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How to Combine Two Arrays without Duplicate values in C#?

  • Last Updated : 01 Nov, 2021

Given two arrays, now our task is to merge or combine these arrays into a single array without duplicate values. So we can do this task using the Union() method. This method combines two arrays by removing duplicated elements in both arrays. If two same elements are there in an array, then it will take the element only once.

Syntax:

first_array.Union(second_array)

Examples:

Input  : array1 = {22, 33, 21, 34, 56, 32}
         array2 = {24, 56, 78, 34, 22}
Output : New array = {22, 33, 21, 34, 56, 32, 24, 78}

Input  : array1 = {1}
         array2 = {2}
Output : New array = {1, 2}

Approach

1. Declare two arrays of any type integer, string, etc.

2. Apply Union() function and convert to array using ToArray() function.

final = array1.Union(array2).ToArray();

3. Now iterate the elements in the final array using ForEach() function.

Array.ForEach(final, i => Console.WriteLine(i));

4. We can also iterate the array using IEnumerable method.

IEnumerable<int> final = array1.Union(array2);    
foreach (var in final)    
{    
    Console.WriteLine(i);    
} 

Example 1: 

C#




// C# program to merge two array into a single
// array without duplicate elements
using System;
using System.Collections.Generic;
using System.Linq;
  
class GFG{
  
public static void Main()
{
      
    // Declare first array with integer numbers
    int[] array1 = { 22, 33, 21, 34, 56, 32 };
      
    // Declare second array with integer numbers
    int[] array2 = { 24, 33, 21, 34, 22 };
      
    // Displaying array 1
    Console.WriteLine("Array 1: ");
      
    foreach (int x1 in array1)
    {
        Console.WriteLine(x1);
    }
      
    // Displaying array 2
    Console.WriteLine("Array 2: ");
      
    foreach (int x2 in array2)
    {
        Console.WriteLine(x2);
    }
      
    // Combine the unique elements and convert into array
    var final = array1.Union(array2).ToArray();
      
    // Display the elements in the final array
    Console.WriteLine("New array:");
    Array.ForEach(final, i => Console.WriteLine(i));
}
}

Output:

Array 1: 
22
33
21
34
56
32
Array 2: 
24
33
21
34
22
New array:
22
33
21
34
56
32
24

Example 2: 

C#




// C# program to merge two array into a single
// array without duplicate elements
using System;
using System.Collections.Generic;
using System.Linq;
                      
class GFG{
  
public static void Main()
{
      
    // Declare first array with strings 
    string[] array1 = { "ojaswi", "gnanesh", "bobby" };    
      
    // Declare second array with also strings
    string[] array2 = { "rohith", "ojaswi", "bobby" };
      
    // Displaying array 1
    Console.WriteLine("Array 1: ");
      
    foreach (string x1 in array1)
    {
        Console.WriteLine(x1);
    }
      
    // Displaying array 2
    Console.WriteLine("\nArray 2: ");
      
    foreach (string x2 in array2)
    {
        Console.WriteLine(x2);
    }
      
    // Combine the unique elements and convert into array
    IEnumerable<string> final1 = array1.Union(array2); 
      
    Console.WriteLine("\nNew array:");
      
    // Display the elements in the final array
    foreach (var j in final1)    
    {    
        Console.WriteLine(j);    
    
}
}

Output:

Array 1: 
ojaswi
gnanesh
bobby

Array 2: 
rohith
ojaswi
bobby

New array:
ojaswi
gnanesh
bobby
rohith

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