Please check following code
DateTime? tmp = new DateTime();
tmp = null;
return tmp.ToString();
It returns String.Empty.
Is it correct?
May be it will be better to rise exception in second line of code
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1 Answer
Yes, it's correct. From the documentation
The text representation of the value of the current
Nullable<T>object if theHasValueproperty is true, or an empty string ("") if theHasValueproperty is false.
Note also that Nullable<T>.Equals and Nullable<T>.GetHashCode do not throw in this case but that Nullable<T>.GetType does throw. This is because Object.Equals, Object.GetHashCode and Object.ToString are overridden for Nullable<T> but that Object.GetType is not (because it can not be as it is not marked as virtual).
2 Comments
Andrei Andrushkevich
ok, thanks for you answer. but how you think is it correct way? because if you will use String tmp = null; tmp.ToString() it will rise exception
jason
Because a nullable type with
HasValue as false is not a null reference. From a conceptual perspective, a nullable type represents a value type with the possibility of the value being "missing." We use null to represent when the value is missing, but this is not the same as a null reference. Note that tmp.Value will throw in the case of tmp being an instance of a nullable type with HasValue as false. The value is missing so trying to obtain said value should and does throw accordingly.