New nullable type in. NET 2.0

In. NET 2.0, there is a new nullable type, which can be used to assign null values to the basic value type, such

Int? K = 3; // a value type that can be empty (empty for short)
Int M = NULL; // Error
Int? J = NULL; // success
From the above example, we can see that a value type that can be empty can be defined after the value type. in C #, is a value type added after the basic type? In VB. NET

DimDtmvarnameAsNullable (OfDatetime)

DimIntvarnameAsNullable (Of Integer)

DimBvarnameAsNullable (Of Boolean)

Note that the null type is not a new. NET data type.
In fact, the empty type is defined in the. Net Library as a type class system. nullable <t>, where T is the value type that can be replaced.
Int? K = 3; similarly, you can write system. nullable <int> K = 3;
The operations are implemented through the operator overloading of this class.

You can use hasvalue to determine whether the null type has been assigned a value.

If(Dtmvarname. hasvalue)

{

//... Do something

}