Implemented IEquality<T> and IEqualityComparer<T> interfaces

Author: ahotko

CSharp Code Samples/CodeSamples/CodeSamples.csproj

@@ -59,6 +59,9 @@
     <Compile Include="Classes\ConstructorChainingSample.cs" />
     <Compile Include="Attributes\DebuggingSample.cs" />
     <Compile Include="Classes\ExtensionMethodsSample.cs" />
+    <Compile Include="Comparing\CompareSample.cs" />
+    <Compile Include="Comparing\EqualityComparer.cs" />
+    <Compile Include="Comparing\Equatable.cs" />
     <Compile Include="Constants.cs" />
     <Compile Include="ISampleExecute.cs" />
     <Compile Include="MultiThreading\BackgroundWorkerSample.cs" />

CSharp Code Samples/CodeSamples/Comparing/CompareSample.cs

@@ -0,0 +1,79 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+
+namespace CodeSamples.Comparing
+{
+    public class CompareSample : SampleExecute
+    {
+        private void EquatableAddToList(Collection<EquatableSample> list, EquatableSample item)
+        {
+            if (!list.Contains(item))
+            {
+                list.Add(item);
+                Console.WriteLine($"Added Sample {item.ToString()}");
+            }
+            else
+            {
+                Console.WriteLine($"Sample '{item.ToString()}' already in list; not added");
+            }
+        }
+
+        private void EquatableSample()
+        {
+            var list = new Collection<EquatableSample>();
+
+            var item1 = new EquatableSample() { IntProperty = 1, StringProperty = "One" };
+            var item2 = new EquatableSample() { IntProperty = 1, StringProperty = "Two" };
+            var item3 = new EquatableSample() { IntProperty = 3, StringProperty = "Three" };
+            var item4 = new EquatableSample() { IntProperty = 1, StringProperty = "One" };
+
+            EquatableAddToList(list, item1);
+            EquatableAddToList(list, item2);
+            EquatableAddToList(list, item3);
+            EquatableAddToList(list, item4);
+        }
+
+        private void EqualityComparerAddToList(Dictionary<EqualityComparerSample, string> list, EqualityComparerSample item)
+        {
+            try
+            {
+                list.Add(item, item.StringProperty);
+                Console.WriteLine($"Added Sample {item.ToString()}");
+            }
+            catch (ArgumentException e)
+            {
+                Console.WriteLine($"Sample '{item.ToString()}' already in list; not added");
+            }
+        }
+
+        private void EqualityComparerSample()
+        {
+            //IEqualityComparer<T> is only for dictionaries
+            var list = new Dictionary<EqualityComparerSample, string>(new EqualityComparer());
+
+            var item1 = new EqualityComparerSample() { IntProperty = 1, StringProperty = "One" };
+            var item2 = new EqualityComparerSample() { IntProperty = 1, StringProperty = "Two" };
+            var item3 = new EqualityComparerSample() { IntProperty = 3, StringProperty = "Three" };
+            var item4 = new EqualityComparerSample() { IntProperty = 1, StringProperty = "One" };
+
+            EqualityComparerAddToList(list, item1);
+            EqualityComparerAddToList(list, item2);
+            EqualityComparerAddToList(list, item3);
+            EqualityComparerAddToList(list, item4);
+        }
+
+        public override void Execute()
+        {
+            Title("CompareSampleExecute");
+            LineBreak();
+            Section("IEquatable<T> Sample");
+            EquatableSample();
+            LineBreak();
+            Section("IEqualityComparer<T> Sample");
+            EqualityComparerSample();
+            LineBreak();
+            Finish();
+        }
+    }
+}

CSharp Code Samples/CodeSamples/Comparing/EqualityComparer.cs

@@ -0,0 +1,30 @@
+using System.Collections.Generic;
+
+namespace CodeSamples.Comparing
+{
+    public class EqualityComparer : IEqualityComparer<EqualityComparerSample>
+    {
+        public bool Equals(EqualityComparerSample x, EqualityComparerSample y)
+        {
+            if (x is null && y is null) return true;
+            if (x is null || y is null) return false;
+            return (x.IntProperty == y.IntProperty && x.StringProperty == y.StringProperty);
+        }
+
+        public int GetHashCode(EqualityComparerSample obj)
+        {
+            return obj.IntProperty.GetHashCode() ^ obj.StringProperty.GetHashCode();
+        }
+    }
+
+    public class EqualityComparerSample
+    {
+        public int IntProperty { get; set; }
+        public string StringProperty { get; set; }
+
+        public override string ToString()
+        {
+            return $"Int = {IntProperty}, String = {StringProperty}";
+        }
+    }
+}

CSharp Code Samples/CodeSamples/Comparing/Equatable.cs

@@ -0,0 +1,21 @@
+using System;
+
+namespace CodeSamples.Comparing
+{
+    public sealed class EquatableSample : IEquatable<EquatableSample>
+    {
+        public int IntProperty { get; set; }
+        public string StringProperty { get; set; }
+
+        public bool Equals(EquatableSample other)
+        {
+            if (other is null) return false;
+            return (other.IntProperty == IntProperty && other.StringProperty == StringProperty);
+        }
+
+        public override string ToString()
+        {
+            return $"Int = {IntProperty}, String = {StringProperty}";
+        }
+    }
+}

CSharp Code Samples/CodeSamples/Program.cs

@@ -1,6 +1,7 @@
 using CodeSamples.Alterations;
 using CodeSamples.Attributes;
 using CodeSamples.Classes;
+using CodeSamples.Comparing;
 using CodeSamples.MultiThreading;
 using CodeSamples.Patterns;
 using CodeSamples.SyntacticSugars;
@@ -107,6 +108,11 @@ static void Main(string[] args)
             backgroundWorkerSample.Execute();
             #endregion
 
+            #region Equality
+            var compareSample = new CompareSample();
+            compareSample.Execute();
+            #endregion
+
             Console.WriteLine();
             Console.WriteLine("End Code Samples");