added gls project

Checksums/GLS/GLS.csproj

@@ -0,0 +1,8 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net5.0</TargetFramework>
+  </PropertyGroup>
+
+</Project>

Checksums/GLS/Program.cs

@@ -0,0 +1,146 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace GLS
+{
+    internal class Program
+    {
+        static void Main(string[] args)
+        {
+            Console.WriteLine("Hello World!");
+            Console.WriteLine("This Utility calculates GLS Parcel numbers.");
+            while (true)
+            {
+                Console.WriteLine("Please press:\n- (n) to enter a new Number to generate\n- (c) to clear the console\n- (q) to quit the application");
+
+                // read key from console
+                ConsoleKeyInfo cki = Console.ReadKey();
+
+                string action = "NULL";
+                switch (cki.Key)
+                {
+                    case ConsoleKey.N:
+                        {
+                            // N was pressed, set action to new
+                            action = "NEW";
+                            break;
+                        }
+                    case ConsoleKey.Q:
+                        {
+                            // return from Main Method, effectively exiting from application
+                            return;
+                        }
+                    case ConsoleKey.C:
+                        {
+                            // return from Main Method, effectively exiting from application
+                            action = "CLEAR";
+                            break;
+                        }
+                    default:
+                        {
+                            // something wrong was pressed
+                            action = "NULL";
+                            break;
+                        }
+                }
+
+                if (action == "NULL")
+                {
+                    // continue in loop, effectively giving user prompt again
+                    Console.WriteLine("The key pressed is not accepted, try again.");
+                    continue;
+                }
+
+                if (action == "CLEAR")
+                {
+                    // optionally clear console
+                    Console.Clear();
+                }
+
+                // create List to hold numbers that were put in
+                List<int> parsedNumbers = new();
+
+                while (true)
+                {
+                    Console.WriteLine("\rPlease type the GLS parcel number without the checksum (or press q and enter to quit):");
+
+                    // get input from user
+                    string input = Console.ReadLine();
+
+                    if (input == "q")
+                    {
+                        // user pressed q, exit
+                        return;
+                    }
+
+                    if (input == null || input == "")
+                    {
+                        // nothing was put in, rerun loop and let user retry
+                        continue;
+                    }
+
+                    // clear number list to make sure the numbers don't overlap from previous attempt
+                    parsedNumbers.Clear();
+
+                    // split all characters into individual strings
+                    string[] splitCharacters = input.Select(x => x.ToString()).ToArray();
+
+                    // do more validation
+                    foreach (string character in splitCharacters)
+                    {
+                        int parsedNum;
+
+                        if (int.TryParse(character, out parsedNum))
+                        {
+                            // number is valid, add to parsednumbers list
+                            parsedNumbers.Add(parsedNum);
+                        }
+                    }
+
+                    // ensure we got 11 digits, because that is the length of the GLS number without checksum
+                    if (parsedNumbers.Count != 11 || parsedNumbers.Count != splitCharacters.Length)
+                    {
+                        // number of digits is not correct, let the user retry
+                        continue;
+                    }
+
+                    // add variable to hold sum of result of multiplication
+                    // initial value is 1 because then we can skip adding 1 later on
+                    int tempSum = 1;
+
+                    // we now know we have exactly 11 digits
+                    for (int i = 0; i < parsedNumbers.Count; i++)
+                    {
+                        int thisNumber = parsedNumbers[i];
+
+                        if (i % 2 == 0)
+                        {
+                            // if index is even, multiply with 3
+                            thisNumber *= 3;
+                        }
+
+                        // add maybe multiplied number to temporary sum variable
+                        tempSum += thisNumber;
+                    }
+
+                    // modulo 10 the sum
+                    int tempSumMod10 = tempSum % 10;
+
+                    // subtract mod 10 from 10, mod 10 again to remove 10 if the initial mod 10 result is 0
+                    int checksum = (10 - tempSumMod10) % 10;
+
+                    // write results to console
+                    Console.WriteLine("The calculated checksum is:         -----------" + checksum);
+                    Console.WriteLine("The entire parcel number should be: " + input + checksum);
+
+                    // print newlines to console for some space
+                    Console.WriteLine("\n\n");
+
+                    // calculation is done, break out of loop, go back to initial new/clear/quit prompt
+                    break;
+                }
+            }
+        }
+    }
+}