using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        var startDate = new DateTime(2015, 7, 1);

        var endDate = new DateTime(2015, 9, 1);

        var workDates = Enumerable.Range(0, (int)(endDate - startDate).TotalDays + 1)

            .Select(i => startDate.AddDays(i))

            .Where(date => (date.DayOfWeek != DayOfWeek.Saturday && date.DayOfWeek != DayOfWeek.Sunday))

            .Select(i => i);

        var display = workDates

            .GroupAdjacentBy((x, y) => x.AddDays(1) == y)

            .Select(g => string.Format("Start: {0:dd/MMM/yyyy} End: {1:dd/MMM/yyy}", g.First(), g.Last()));

        foreach (var displayString in display)

        {

            Console.WriteLine(displayString);

        }

    }

}

​

public static class IEnumerableExtension

{

    public static IEnumerable<IEnumerable<T>> GroupAdjacentBy<T>(

        this IEnumerable<T> source, Func<T, T, bool> predicate)

    {

        using (var e = source.GetEnumerator())

        {

            if (e.MoveNext())

            {

                var list = new List<T> { e.Current };

                var pred = e.Current;

                while (e.MoveNext())

                {

                    if (predicate(pred, e.Current))

                    {

                        list.Add(e.Current);

                    }

                    else

                    {

                        yield return list;

                        list = new List<T> { e.Current };

                    }

                    pred = e.Current;

                }

                yield return list;

            }

        }

    }

}