C# supports pointer.

27 Jun 2005 5:46 PM

Rulin Hong

What do we do for pointer in VB.NET?

Thanks

27 Jun 2005 6:03 PM

Herfried K. Wagner [MVP]

"Rulin Hong" <RulinH***@discussions.microsoft.com> schrieb:
> What do we do for pointer in VB.NET?

C# supports pointers only inside 'unsafe' blocks which are only useful in
some very rare cases. VB.NET gladly doesn't support them. What do you want
to archieve?

--
M S Herfried K. Wagner
M V P <URL:http://dotnet.mvps.org/>
V B <URL:http://classicvb.org/petition/>

27 Jun 2005 6:05 PM

Crouchie1998

Dim ptr As IntPtr

Crouchie1998
BA (HONS) MCP MCSE

27 Jun 2005 6:39 PM

Armin Zingler

"Crouchie1998" <crouchie1998@spamcop.net> schrieb
> Dim ptr As IntPtr

hehe. :-))

Armin

27 Jun 2005 10:41 PM

Mike Labosh

>> Dim ptr As IntPtr
>
> hehe. :-))

You guys are *evil*. Let me see some VB.NET code that dereferences ptr and
I'll be impressed.

--
Peace & happy computing,

Mike Labosh, MCSD

"Mr. McKittrick, after very careful consideration, I have
come to the conclusion that this new system SUCKS."
-- General Barringer, "War Games"

28 Jun 2005 12:29 AM

Armin Zingler

"Mike Labosh" <mlab***@hotmail.com> schrieb
> > > Dim ptr As IntPtr
> >
> > hehe. :-))
>
> You guys are *evil*. Let me see some VB.NET code that dereferences
> ptr and I'll be impressed.

dim b(499) as byte
Marshal.Copy(ptr, b, 0, 500)

msgbox b(17) 'reference to b(17)

;-)

Armin

28 Jun 2005 2:03 PM

Jay B. Harlow [MVP - Outlook]

Mike,
As Armin suggests, there are a number of methods on
System.Runtime.InteropServices.Marshal class that allows you to dereference
an IntPtr.

Marshal.Read* & Marshal.Write* may be "better" to use then Marshal.Copy. I
find Marshal.PtrToStructure & Marshal.StructureToPtr to be extremely useful
in some interop cases.

Of course Marshal.PtrToString* & Marshal.StringTo* are invaluable when
dealing with strings.

I've even used Marshal.GetObjectForIUnknown once or twice...

Hope this helps
Jay

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28 Jun 2005 11:13 AM

Dragon

Hello Rulin,

If you have an variable and you want its address:
~
Dim GCH as GCHandle = GCHandle.Alloc(YourVar, GCHandleType.Pinned)
REM now GCH.AddrOfPinnedObject is pointer to your var so do whatever you
want
GCH.Free()
~

On the other hand, if you have an address, you can get a value:
~
DesiredValue = CType(Marshal.PtrToStructure(YourPointer,
DesiredValue.GetType), TypeOfDesiredValue)
~
Note that this time you actually get COPY of the value.

Marshal and GCHandle are located in System.Runtime.InteropServices
namespace.

Hope this helps

Dragon

"Rulin Hong" <RulinH***@discussions.microsoft.com> ÓÏÏÂÝÉÌ/ÓÏÏÂÝÉÌÁ ×

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news:46643BD9-8CD2-4085-B1C9-F26CD1F6DFB0@microsoft.com...
> What do we do for pointer in VB.NET?
>
> Thanks