How about this?
public static class ExtendDateTime
public int CountWeekDays(this DateTime thisdate, DateTime thatDate)
int days = Math.Abs((thisDate - thatDate).Days) + 1;
return = ((days/7) * 5) + (days % 7);
Usage would be like this:
DateTime startDate = new DateTime(2011, 11, 1);
int weekdays = startDate.CountWeekDays(new DateTime(2011, 11, 30));
BTW, if you haven't noticed, this extension method works whether the date being compared occurs in the future OR in the past.
I've been paid as a programmer since 1982 with experience in Pascal, and C++ (both self-taught), and began writing Windows programs in 1991 using Visual C++ and MFC. In the 2nd half of 2007, I started writing C# Windows Forms and ASP.Net applications, and have since done WPF, Silverlight, WCF, web services, and Windows services.
My weakest point is that my moments of clarity are too brief to hold a meaningful conversation that requires more than 30 seconds to complete. Thankfully, grunts of agreement are all that is required to conduct most discussions without committing to any particular belief system.