Console.Write($"{random.Next(1, 100)} ");
    }

    Console.WriteLine();
}

CountTo(5);

void CountTo(int max) 
{
  for (int i = 0; i < max; i++)
  {
    Console.Write($"{i}, "); // 0, 1, 2, 3, 4
  }
}

CountTo();

void CountTo(int max = 10) 
{
  for (int i = 0; i < max; i++)
  {
    Console.Write($"{i}, "); // 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
  }
}

int sum = SumTo(5);
Console.Write($"sum: {sum}"); // sum: 15

int CountTo(int max) 
{
  int result = 0;

  for (int i = 1; i <= max; i++)
  {
    result += i;
  }

  return result;
}

Console.WriteLine("Hello World!");

Random dice = new Random();
int roll = dice.Next(1, 7);

string color = "black";

if (color == "black")
{
  Console.WriteLine("It's black.");
}
else if (color == "white")
{
  Console.WriteLine("It's white.");
}
else {
  Console.WriteLine("It's other color.");
}

int saleAmount = 1001;
int discount = saleAmount > 1000 ? 100 : 50;
Console.WriteLine($"Discount: {discount}");

bool flag = true;
if (flag)
{
  int value = 10;
  Console.WriteLine($"Inside the code block: {value}"); // Prints value.
}
Console.WriteLine($"Outside the code block: {value}"); // Gives error because value is declared inside the if code block.

string fruit = "apple";

switch (fruit)
{
  case "apple":
    Console.WriteLine($"App will display information for apple.");
    break;
  case "banana":
    Console.WriteLine($"App will display information for banana.");
    break;
  case "cherry":
    Console.WriteLine($"App will display information for cherry.");
    break;
  default:
    Console.WriteLine($"App will not display information about any fruit.");
    break;
}

string[] names = { "Rowena", "Robin", "Bao" };

foreach (string name in names)
{
  Console.WriteLine(name); // "Rowena", "Robin", "Bao"
}

for (int i = 0; i < 10; i++)
{
  if (i > 5) {
    break;
  }
  Console.WriteLine(i); // 1, 2, 3, 4, 5
}

Random random = new Random();
int current = 0;

do
{
  current = random.Next(1, 11);
  
  if (current >= 8) {
    continue;
  }
  
  Console.WriteLine(current);
} while (current != 7);

Random random = new Random();
int current = random.Next(1, 11);

while (current >= 3)
{
  Console.WriteLine(current);
  current = random.Next(1, 11);
}
Console.WriteLine($"Last number: {current}");

decimal myDecimal = 3.14m;
Console.WriteLine($"decimal: {myDecimal}"); // decimal: 3.14

int myInt = (int)myDecimal;
Console.WriteLine($"int: {myInt}"); // int: 3

int first = 5;
int second = 7;
string message = first.ToString() + second.ToString();
Console.WriteLine(message); // 57

string first = "5";
string second = "7";
int sum = int.Parse(first) + int.Parse(second);
Console.WriteLine(sum); // 12

string value = "102";
int result = 0;
if (int.TryParse(value, out result))
{
   Console.WriteLine($"Measurement: {result}");
}
else
{
   Console.WriteLine("Unable to report the measurement.");
}

string value1 = "5";
string value2 = "7";
int result = Convert.ToInt32(value1) * Convert.ToInt32(value2);
Console.WriteLine(result); // 35

string[] pallets = [ "B14", "A11", "B12", "A13" ];

Console.WriteLine("Sorted...");
Array.Sort(pallets);
foreach (var pallet in pallets)
{
   Console.WriteLine($"-- {pallet}"); // A11, A13, B12, B14
}

string[] pallets = [ "A11", "A13", "B12", "B14" ];

Console.WriteLine("Reversed...");
Array.Reverse(pallets);
foreach (var pallet in pallets)
{
   Console.WriteLine($"-- {pallet}"); // B14, B12, A13, A11
}

string[] pallets = [ "B14", "A11", "B12", "A13" ];
Console.WriteLine("");

Array.Clear(pallets, 0, 2);
Console.WriteLine($"Clearing 2 ... count: {pallets.Length}");
foreach (var pallet in pallets)
{
   Console.WriteLine($"-- {pallet}"); // null, null, B12, A13
}

string[] pallets =  ["B14", "A11", "B12", "A13" ];
Console.WriteLine("");

Array.Resize(ref pallets, 6);
Console.WriteLine($"Resizing 6 ... count: {pallets.Length}");

pallets[4] = "C01";
pallets[5] = "C02";

foreach (var pallet in pallets)
{
   Console.WriteLine($"-- {pallet}"); // B14, A11, B12, A13, C01, C02
}

char[] valueArray = ['a', 'b', 'c']
Array.Reverse(valueArray);
// string result = new string(valueArray);
string result = String.Join("|", valueArray); // a|b|c
Console.WriteLine(result);

string result = "123|456|789";
string[] items = result.Split('|');
foreach (string item in items)
{
   Console.WriteLine(item); // 123, 456, 789
}

string first = "Hello";
string second = "World";
string result = string.Format("{0} {1}!", first, second);
Console.WriteLine(result); // Hello World!

decimal price = 123.45m;
int discount = 50;
Console.WriteLine($"Price: {price:C} (Save {discount:C})"); // Price: $123.45 (Save $50.00)

decimal measurement = 123456.78912m;
Console.WriteLine($"Measurement: {measurement:N} units"); // Measurement: 123,456.79 units
Console.WriteLine($"Measurement: {measurement:N4} units"); // Measurement: 123,456.7891 units

decimal tax = .36785m;
Console.WriteLine($"Tax rate: {tax:P2}"); // Tax rate: 36.79%

string input = "Pad this";
Console.WriteLine(input.PadLeft(12)); // " 	Pad this"
Console.WriteLine(input.PadLeft(12, '*')); // "****Pad this"
Console.WriteLine(input.PadRight(12, '*')); // "Pad this****"

string message = "Find what is (inside the parentheses)";

int openingPosition = message.IndexOf('(');
int closingPosition = message.IndexOf(')');

Console.WriteLine(openingPosition); // 13
Console.WriteLine(closingPosition); // 36

string message = "What is the value <span>between the tags</span>?";

const string openSpan = "<span>";
const string closeSpan = "</span>";

int openingPosition = message.IndexOf(openSpan);
int closingPosition = message.IndexOf(closeSpan);

openingPosition += openSpan.Length;
int length = closingPosition - openingPosition;
Console.WriteLine(message.Substring(openingPosition, length)); // between the tags

string message = "hello there!";

int first_h = message.IndexOf('h');
int last_h = message.LastIndexOf('h');
Console.WriteLine($"For the message: '{message}', the first 'h' is at position {first_h} and the last 'h' is at position {last_h}."); 
// For the message: 'hello there!', the first 'h' is at position 0 and the last 'h' is at position 7.

string message = "Hello, world!";
char[] charsToFind = { 'a', 'e', 'i' };

int index = message.IndexOfAny(charsToFind);

Console.WriteLine($"Found '{message[index]}' in '{message}' at index: {index}."); // Found 'e' in 'Hello, world!' at index: 1.

string data = "12345John Smith          5000  3  ";
string updatedData = data.Remove(5, 20);
Console.WriteLine(updatedData); // 123455000  3  

string message = "This--is--ex-amp-le--da-ta";
message = message.Replace("--", " ");
message = message.Replace("-", "");
Console.WriteLine(message); // This is example data

string greeting = "      Hello World!       ";
Console.WriteLine($"[{greeting}]"); // "      Hello World!       "

string trimmedGreeting = greeting.TrimStart();
Console.WriteLine($"[{trimmedGreeting}]"); // "Hello World!       "

trimmedGreeting = greeting.TrimEnd();
Console.WriteLine($"[{trimmedGreeting}]"); // "      Hello World!"

trimmedGreeting = greeting.Trim();
Console.WriteLine($"[{trimmedGreeting}]"); // "Hello World!"

string songLyrics = "You say goodbye, and I say hello";
Console.WriteLine(songLyrics.Contains("goodbye")); // True
Console.WriteLine(songLyrics.Contains("greetings")); // False

// A type that is defined as a class is a reference type.

//[access modifier] - [class] - [identifier]
public class Customer
{
  // Fields, properties, methods and events go here...
}

Customer object1 = new Customer(); // object1 is a reference to an allocated space that will know where the object exists.
Customer object2; // Reference to null

Customer object3 = new Customer(); 
Customer object4 = object3; // object4 has the same reference as object3. If any of both instances changes, the other one does as well. Not recommended to do that.

public class Container
{
  private int _capacity;

  public Container(int capacity) => _capacity = capacity;
}

public class Container(int capacity)
{
  private int _capacity = capacity;
}

public class Person
{
  public required string LastName { get; set; }
  public required string FirstName { get; set; }
}

var p1 = new Person(); // Error! Required properties not set
var p2 = new Person() { FirstName = "Grace", LastName = "Hopper" };

abstract class Shape
{
  public abstract int GetArea();
}

class Square : Shape
{
  private int _side;

  public Square(int n) => _side = n;

  // GetArea method is required to avoid a compile-time error.
  public override int GetArea() => _side * _side;

  static void Main()
  {
    var sq = new Square(12);
    Console.WriteLine($"Area of the square = {sq.GetArea()}");
  }
}
// Output: Area of the square = 144

// Abstract class
abstract class BaseClass
{
  protected int _x = 100;
  protected int _y = 150;

  // Abstract method
  public abstract void AbstractMethod();

  // Abstract properties
  public abstract int X { get; }
  public abstract int Y { get; }
}

class DerivedClass : BaseClass
{
  public override void AbstractMethod()
  {
    _x++;
    _y++;
  }

  public override int X   // overriding property
  {
    get
    {
      return _x + 10;
    }
  }

  public override int Y   // overriding property
  {
    get
    {
      return _y + 10;
    }
  }

  static void Main()
  {
    var o = new DerivedClass();
    o.AbstractMethod();
    Console.WriteLine($"x = {o.X}, y = {o.Y}");
  }
}
// Output: x = 111, y = 161

public abstract class Shape
{
  public string Color { get; set; }

  // Constructor of the abstract class
  protected Shape(string color)
  {
    Color = color;
    Console.WriteLine($"Created a shape with color {color}.");
  }

  // Abstract method that must be implemented by derived classes
  public abstract double CalculateArea();
}

public class Square : Shape
{
  public double Side { get; set; }

  // Constructor of the derived class calling the base class constructor
  public Square(string color, double side) : base(color)
  {
    Side = side;
  }

  public override double CalculateArea()
  {
    return Side * Side;
  }
}

public class Program
{
  public static void Main(string[] args)
  {
    Square square = new Square("red", 5);
    Console.WriteLine($"Area of the square: {square.CalculateArea()}");            
  }
}