Problem
I’ve been searching a lot but couldn’t find a solution. How do you deal with a DateTime that should be able to contain an uninitialized value (equivalent to null)? I have a class which might have a DateTime property value set or not. I was thinking of initializing the property holder to DateTime.MinValue, which then could easily be checked. I guess this is a quite common question, how do you do that?
Asked by Mats
Solution #1
For normal DateTimes, if you don’t initialize them at all then they will match DateTime.MinValue, because it is a value type rather than a reference type.
You can also use a DateTime that is nullable, such as this:
DateTime? MyNullableDate;
Alternatively, you can use the longer form:
Nullable<DateTime> MyNullableDate;
Finally, there’s a built-in way to refer to any type’s default. For reference types, this returns null, however for our DateTime example, it will return DateTime. MinValue:
default(DateTime)
or, if you’re using a more modern version of C#,
default
Answered by Joel Coehoorn
Solution #2
You can use the nullable type if you’re using.NET 2.0 (or later):
DateTime? dt = null;
or
Nullable<DateTime> dt = null;
then later:
dt = new DateTime();
You can also double-check the value with:
if (dt.HasValue)
{
// Do something with dt.Value
}
You can also use it like this:
DateTime dt2 = dt ?? DateTime.MinValue;
More information is available at http://msdn.microsoft.com/en-us/library/b3h38hb0.aspx.
Answered by Mark Ingram
Solution #3
It is also possible to use the following method.
myClass.PublishDate = toPublish ? DateTime.Now : (DateTime?)null;
Please keep in mind that the PublishDate property should be a DateTime?
Answered by Aleksei
Solution #4
DateTime? MyDateTime{get;set;}
MyDateTime = (dr["f1"] == DBNull.Value) ? (DateTime?)null : ((DateTime)dr["f1"]);
Answered by Iman
Solution #5
I’d think about utilizing nullable types.
Instead of DateTime myDate, use myDate.
Answered by David Mohundro
Post is based on https://stackoverflow.com/questions/221732/datetime-null-value