Pass a structure by reference to C++ dll in .Net Compact Framework

[Maloney]

I'm trying to pass a structer from C# to a C dll in .Net Compact Framework

This partially works. If in the GetStatus I only set -- status->fileLength
= 10; -- and not the second variable then filelength = 10 and fileposition =
0, but if i set the second one only or both of them then they are fileLength
= 47244640266 and filePosition = 0; Like the memory is getting over wrote.
What is the correct way of passing a structure by reference on the Compact
Framework.

here is my code

In the C dll
-------------------------------------------

----------------in the header
struct FileStatus
{
long fileLength;
long filePosition;
};

extern "C" __declspec(dlle xport) bool GetStatus (FileStatus* status);
----------------

---------------in the cpp
bool GetStatus (FileStatus* status)
{
status->fileLength = 10;
status->filePosition = 11;
return true;
}
--------------------------------------------

int my C# code i have
--------------------------------------------
namespace Controls
{
[StructLayout(La youtKind.Sequen tial)]
public struct SStatus
{
public long fileLength;
public long filePosition;
}
public class VitoSoundExplor er
{

[DllImport("Test Dll.dll", EntryPoint="Get Status")]
public static extern bool GetStatus(ref SStatus status);


public bool GetStatus()
{
SStatus st= new SStatus();
GetStatus(ref st);
return true;
}
}
}
------------------------------------------

Any Ideas

thanks

[Lloyd Dupont]

Re: Pass a structure by reference to C++ dll in .Net Compact Framework

since when a long in C is 8 bytes long ?
maybe on windows 64, but certainly not on PPC, or so I assume....

I would rather write:
[StructLayout(La youtKind.Sequen tial)]
public struct SStatus
{
public int fileLength;
public int filePosition;
}

"Maloney" <sabrogden@soft home.net> wrote in message
news:OfFSUNUiDH A.3032@tk2msftn gp13.phx.gbl...[color=blue]
> I'm trying to pass a structer from C# to a C dll in .Net Compact Framework
>
> This partially works. If in the GetStatus I only set --[/color]
status->fileLength[color=blue]
> = 10; -- and not the second variable then filelength = 10 and fileposition[/color]
=[color=blue]
> 0, but if i set the second one only or both of them then they are[/color]
fileLength[color=blue]
> = 47244640266 and filePosition = 0; Like the memory is getting over[/color]
wrote.[color=blue]
> What is the correct way of passing a structure by reference on the Compact
> Framework.
>
> here is my code
>
> In the C dll
> -------------------------------------------
>
> ----------------in the header
> struct FileStatus
> {
> long fileLength;
> long filePosition;
> };
>
> extern "C" __declspec(dlle xport) bool GetStatus (FileStatus* status);
> ----------------
>
> ---------------in the cpp
> bool GetStatus (FileStatus* status)
> {
> status->fileLength = 10;
> status->filePosition = 11;
> return true;
> }
> --------------------------------------------
>
> int my C# code i have
> --------------------------------------------
> namespace Controls
> {
> [StructLayout(La youtKind.Sequen tial)]
> public struct SStatus
> {
> public long fileLength;
> public long filePosition;
> }
> public class VitoSoundExplor er
> {
>
> [DllImport("Test Dll.dll", EntryPoint="Get Status")]
> public static extern bool GetStatus(ref SStatus status);
>
>
> public bool GetStatus()
> {
> SStatus st= new SStatus();
> GetStatus(ref st);
> return true;
> }
> }
> }
> ------------------------------------------
>
> Any Ideas
>
> thanks
>
>[/color]

[Lloyd Dupont]

Re: Pass a structure by reference to C++ dll in .Net Compact Framework

FYI:
here is the whole story, I believe:
C:
char: 1 bytes
short: 2 bytes
long: 4 bytes
long long (gcc): 8 bytes
int: size of register (4 on PPC)

C#:
int: 4 bytes
long: 8 bytes
see ?

"Maloney" <sabrogden@soft home.net> wrote in message
news:OfFSUNUiDH A.3032@tk2msftn gp13.phx.gbl...[color=blue]
> I'm trying to pass a structer from C# to a C dll in .Net Compact Framework
>
> This partially works. If in the GetStatus I only set --[/color]
status->fileLength[color=blue]
> = 10; -- and not the second variable then filelength = 10 and fileposition[/color]
=[color=blue]
> 0, but if i set the second one only or both of them then they are[/color]
fileLength[color=blue]
> = 47244640266 and filePosition = 0; Like the memory is getting over[/color]
wrote.[color=blue]
> What is the correct way of passing a structure by reference on the Compact
> Framework.
>
> here is my code
>
> In the C dll
> -------------------------------------------
>
> ----------------in the header
> struct FileStatus
> {
> long fileLength;
> long filePosition;
> };
>
> extern "C" __declspec(dlle xport) bool GetStatus (FileStatus* status);
> ----------------
>
> ---------------in the cpp
> bool GetStatus (FileStatus* status)
> {
> status->fileLength = 10;
> status->filePosition = 11;
> return true;
> }
> --------------------------------------------
>
> int my C# code i have
> --------------------------------------------
> namespace Controls
> {
> [StructLayout(La youtKind.Sequen tial)]
> public struct SStatus
> {
> public long fileLength;
> public long filePosition;
> }
> public class VitoSoundExplor er
> {
>
> [DllImport("Test Dll.dll", EntryPoint="Get Status")]
> public static extern bool GetStatus(ref SStatus status);
>
>
> public bool GetStatus()
> {
> SStatus st= new SStatus();
> GetStatus(ref st);
> return true;
> }
> }
> }
> ------------------------------------------
>
> Any Ideas
>
> thanks
>
>[/color]