Cannot access HasValue and Value Property of Nullable class

[Aamir Mahmood]

Hi

I am unable to access the HasValue and Value properties in an Nullable
object.

int? i = 9;
object value = i;
if ((value as Nullable).HasVa lue) {
...
}
It does not compile. VS2005 says "System.Nullabl e does not contain a
definition of HasValue".
I want to achieve this to make just one function which can handle various
nullables like int?, decimal?, long? etc.


However, following code compile and runs OK for me.

int? i = 9;
if (i.HasValue) {
...
}

MSDN Says:
Fundamental Properties:
The two fundamental members of the Nullable structure are the HasValue and
Value properties. If the HasValue property for a Nullable object is true,
the value of the object can be accessed with the Value property.

Any ideas?

Thanks.

AM

[Michael Starberg]

Re: Cannot access HasValue and Value Property of Nullable class


"Aamir Mahmood" <aamirmahmood@g mail.comwrote in message
news:eWqAFDPdIH A.1376@TK2MSFTN GP02.phx.gbl...

Hi
>
I am unable to access the HasValue and Value properties in an Nullable
object.
>
int? i = 9;
object value = i;
if ((value as Nullable).HasVa lue) {
...
}
It does not compile.

Of cource it won't.
You are way over your head..
... and have a lot of reading to do.

- Michael Starberg

[Michael Starberg]

Re: Cannot access HasValue and Value Property of Nullable class


"Peter Duniho" <NpOeStPeAdM@nn owslpianmk.comw rote in message
news:op.t6wkezg t8jd0ej@petes-computer.local. ..

I'd like to see you type on a keyboard. It must be of iron and go red hot.

Anyway, my reply was more effecient than yours, while we say pretty much the
same thing. =)
Mine might have been somewhat less helpful.. maybe...

- Michael Starberg

[Marc Gravell]

Re: Cannot access HasValue and Value Property of Nullable class

Nullable<Thas special boxing rules that return an empty Nullable<Tas a
null reference, rather than a boxed empty sruct. This means that everything
you need is as simple as testing your object variable for null, and
casting - i.e.

if(value != null) {
// ...
}

Marc

[Marc Gravell]

Re: Cannot access HasValue and Value Property of Nullable class

Minor addition for the OP; you need a constraint for that generic method to
compile:

public void DoSomething<T>( Nullable<Tpoten tialValue) where T : struct
{...}

Of course, this won't help if *all* you know is that you have an "object
value", since the compiler won't allow this usage...

Marc