cs11dotnet7/vscode/Chapter03/SelectionStatements/Program.cs

string password = "ninja";
if (password.Length < 8)
{
  WriteLine("Your password is too short. Use at least 8 characters.");
}
else
{
  WriteLine("Your password is strong.");
}

// add and remove the "" to change the behavior
object o = 3;
int j = 4;

if (o is int i)
{
  WriteLine($"{i} x {j} = {i * j}");
}
else
{
  WriteLine("o is not an int so it cannot multiply!");
}

int number = Random.Shared.Next(1, 7);
WriteLine($"My random number is {number}");

switch (number)
{
  case 1:
    WriteLine("One");
    break; // jumps to end of switch statement
  case 2:
    WriteLine("Two");
    goto case 1;
  case 3: // multiple case section
  case 4:
    WriteLine("Three or four");
    goto case 1;
  case 5:
    goto A_label;
  default:
    WriteLine("Default");
    break;
} // end of switch statement
WriteLine("After end of switch");
A_label:
WriteLine($"After A_label");

// Pattern matching with the switch statement

Animal?[] animals = new Animal?[]
{
  new Cat { Name = "Karen", Born = new(year: 2022, month: 8, day: 23), 
    Legs = 4, IsDomestic = true },
  null,
  new Cat { Name = "Mufasa", Born = new(year: 1994, month: 6, day: 12) },
  new Spider { Name = "Sid Vicious", Born = DateTime.Today, 
    IsPoisonous = true},
  new Spider { Name = "Captain Furry", Born = DateTime.Today }
};

foreach (Animal? animal in animals)
{
  string message;

  switch (animal)
  {
    case Cat fourLeggedCat when fourLeggedCat.Legs == 4:
      message = $"The cat named {fourLeggedCat.Name} has four legs.";
      break;
    case Cat wildCat when wildCat.IsDomestic == false:
      message = $"The non-domestic cat is named {wildCat.Name}.";
      break;
    case Cat cat:
      message = $"The cat is named {cat.Name}.";
      break;
    default: // default is always evaluated last
      message = $"The animal named {animal.Name} is a {animal.GetType().Name}.";
      break;
    case Spider spider when spider.IsPoisonous:
      message = $"The {spider.Name} spider is poisonous. Run!";
      break;
    case null:
      message = "The animal is null.";
      break;
  }
  WriteLine($"switch statement: {message}");
  
  message = animal switch
  {
    Cat fourLeggedCat when fourLeggedCat.Legs == 4
      => $"The cat named {fourLeggedCat.Name} has four legs.",
    Cat wildCat when wildCat.IsDomestic == false
      => $"The non-domestic cat is named {wildCat.Name}.",
    Cat cat
      => $"The cat is named {cat.Name}.",
    Spider spider when spider.IsPoisonous
      => $"The {spider.Name} spider is poisonous. Run!",
    null
      => "The animal is null.",
    _
      => $"The animal named {animal.Name} is a {animal.GetType().Name}."
  };
  WriteLine($"switch expression: {message}");
}