Question

I am stuck for sometime now, now need your help.

I want to display in a dropdown only fourth Sunday of each month, say from 1-Sep-2010 to 31-Aug-2011

I only want fourth Sunday in dropdown list, how to do it using asp.net C#

Regards

Answer 1

Here is an approach that uses a little LINQ and the knowledge that the fourth Sunday will occur between the 22nd and 28th of a month, inclusive.

DateTime startDate = new DateTime(2010, 9, 1);
DateTime endDate = startDate.AddYears(1).AddDays(-1);

List<DateTime> fourthSundays = new List<DateTime>();

DateTime currentDate = startDate;
while (currentDate < endDate)
{
    // we know the fourth sunday will be the 22-28
    DateTime fourthSunday = Enumerable.Range(22, 7).Select(day => new DateTime(currentDate.Year, currentDate.Month, day)).Single(date => date.DayOfWeek == DayOfWeek.Sunday);
    fourthSundays.Add(fourthSunday);
    currentDate = currentDate.AddMonths(1);
}

You can then bind that List<DateTime> to the dropdown or skip the list itself in favor of adding the items as you generate them to the dropdown, like below.

yourDropdown.Items.Add(new ListItem(fourthSunday.ToString()));

For giggles, you can do the whole thing in a LINQ statement and skip (most of) the variables.

DateTime startDate = new DateTime(2010, 9, 1); 
IEnumerable<DateTime> fourthSundays =
    Enumerable.Range(0, 12)
    .Select(item => startDate.AddMonths(item))
    .Select(currentMonth =>
        Enumerable.Range(22, 7)
        .Select(day => new DateTime(currentMonth.Year, currentMonth.Month, day))
        .Single(date => date.DayOfWeek == DayOfWeek.Sunday)
    );