using System;

using System.Collections;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {   

        var startDate = new DateTime(2016, 10, 1); 

        var endDate = new DateTime(2016, 10, 5);

        var range = new DateRange(startDate, endDate);

        foreach(var date in range)

        {

            Console.WriteLine(date.ToString("dd/MM/yyyy") + " - Days From Start: " + range.DaysFromStart((date)));

        }           

    }

}

​

//Clase que representa un rango de fechas

public class DateRange : IEnumerable<DateTime>

{

    private readonly DateTime _start;

    private readonly DateTime _end;

​

    public DateRange(DateTime start, DateTime end)

    {

        _start = start;

        _end = end;

    }

    public DateTime Start { get { return _start;} }

    public DateTime End { get { return _end; } }

​

    public bool Includes(DateTime date)

    {

        return date >= Start && date <= End;

    }

    IEnumerator IEnumerable.GetEnumerator()

    {

        return GetEnumerator();

    }

​

    public IEnumerator<DateTime> GetEnumerator()

    {

        for (var d = Start; d <= End; d = d.AddDays(1))

        {

            yield return d;

        }

    }

    public int DaysFromStart(DateTime date)

    {

        return (date - Start).Days;

    }

}

​