using System;

public class Program

{

        static void ChangeByReference1(ref double[] arr)

        {

            arr = new double[5];

            for (int i = 0; i < arr.Length; i++)

                arr[i] = i;

        }

        static void ChangeByReference2(double [] arr)

        {

            arr = new double[5];

            for (int i = 0; i < arr.Length; i++)

                arr[i] = i;

        }

        static void ChangeByReference3(double[] arr)

        {

            for (int i = 0; i < arr.Length; i++)

                arr[i] = i;

            arr = new double[5];

        }

        static void ChangeByReference4(ref double[] arr)

        {

            for (int i = 0; i < arr.Length; i++)

                arr[i] = i;

            arr = new double[5];

        }

​

        public static void Main(string[] args)

        {

            var arr1 = new[] { 0.1, 0.2, 0.3 };

            var arr2 = new[] { 0.1, 0.2, 0.3 };

            var arr3 = new[] { 0.1, 0.2, 0.3 };

            var arr4 = new[] { 0.1, 0.2, 0.3 };

​

            ChangeByReference1(ref arr1);

            ChangeByReference2(arr2);

            ChangeByReference3(arr3);

            ChangeByReference4(ref arr4);

​

            Console.WriteLine("arr1\n{0}\n", string.Join("\t", arr1));

            Console.WriteLine("arr2\n{0}\n", string.Join("\t", arr2));

            Console.WriteLine("arr3\n{0}\n", string.Join("\t", arr3));

            Console.WriteLine("arr4\n{0}\n", string.Join("\t", arr4));

​

        }

}