var result = arr1.Concat(arr2);

using System;
using System. Collections;
using System.Collections.Generic;
using System. Linq;
using System. Text;
using System.Threading.Tasks;

namespace ConsoleApp1
{
    class Programme2
    {
        static void Main(string[] args)
        {
//here we create two array type of string variable array1 and array2 
            string[] array1 = { "a", "b", "c", "d" };

            string[] array2 = { "c", "d", "e", "f" };
/*here we will concat two array with the help of 'concat'
    method and store the output in 'result' variable*/
            var result = array1.Concat(array2);
//foreach loop will print the value of result
            foreach (var item in result)

            {

                Console.WriteLine(item);
            }

            Console.ReadLine();

        }

    }

    }