Question

Possible Duplicate:
Type result with conditional operator in C#

I was just working on an a pop-up for modifying a user, when I ran into the following issue while attempting to modify the user’s Date of Death :

In this scenario, the property Death for the user is a DateTime? (Nullable Date Time).

user.Death = (model.Death != null) ? DateTime.Parse(model.Death) : null;

So I figured that I would be able to simply check if the value contained in the model (model.Death is a string) contained a value, I would set the date that value, otherwise I would set it to null, as demonstrated above.

However, I was unable to use this syntax, as it would not allow me to explicitly set user.Death to null, using the ternary operator, although user.Death = null worked just fine.

Solution used :

Replaced : null with : new Nullable<DateTime>()

I guess I am just wondering, why was I unable to explicitly set a Nullable DateTime property to null using a ternary operator?

Answer 1

This doesn’t work because the compiler will not insert an implicit conversion on both sides at once.

You want the compiler to convert a DateTime value to DateTime? on one side, and null to DateTime? on the other side.
This cannot happen.

If you explicitly convert either half to DateTime?, the other half will implicitly convert too.