Added C# implementation of Harshad Numbers

Davipb · Davipb · commit 667a03ce9762 · 2015-01-04T22:40:05.000-02:00
diff --git a/10_Harshad_Number/C#/Davipb/HarshadNumbers.cs b/10_Harshad_Number/C#/Davipb/HarshadNumbers.cs
@@ -0,0 +1,43 @@
+﻿using System;
+using System.Collections.Generic;
+
+namespace HarshadNumbers
+{
+	public static class HarshadNumbers
+	{
+
+		/// <summary>
+		/// Checks weather or not a number is a 10-Harshad Number
+		/// </summary>
+		/// <param name="l">The number to be tested</param>
+		/// <returns>True if l is a Harshad Number</returns>
+		public static bool IsHarshad(ulong l)
+		{
+			// We don't want division by zero, so let's make sure the universe doesn't explode
+			if (l == 0)
+				return false;
+
+			ulong sum = 0;
+
+			// Loop through each digit, adding them to the total sum
+			foreach (char c in l.ToString())
+				sum += ulong.Parse(c.ToString());
+
+			// If the remainder of the division is zero, the number is divisble.
+			return (l % sum == 0);
+		}
+
+		// Something extra, the method below is not essential
+
+		/// <summary>
+		/// Generator method that generates all (computable) Harshad Numbers
+		/// </summary>
+		/// <returns>Harshad numbers, in crescent order, starting at 1</returns>
+		public static IEnumerable<ulong> AllHarshadNumbers()
+		{
+			for (ulong l = 0; ; l++)
+				if (IsHarshad(l))
+					yield return l;
+		}
+	}
+}
diff --git a/10_Harshad_Number/C#/Davipb/HarshadNumbers_test.cs b/10_Harshad_Number/C#/Davipb/HarshadNumbers_test.cs
@@ -0,0 +1,35 @@
+﻿using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace HarshadNumbers
+{
+	public static class HarshadNumbers_test
+	{
+		public static void Main(string[] args)
+		{
+			Test();
+			Console.ReadKey();
+		}
+
+		public static void Test()
+		{
+			Console.Title = "HarshadNumbers unit test";
+
+			Console.WriteLine("Is N a 10-Harshad number?");
+			Console.Write("N = ");
+			Console.WriteLine(HarshadNumbers.IsHarshad(ulong.Parse(Console.ReadLine())).ToString());
+
+			Console.WriteLine();
+
+			Console.WriteLine("Get the first N 10-Harshad Numbers");
+			Console.Write("N = ");
+
+			int max = int.Parse(Console.ReadLine());
+			for (int i = 0; i < max; i++)
+				Console.WriteLine("{0}: {1}", i, HarshadNumbers.AllHarshadNumbers().ElementAt(i));
+		}
+	}
+}
