The following code implements the in VB (C# is a little further down the page):

Imports System

Imports System.Collections.Generic

Imports System.Text

Imports System.Diagnostics

'Sieve of Eratosthenes

 

 

Public Class PrimeSieve

 

    Private values As Numbers()

 

    Public Sub New(ByVal max As Integer)

        ReDim values(max)

    End Sub

 

    Public Function ComputePrimes() As TimeSpan

        Dim sw As Stopwatch = New Stopwatch

        values(0) = Numbers.Prime

        'not really... but, it helps

        values(1) = Numbers.Prime

        sw.Start()

        'Loop through each unset value

        Dim outer As Integer = 2

        Do While (outer <> -1)

            'The next unset value must be prime

            values(outer) = Numbers.Prime

            Console.WriteLine(outer)

            'mark out all multiples of this prime as being Composite

            Dim inner As Integer = (outer * 2)

            Do While (inner < values.Length)

                values(inner) = Numbers.Composite

                inner = (inner + outer)

            Loop

            outer = FirstUnset(outer)

        Loop

        sw.Stop()

        Return sw.Elapsed

    End Function

 

    Function FirstUnset(ByVal last As Integer) As Integer

        Dim i As Integer = last

        Do While (i < values.Length)

            If (values(i) = Numbers.Unset) Then

                Return i

            End If

            i = i + 1

        Loop

        Return -1

    End Function

 

End Class

 

Public Enum Numbers

 

    Unset

    Prime

    Composite

End Enum

Module Module1

 

    Sub Main()

        Dim ps As PrimeSieve = New PrimeSieve(100000)

        Dim ts As TimeSpan = ps.ComputePrimes

        Console.WriteLine("Complete: {0}", ts)

        Console.ReadLine()

    End Sub

End Module

 

The following code implements the in C#:

using System;

using System.Collections.Generic;

using System.Text;

using System.Diagnostics;

 

//Sieve of Eratosthenes

namespace Samples

{

    public class PrimeSieve : IEnumerable<int>

    {

        Numbers[] values;

        public PrimeSieve(int max)

        {

            values = new Numbers[max];

        }

        public TimeSpan ComputePrimes()

        {

            Stopwatch sw = new Stopwatch();

            values[0] = Numbers.Prime; //not really... but, it helps

            values[1] = Numbers.Prime;

 

            sw.Start();

            //Loop through each unset value

            for (int outer = 2; outer != -1; outer = FirstUnset(outer))

            {

                //The next unset value must be prime

                values[outer] = Numbers.Prime;

                //mark out all multiples of this prime as being Composite

                for (int inner = outer*2; inner < values.Length; inner += outer)

                {

                    values[inner] = Numbers.Composite;

                }

            }

            sw.Stop();

            return sw.Elapsed;

        }

        int FirstUnset(int last)

        {

            for (int i = last; i < values.Length; i++)

            {

                if (values[i] == Numbers.Unset) return i;

            }

            return -1;

        }

 

        System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()

        {

            return GetEnumerator();

        }

        public IEnumerator<int> GetEnumerator()

        {

            for (int i = 2; i < values.Length; i++)

            {

                if (values[i] == Numbers.Prime) yield return i;

            }

        }

    }

    public enum Numbers

    {

        Unset,

        Prime,

        Composite,

    }

 

    class Program

    {

 

        static void Main(string[] args)

        {

            PrimeSieve ps = new PrimeSieve(100000000);

            TimeSpan ts = ps.ComputePrimes();

            foreach (int i in ps)

            {

                Console.WriteLine(i);

            }

            Console.WriteLine("Complete: {0}", ts);

 

            List<int> l = new List<int>();

            int last = 0;

            foreach (int i in ps)

            {

                l.Add(Math.Abs(last - i));

                last = i;

            }

 

            double sum = 0.0;

            double sumOfSqrs = 0.0;

            l.ForEach(delegate(int value)

            {

                sum += value;

                sumOfSqrs += Math.Pow(value, 2);

            });

            double n = (double)l.Count;

            double topSum = (n * sumOfSqrs) - (Math.Pow(sum, 2));

            double standardDeviation = Math.Sqrt(topSum / (n * (n - 1)));

            Console.WriteLine("Average: {0:##.##}", sum / n);

            Console.WriteLine("Standard Deviation {0}", standardDeviation);

            Console.ReadLine();

        }

    }

}