c#: initialize a DateTime array

DateTime [] startDate = new DateTime[5];
       startDate[0] = new DateTime(11, 11, 10);
       startDate[1] = new DateTime(11, 11, 10);
       startDate[2] = new DateTime(11, 11, 10);
       startDate[3] = new DateTime(11, 11, 10);
       startDate[4] = new DateTime(11, 11, 10);

You mean like this?

DateTime[] dateTimes = new DateTime[]
{
    new DateTime(2010, 10, 1),
    new DateTime(2010, 10, 2),
    // etc
};

If you want to build an array for time span between two dates you could do something like this:

        timeEndDate = timeStartDate.AddYears(1); // or .AddMonts etc..
        rangeTimeSpan = timeEndDate.Subtract(timeStartDate); //declared prior as TimeSpan object
        rangeTimeArray = new DateTime[rangeTimeSpan.Days]; //declared prior as DateTime[]

        for (int i = 0; i < rangeTimeSpan.Days; i++)
        {
            timeStartDate = timeStartDate.AddDays(1);
            rangeTimeArray[i] = timeStartDate;
        }