add collections

20210818/20210818.csproj

@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <RootNamespace>_20210818</RootNamespace>
+  </PropertyGroup>
+
+</Project>

20210818/Program.cs

@@ -0,0 +1,156 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+
+namespace _20210818
+{
+    class Program
+    {
+        static void Main(string[] args)
+        {
+            //ArrayListExample(5);
+
+            //HashtablesExample();
+
+            //WorkingWithLists();
+
+            //WorkingWithDictionaries();
+
+            var testString = "the quick brown fox jumps over the lazy dog";
+            ReturnMostUsedCharacterInStringSolution(testString);
+        }
+
+        #region Collections | ArrayList
+
+        public static void ArrayListExample(int numberOfItemsToAdd)
+        {
+            ArrayList list = new ArrayList();
+            for(var i = 0; i < numberOfItemsToAdd; i++)
+            {
+                var strValue = $"Item {i}";
+                decimal someValue = 100.50M;
+                list.Add(someValue);
+                list.Add(strValue);
+                list.Add(null);
+            }
+
+            list.Insert(1, "42");
+            Console.WriteLine(list.Count);
+            foreach(var item in list)
+            {
+                Console.WriteLine(item);
+            }
+
+        }
+
+        #endregion
+
+        #region Collections | Hashtables
+
+        public static void HashtablesExample()
+        {
+            Hashtable table = new Hashtable();
+            table.Add("ONE", 1);
+            table.Add("Hello", "World");
+            table.Add("What is your name?", "Unknown");
+
+            var keys = table.Keys;
+            foreach(var key in keys)
+            {
+                Console.WriteLine($"{key} | {table[key]}");
+            }
+        }
+
+        #endregion
+
+        #region Generics | Lists
+
+        public static void WorkingWithLists()
+        {
+            List<DayOfWeek> DaysOfTheWeek = new List<DayOfWeek>();
+            DaysOfTheWeek.Add(DayOfWeek.Monday);
+            DaysOfTheWeek.Add(DayOfWeek.Tuesday);
+            DaysOfTheWeek.Add(DayOfWeek.Wednesday);
+            DaysOfTheWeek.Add(DayOfWeek.Thursday);
+            DaysOfTheWeek.Add(DayOfWeek.Friday);
+            DaysOfTheWeek.Add(DayOfWeek.Saturday);
+            DaysOfTheWeek.Add(DayOfWeek.Sunday);
+
+            if (!DaysOfTheWeek.Contains(DayOfWeek.Thursday))
+            {
+                Console.WriteLine("It should contain thursday!");
+            }
+
+            for(var i = 0; i < DaysOfTheWeek.Count; i++)
+            {
+                Console.WriteLine(DaysOfTheWeek[i]);
+            }
+        }
+
+        #endregion
+
+        #region Generics | Dictionary
+
+        public static void WorkingWithDictionaries()
+        {
+            Dictionary<string, int> myDictionary = new Dictionary<string, int>();
+            myDictionary.Add("Hello", 0);
+            myDictionary["World"] = 1;
+
+            foreach (KeyValuePair<string, int> pair in myDictionary)
+            {
+                Console.WriteLine($"Key: {pair.Key} | Value: {pair.Value}");
+            }
+
+        }
+
+        #endregion
+
+
+        #region Random Interview Question
+
+        public static void ReturnMostUsedCharacterInStringSolution(string Input)
+        {
+            var maxKey = new char();
+            var maxCount = 0;
+
+            Dictionary<char, int> characterCount = new Dictionary<char, int>();
+            foreach(var character in Input)
+            {
+                if (characterCount.ContainsKey(character))
+                {
+                    characterCount[character]++;
+                }
+                else
+                {
+                    characterCount[character] = 1;
+                }
+
+                var value = characterCount[character];
+                if (value > maxCount)
+                {
+                    maxCount = value;
+                    maxKey = character;
+                }
+            }
+
+            // var maxKey = new char();
+            // var maxCount = 0;
+            // foreach(KeyValuePair<char, int> pair in characterCount)
+            // {
+            //     if (pair.Value > maxCount)
+            //     {
+            //         maxCount = pair.Value;
+            //         maxKey = pair.Key;
+            //     }
+            // }
+
+            Console.WriteLine($"Character '{maxKey}' showed up {maxCount} times.");
+        }
+
+
+        #endregion
+
+
+    }
+}