How to combine two arrays without duplicate values in C#?

Steilla Mitchel 2113 11 Jun 2024

Ask by Steilla Mitchel

Updated 11 Jun 2024

1 Answers

Ravi Vishwakarma 11 Jun 2024

One way to combine two arrays without duplicate values in C# is to use LINQ and the Union method.

Here's how you can do it:

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

        // Generic Method to return distinct elements from any array
        public static T[] DistinctArray<T>(T[] array)
        {
            IList<T> list = new List<T>(); // 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<T>(item))
                {
                    list.Add(item);
                }
            }

            return list.ToArray<T>(); // 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:

        // Merge arrays using HashSet
        public static T[] MergeArrayWithHashSet<T>(T[] FirstArray, T[] SecondArray)
        {
            HashSet<T> mergedSet = new HashSet<T>(); // 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 :

        // Merge arrays using List
        public static T[] MergeArrayWithList<T>(T[] FirstArray, T[] SecondArray)
        {
            IList<T> data = new List<T>(); // 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<T>(data.ToArray()); // Return array with distinct elements
        }

Let's merge the whole code into one program.

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<int>(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<int>(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>(T[] array)
        {
            IList<T> list = new List<T>(); // 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<T>(item))
                {
                    list.Add(item);
                }
            }

            return list.ToArray<T>(); // Convert list to array and return
        }

        // Merge arrays using HashSet
        public static T[] MergeArrayWithHashSet<T>(T[] FirstArray, T[] SecondArray)
        {
            HashSet<T> mergedSet = new HashSet<T>(); // 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>(T[] FirstArray, T[] SecondArray)
        {
            IList<T> data = new List<T>(); // 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<T>(data.ToArray()); // Return array with distinct elements
        }
    }
}

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