I cannot get the following function to work. A System.NullReferenceError
exception occurs when CopyMemory is executed. However, during debug I found
that none of the parameters passed are Null.
Is there a .NET way of doing this without using the CopyMemory API function?

Function ByteArrayToString(ByVal byteArray() As Byte, ByVal start As
Integer, ByVal length As Integer)
Dim temp As New String(Chr(0), length+1)
CopyMemory(temp, byteArray(start), length)
Return temp.ToString()
End Function

--
Thanks for any help,
Shayne H

Shayne,

Why not just use System.Text.Encoding.GetString(byte()) ?


Tim

Thanks Tim, will do.

I would be interested to know why my function had the exception.

"Tim" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Shayne,
>
> Why not just use System.Text.Encoding.GetString(byte()) ?
>
>
> Tim
>
>

On 2003-10-05, Shayne H <> wrote:
> I cannot get the following function to work. A System.NullReferenceError
> exception occurs when CopyMemory is executed. However, during debug I found
> that none of the parameters passed are Null.
> Is there a .NET way of doing this without using the CopyMemory API function?
>
> Function ByteArrayToString(ByVal byteArray() As Byte, ByVal start As
> Integer, ByVal length As Integer)
> Dim temp As New String(Chr(0), length+1)
> CopyMemory(temp, byteArray(start), length)
> Return temp.ToString()
> End Function
>
> --
> Thanks for any help,
> Shayne H
>
>
>
>

As was pointed out - don't use copymem for this - use the appropriate
System.Text.Encoding class for the job. In fact, using CopyMemory in
..NET is a little dangerous since objects can be relocated on the heap.
If you have to use it, you will want to pin the objects before the call
- basically you tell the runtime not to relocate them until I say it
is ok (look at the System.Runtime.InteropServices.GCHandle
structure, for more information)

But, to answer your question about the nullreference exception - well
with out seeing your declaration of CopyMemory - I would bet that it is
wrong. If you could post it, it would be easier to tell

Tom Shelton

Thanks Tom,

I used an overloaded declaration

Public Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" ( _
ByVal destination As Object, _
ByVal source As Object, _
ByVal length As Integer)

Public Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" ( _
ByVal destination As String, _
ByVal source As Object, _
ByVal length As Integer)

"Tom Shelton" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> On 2003-10-05, Shayne H <> wrote:
> > I cannot get the following function to work. A System.NullReferenceError
> > exception occurs when CopyMemory is executed. However, during debug I
found
> > that none of the parameters passed are Null.
> > Is there a .NET way of doing this without using the CopyMemory API
function?
> >
> > Function ByteArrayToString(ByVal byteArray() As Byte, ByVal start As
> > Integer, ByVal length As Integer)
> > Dim temp As New String(Chr(0), length+1)
> > CopyMemory(temp, byteArray(start), length)
> > Return temp.ToString()
> > End Function
> >
> > --
> > Thanks for any help,
> > Shayne H
> >
> >
> >
> >
>
> As was pointed out - don't use copymem for this - use the appropriate
> System.Text.Encoding class for the job. In fact, using CopyMemory in
> .NET is a little dangerous since objects can be relocated on the heap.
> If you have to use it, you will want to pin the objects before the call
> - basically you tell the runtime not to relocate them until I say it
> is ok (look at the System.Runtime.InteropServices.GCHandle
> structure, for more information)
>
> But, to answer your question about the nullreference exception - well
> with out seeing your declaration of CopyMemory - I would bet that it is
> wrong. If you could post it, it would be easier to tell
>
> Tom Shelton

"Shayne H" <shaynehATlycosSPAMGOTOHELLcoDOTuk> scripsit:
> I cannot get the following function to work. A System.NullReferenceError
> exception occurs when CopyMemory is executed. However, during debug I found
> that none of the parameters passed are Null.
> Is there a .NET way of doing this without using the CopyMemory API function?
>
> Function ByteArrayToString(ByVal byteArray() As Byte, ByVal start As
> Integer, ByVal length As Integer)
> Dim temp As New String(Chr(0), length+1)
> CopyMemory(temp, byteArray(start), length)
> Return temp.ToString()
> End Function

How do you declare 'CopyMemory'? Notice that strings are immutable and
cannot/should not be changed by unmanaged code. I would use
'System.Text.Encoding.*.GetString' methods.

--
Herfried K. Wagner
MVP · VB Classic, VB.NET
<http://www.mvps.org/dotnet>