c# - Find TotalDays between two Datetime? variables

Question

   DateTime? arrival = (DateTime?)(t.ArrivalDate.Value);
   DateTime? departure = (DateTime?)(t.DepartureDate);

Okay i know both of them are nullable and .TotalDays does not work on nullable object. So kindly tell me how am i supposed to find days difference between these two objects.

Note: Both objects contains Date(s) i.e. are not null

Answer 1

如果它们中的任何一个为空，则它们的差异没有有意义的价值，因此您只需要关注它们不存在的情况：

DateTime? arrival = (DateTime?)(t.ArrivalDate.Value);
DateTime? departure = (DateTime?)(t.DepartureDate);
double? totalDays = arrival.HasValue && departure.HasValue 
   ? (double?)(departure - arrival).GetValueOrDefault().TotalDays
   : null;

由于隐式转换为 ，减法应该起作用DateTime。

Answer 2

注意：两个对象都包含日期，即不为空

如果您确定日期永远不会为 null，那么您可以将 .Value 用于可为空的 DateTime 对象。当其中任何一个为空时，您将获得异常。

double days = departure.Value.Subtract(arrival.Value).TotalDays;

Answer 3

    //Set dates
    DateTime? beginDate = DateTime.Now;
    DateTime? endDate = DateTime.Now.AddDays(10);

    //Check both values have a value (they will based on above)
    //If they do get the ticks between them
    long diff = 0;
    if (beginDate.HasValue && endDate.HasValue)
        diff = endDate.Value.Ticks - beginDate.Value.Ticks;

    //Get difference in ticks as a time span to get days between.
    int daysDifference =  new TimeSpan(diff).Days;

Answer 4

这里我给你测试过的代码请看一下：

 DateTime? startDate = DateTime.Now;
        DateTime? endDate = DateTime.Now.AddDays(5);


        long differenceOfDays = 0;
        if (startDate.HasValue && endDate.HasValue)
            differenceOfDays = endDate.Value.Ticks - startDate.Value.Ticks;

        int daysDifference = new TimeSpan(differenceOfDays).Days;