在双数组中获取给定日期的第一个日期索引

你可以试试:

DateTime tocheck = new DateTime();
tocheck = DateTime.Parse("27-July-2018 12:15:00");
double tochkd = tocheck.ToOADate();

int index = dateDouble.IndexOf(dateDouble.FirstOrDefault(x => (int)x == (int)tochkd));

或者你也可以这样做

int index = dateDouble.IndexOf(dateDouble.FirstOrDefault(x => (int)x == tocheck.Date.ToOADate());

输出:

   result = 1

如果该值存在,它将返回索引,否则它将返回-1

试试这个:

List<DateTime> dt = new List<DateTime>
{
    new DateTime(2018,7,26,14,0,0),// 26-July-2018 14:00:00
    new DateTime(2018,7,27,12,9,0),//27 - July - 2018 12:09:00
    new DateTime(2018,7,27,12,10,0),//27 - July - 2018 12:10:00
    new DateTime(2018,7,27,12,15,0),//27 - July - 2018 12:15:00
    new DateTime(2018,7,28,12,50,0),//28 - July - 2018 12:50:00
    new DateTime(2018,7,28,13,40,0)//28 - July - 2018 13:40:00
};

List<double> dbl = dt.Select(d => d.ToOADate()).ToList();
DateTime startDate = new DateTime(2018, 7, 27, 12, 15, 0);
double startDateDbl = (new DateTime(startDate.Year, startDate.Month, startDate.Day, 0, 0, 0)).ToOADate();
List<double> filteredDates = dbl.Where(d => d >= startDateDbl).ToList();