int numberOfApples = 12;
decimal pricePerApple = 0.35M;

WriteLine(
  format: "{0} apples cost {1:C}",
  arg0: numberOfApples,
  arg1: pricePerApple * numberOfApples);

string formatted = string.Format(
  format: "{0} apples cost {1:C}",
  arg0: numberOfApples,
  arg1: pricePerApple * numberOfApples);

//WriteToFile(formatted); // writes the string into a file

WriteLine($"{numberOfApples} apples cost {pricePerApple * numberOfApples:C}");

Write("Type your first name and press ENTER: ");
string? firstName = ReadLine(); // nulls are expected

Write("Type your age and press ENTER: ");
string age = ReadLine()!; // null won't be returned

WriteLine(
  $"Hello {firstName}, you look good for {age}.");

Write("Press any key combination: ");
ConsoleKeyInfo key = ReadKey();
WriteLine();
WriteLine("Key: {0}, Char: {1}, Modifiers: {2}",
  arg0: key.Key,
  arg1: key.KeyChar,
  arg2: key.Modifiers);