Nullable DateTime in C#

Question

I have two questions related to DateTime assingments

DateTime? y = 1 == 1 ? null: DateTime.MaxValue;
DateTime? y = null; // assignment works as expected

• Why the first assignment issues error of type conversion between null and DateTime?

• Which is the preferred way for null assignments of DateTime? in c#.

  DateTime? x = default(DateTime?); //prints null on console
  
  DateTime? x = null;               // prints null on console
  
  DateTime? x = DateTime.MinValue;  //print 01/01/0001 
  

Answer 1

The second statement DateTime? y = null; is only an assignment of null to a nullable object.

Whereas the first is a conditional assignment, which assigns some value for the true state and some other value for the false; Here you are using the conditional operator for evaluating the condition. according to MSDN first_expression (executes if true) and second_expression*(executes if false)* must be of same type or an implicit conversion must exist from one type to the other. In our case both are different so The simple solution is doing an explicit conversion as like this:

DateTime? y = 1 == 1 ?(DateTime?) null : DateTime.MaxValue;