Initial commit

vscode/Chapter04/WritingFunctions/Program.Functions.cs

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+partial class Program
+{
+  static void TimesTable(byte number, byte size = 12)
+  {
+    WriteLine($"This is the {number} times table with {size} rows:");
+    for (int row = 1; row <= size; row++)
+    {
+      WriteLine($"{row} x {number} = {row * number}");
+    }
+    WriteLine();
+  }
+
+  static decimal CalculateTax(
+    decimal amount, string twoLetterRegionCode)
+  {
+    decimal rate = 0.0M;
+
+    switch (twoLetterRegionCode)
+    {
+      case "CH": // Switzerland
+        rate = 0.08M;
+        break;
+      case "DK": // Denmark
+      case "NO": // Norway
+        rate = 0.25M;
+        break;
+      case "GB": // United Kingdom
+      case "FR": // France
+        rate = 0.2M;
+        break;
+      case "HU": // Hungary
+        rate = 0.27M;
+        break;
+      case "OR": // Oregon
+      case "AK": // Alaska
+      case "MT": // Montana
+        rate = 0.0M;
+        break;
+      case "ND": // North Dakota
+      case "WI": // Wisconsin
+      case "ME": // Maine
+      case "VA": // Virginia
+        rate = 0.05M;
+        break;
+      case "CA": // California
+        rate = 0.0825M;
+        break;
+      default: // most US states
+        rate = 0.06M;
+        break;
+    }
+    return amount * rate;
+  }
+
+  /// <summary>
+  /// Pass a 32-bit integer and it will be converted into its ordinal equivalent.
+  /// </summary>
+  /// <param name="number">Number is a cardinal value e.g. 1, 2, 3, and so on.</param>
+  /// <returns>Number as an ordinal value e.g. 1st, 2nd, 3rd, and so on.</returns>
+
+  static string CardinalToOrdinal(int number)
+  {
+    switch (number)
+    {
+      case 11: // special cases for 11th to 13th
+      case 12:
+      case 13:
+        return $"{number}th";
+      default:
+        int lastDigit = number % 10;
+        string suffix = lastDigit switch
+        {
+          1 => "st",
+          2 => "nd",
+          3 => "rd",
+          _ => "th"
+        };
+        return $"{number}{suffix}";
+    }
+  }
+
+  static void RunCardinalToOrdinal()
+  {
+    for (int number = 1; number <= 40; number++)
+    {
+      Write($"{CardinalToOrdinal(number)} ");
+    }
+    WriteLine();
+  }
+
+  static int Factorial(int number)
+  {
+    if (number < 0)
+    {
+      throw new ArgumentException(message:
+        "The factorial function is defined for non-negative integers only.",
+        paramName: "number");
+    }
+    else if (number == 0)
+    {
+      return 1;
+    }
+    else
+    {
+      checked // for overflow
+      {
+        return number * Factorial(number - 1);
+      }
+    }
+  }
+
+  static void RunFactorial()
+  {
+    for (int i = 1; i <= 14; i++)
+    {
+      try
+      {
+        WriteLine($"{i}! = {Factorial(i):N0}");
+      }
+      catch (System.OverflowException)
+      {
+        WriteLine($"{i}! is too big for a 32-bit integer.");
+      }
+    }
+  }
+
+  static int FibImperative(int term)
+  {
+    if (term == 1)
+    {
+      return 0;
+    }
+    else if (term == 2)
+    {
+      return 1;
+    }
+    else
+    {
+      return FibImperative(term - 1) + FibImperative(term - 2);
+    }
+  }
+  static void RunFibImperative()
+  {
+    for (int i = 1; i <= 30; i++)
+    {
+      WriteLine("The {0} term of the Fibonacci sequence is {1:N0}.",
+        arg0: CardinalToOrdinal(i),
+        arg1: FibImperative(term: i));
+    }
+  }
+
+  static int FibFunctional(int term) =>
+  term switch
+  {
+    1 => 0,
+    2 => 1,
+    _ => FibFunctional(term - 1) + FibFunctional(term - 2)
+  };
+
+  static void RunFibFunctional()
+  {
+    for (int i = 1; i <= 30; i++)
+    {
+      WriteLine("The {0} term of the Fibonacci sequence is {1:N0}.",
+        arg0: CardinalToOrdinal(i),
+        arg1: FibFunctional(term: i));
+    }
+  }
+
+}

vscode/Chapter04/WritingFunctions/Program.cs

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+/*
+TimesTable(7);
+
+TimesTable(7, 20);
+
+TimesTable(number: 7, size: 10);
+*/
+
+/*
+decimal taxToPay = CalculateTax(amount: 149, twoLetterRegionCode: "FR");
+WriteLine($"You must pay {taxToPay} in tax.");
+*/
+
+//RunCardinalToOrdinal();
+
+//RunFactorial();
+
+//RunFibImperative();
+
+RunFibFunctional();

vscode/Chapter04/WritingFunctions/WritingFunctions.csproj

@@ -0,0 +1,14 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+	<PropertyGroup>
+		<OutputType>Exe</OutputType>
+		<TargetFramework>net7.0</TargetFramework>
+		<ImplicitUsings>enable</ImplicitUsings>
+		<Nullable>enable</Nullable>
+	</PropertyGroup>
+
+	<ItemGroup>
+		<Using Include="System.Console" Static="true" />
+	</ItemGroup>
+
+</Project>