using System;

using System.Collections.Generic;

using System.Linq;

using System.Diagnostics;

public class Program

{

    public static void Main()

    {

        int[] array = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, 16, 17, 18, 19};

        Stopwatch s1 = new Stopwatch();

        Stopwatch s2 = new Stopwatch();

        Stopwatch s3 = new Stopwatch();

        Stopwatch s4 = new Stopwatch();

        const int iterations = 10000;

        for (int i = 0; i < iterations; i++)

        {

            s1.Start();

            int[] result = ConvertToListAndBack(array, 2);

            s1.Stop();

            s2.Start();

            int[] result2 = array.RemoveAt(2);

            s2.Stop();

            s3.Start();

            int[] result3 = RemoveIndices(array, 2);

            s3.Stop();

​

            s4.Start();

            int[] result4 = LinqSolution(array, 2);

            s4.Stop();

        }

        Console.WriteLine("Elapsed time after " + iterations + " iterations:");

        Console.WriteLine("Convert to List, use RemoveAt(): " + s1.Elapsed);

        Console.WriteLine("RemoveAt extension method: " + s2.Elapsed);

        Console.WriteLine("RemoveIndices method: " + s3.Elapsed);

        Console.WriteLine("LINQ solution: " + s4.Elapsed);

    }

    private static int[] ConvertToListAndBack(int[] array, int removeAt)

    {

        var foos = new List<int>(array);

        foos.RemoveAt(removeAt);

        return foos.ToArray();

    }

    private static int[] RemoveIndices(int[] IndicesArray, int RemoveAt)

    {

        int[] newIndicesArray = new int[IndicesArray.Length - 1];

        int i = 0;

        int j = 0;

        while (i < IndicesArray.Length)

        {

            if (i != RemoveAt)

            {

                newIndicesArray[j] = IndicesArray[i];

                j++;

            }

            i++;

        }

        return newIndicesArray;

    }

    private static int[] LinqSolution(int[] array, int removeAt)

    {

        int[] result = array.Where((source, index) => index != removeAt).ToArray();

        return result;

    }

}

​

public static class ExtensionMethods

{

    public static T[] RemoveAt<T>(this T[] source, int index)

    {

        T[] dest = new T[source.Length - 1];

        if( index > 0 )

            Array.Copy(source, 0, dest, 0, index);

        if( index < source.Length - 1 )

            Array.Copy(source, index + 1, dest, index, source.Length - index - 1);

        return dest;

    }

}