--- title: "How to combine two arrays without duplicate values in C#?" description: "How to combine two arrays without duplicate values in C#?" author: "Steilla Mitchel" published: 2024-06-11 updated: 2024-06-11 canonical: https://www.mindstick.com/forum/160711/how-to-combine-two-arrays-without-duplicate-values-in-c-sharp category: "c#" tags: ["c#", ".net"] reading_time: 4 minutes --- # How to combine two arrays without duplicate values in C#? How to [combine](https://www.mindstick.com/interview/1043/how-can-i-combined-two-variable-together) [two arrays](https://www.mindstick.com/forum/161074/how-to-compare-two-arrays-to-each-other-in-javascript) without [duplicate values](https://www.mindstick.com/forum/157764/how-to-find-duplicate-values-in-a-sql-table) in C#? ## Replies ### Reply by Ravi Vishwakarma One way to combine two [arrays](https://www.mindstick.com/articles/11955/arrays-and-its-limitations) without [duplicate](https://www.mindstick.com/forum/160911/sql-query-to-find-duplicate-records-in-a-table-in-sql-server) [values](https://www.mindstick.com/forum/327/sum-textbox-values) in C# is to use LINQ and the `Union` method. Here's how you can do it: ```cs using System; using System.Linq; class Program { static void Main() { int[] array1 = { 1, 2, 3, 4 }; int[] array2 = { 3, 4, 5, 6 }; int[] combinedArray = array1.Union(array2).ToArray(); foreach (var item in combinedArray) { Console.WriteLine(item); } } } ``` In this example, `Union` is used to merge `array1` and `array2`. The `Union` the method returns distinct elements from both arrays. Finally, `ToArray` is used to convert the result into an array. **Let us create a custom distinct and merge array function with two types.** ## 1. Create a Custom Generic Distinct function ```cs // Generic Method to return distinct elements from any array public static T[] DistinctArray(T[] array) { IList list = new List(); // Create a list to store distinct elements foreach (var item in array) { // Add item to list if it's not already present if (!list.Contains(item)) { list.Add(item); } } return list.ToArray(); // Convert list to array and return } ``` This function returns the unique values from any type of array. ## 2. Create a function to merge two arrays ## Using HashSet: ```cs // Merge arrays using HashSet public static T[] MergeArrayWithHashSet(T[] FirstArray, T[] SecondArray) { HashSet mergedSet = new HashSet(); // Create a HashSet to store merged elements foreach (var item in FirstArray) { mergedSet.Add(item); // Add elements of the first array to HashSet } foreach (var item in SecondArray) { mergedSet.Add(item); // Add elements of the second array to HashSet } T[] mergedArray = new T[mergedSet.Count]; // Create an array to store merged elements mergedSet.CopyTo(mergedArray); // Copy elements from HashSet to array return mergedArray; // Return merged array } ``` ## Using List : ```cs // Merge arrays using List public static T[] MergeArrayWithList(T[] FirstArray, T[] SecondArray) { IList data = new List(); // Create a list to store merged elements foreach (var item in FirstArray) { data.Add(item); // Add elements of the first array to list } foreach (var item in SecondArray) { data.Add(item); // Add elements of the second array to list } return DistinctArray(data.ToArray()); // Return array with distinct elements } ``` Let's merge the whole code into one program. ```cs using System; using System.Collections.Generic; using System.Linq; namespace ConsoleApp1 { class Program { static void Main(string[] args) { // Original arrays int[] FirstArray = { 1, 2, 3, 1, 2, 3, 1, 4, 12 }; int[] SecondArray = { 1, 22, 3, 1, 25, 3, 10, 4, 102 }; Console.WriteLine("Merge Array With HashSet"); // Merge arrays using HashSet int[] MergeArrayWithHashSet = Program.MergeArrayWithHashSet(FirstArray, SecondArray); foreach (var item in MergeArrayWithHashSet) { Console.Write(item + ", "); // Print each element of the merged array } Console.WriteLine("\n\nMerge Array With List"); // Merge arrays using List int[] MergeArrayWithList = Program.MergeArrayWithList(FirstArray, SecondArray); Console.Write(string.Join(", ", MergeArrayWithList)); // Print each element of the merged array Console.ReadLine(); } // Generic Method to return distinct elements from any array public static T[] DistinctArray(T[] array) { IList list = new List(); // Create a list to store distinct elements foreach (var item in array) { // Add item to list if it's not already present if (!list.Contains(item)) { list.Add(item); } } return list.ToArray(); // Convert list to array and return } // Merge arrays using HashSet public static T[] MergeArrayWithHashSet(T[] FirstArray, T[] SecondArray) { HashSet mergedSet = new HashSet(); // Create a HashSet to store merged elements foreach (var item in FirstArray) { mergedSet.Add(item); // Add elements of the first array to HashSet } foreach (var item in SecondArray) { mergedSet.Add(item); // Add elements of the second array to HashSet } T[] mergedArray = new T[mergedSet.Count]; // Create an array to store merged elements mergedSet.CopyTo(mergedArray); // Copy elements from HashSet to array return mergedArray; // Return merged array } // Merge arrays using List public static T[] MergeArrayWithList(T[] FirstArray, T[] SecondArray) { IList data = new List(); // Create a list to store merged elements foreach (var item in FirstArray) { data.Add(item); // Add elements of the first array to list } foreach (var item in SecondArray) { data.Add(item); // Add elements of the second array to list } return DistinctArray(data.ToArray()); // Return array with distinct elements } } } ``` ## Output: ![How to combine two arrays without duplicate values in C#?](https://www.mindstick.com/mindstickforums/6557aef8-fb48-4335-9fc3-32fc69afe304/images/e9b60267-c18a-4a30-a248-7528b6497f93.png) --- Original Source: https://www.mindstick.com/forum/160711/how-to-combine-two-arrays-without-duplicate-values-in-c-sharp Copyright © MindStick Software Pvt. Ltd. This Markdown version is provided for developers, AI systems, and offline reading.