I am something of a newbie in the world of C# data structures, but I am
writing an application that needs to call a legacy DLL using .net 1.1. That
is no big deal mostly, but I am having trouble with one function. It is
defined in the original C as

UINT32 __stdcall GetState(
UINT32 timeout,
UINT32 client_id,
void *status_array
);

status is defines as a pointer to 64 status records (structs) they are
defined as

typedef struct status_rec {
UINT32 type;
UINT32 state;
UINT32 version;
UINT32 flags;
CHAR ip_address[15];
CHAR filler[9];
} status, *p_status

I defined this in C# as

[StructLayout=LayoutType.Sequential, Pack=1, CharSet = CharSet.Ansii]
public struct status_rec {
public UINT32 type;
public UINT32 state;
public UINT32 version;
public UINT32 flags;
[MarshalAs(UnmanagedType.ByValArray, ArraySubType = UnmanagedType.U1,
SizeConst=15)]
public CHAR ip_address[15];
[MarshalAs(UnmanagedType.ByValArray, ArraySubType = UnmanagedType.U1,
SizeConst=15)]
public CHAR filler[9];
}

I made my call as

status_rec[] status_array = new status_rec[64];
GetState(
timeout,
client_id,
ref status_array[0]
);

What I am getting in Status_array is the correct data in the first element,
and all zeroes thereafter.

Can anybody please point me to my mistake?

I think this may be useful

http://www.codeproject.com/csharp/groupandmembers.asp

There is a difference in that the example code allocates the space for
the buffer in the p/invoked dll, but the use of sizeof and Marshal
class may help.

This is also has a good explanation.

http://msdn2.microsoft.com/en-us/library/z6cfh6e6(VS.80).aspx#cpcondefaultmarshalingforarraysanchor3


KeithR wrote:
> I am something of a newbie in the world of C# data structures, but I am
> writing an application that needs to call a legacy DLL using .net 1.1. That
> is no big deal mostly, but I am having trouble with one function. It is
> defined in the original C as
>
> UINT32 __stdcall GetState(
> UINT32 timeout,
> UINT32 client_id,
> void *status_array
> );
>
> status is defines as a pointer to 64 status records (structs) they are
> defined as
>
> typedef struct status_rec {
> UINT32 type;
> UINT32 state;
> UINT32 version;
> UINT32 flags;
> CHAR ip_address[15];
> CHAR filler[9];
> } status, *p_status
>
> I defined this in C# as
>
> [StructLayout=LayoutType.Sequential, Pack=1, CharSet = CharSet.Ansii]
> public struct status_rec {
> public UINT32 type;
> public UINT32 state;
> public UINT32 version;
> public UINT32 flags;
> [MarshalAs(UnmanagedType.ByValArray, ArraySubType = UnmanagedType.U1,
> SizeConst=15)]
> public CHAR ip_address[15];
> [MarshalAs(UnmanagedType.ByValArray, ArraySubType = UnmanagedType.U1,
> SizeConst=15)]
> public CHAR filler[9];
> }
>
> I made my call as
>
> status_rec[] status_array = new status_rec[64];
> GetState(
> timeout,
> client_id,
> ref status_array[0]
> );
>
> What I am getting in Status_array is the correct data in the first element,
> and all zeroes thereafter.
>
> Can anybody please point me to my mistake?

This one is good too

http://www.codeproject.com/csharp/cs...select=1180022


DeveloperX wrote:
> I think this may be useful
>
> http://www.codeproject.com/csharp/groupandmembers.asp
>
> There is a difference in that the example code allocates the space for
> the buffer in the p/invoked dll, but the use of sizeof and Marshal
> class may help.
>
> This is also has a good explanation.
>
> http://msdn2.microsoft.com/en-us/library/z6cfh6e6(VS.80).aspx#cpcondefaultmarshalingforarraysanchor3
>
>
> KeithR wrote:
> > I am something of a newbie in the world of C# data structures, but I am
> > writing an application that needs to call a legacy DLL using .net 1.1. That
> > is no big deal mostly, but I am having trouble with one function. It is
> > defined in the original C as
> >
> > UINT32 __stdcall GetState(
> > UINT32 timeout,
> > UINT32 client_id,
> > void *status_array
> > );
> >
> > status is defines as a pointer to 64 status records (structs) they are
> > defined as
> >
> > typedef struct status_rec {
> > UINT32 type;
> > UINT32 state;
> > UINT32 version;
> > UINT32 flags;
> > CHAR ip_address[15];
> > CHAR filler[9];
> > } status, *p_status
> >
> > I defined this in C# as
> >
> > [StructLayout=LayoutType.Sequential, Pack=1, CharSet = CharSet.Ansii]
> > public struct status_rec {
> > public UINT32 type;
> > public UINT32 state;
> > public UINT32 version;
> > public UINT32 flags;
> > [MarshalAs(UnmanagedType.ByValArray, ArraySubType = UnmanagedType.U1,
> > SizeConst=15)]
> > public CHAR ip_address[15];
> > [MarshalAs(UnmanagedType.ByValArray, ArraySubType = UnmanagedType.U1,
> > SizeConst=15)]
> > public CHAR filler[9];
> > }
> >
> > I made my call as
> >
> > status_rec[] status_array = new status_rec[64];
> > GetState(
> > timeout,
> > client_id,
> > ref status_array[0]
> > );
> >
> > What I am getting in Status_array is the correct data in the first element,
> > and all zeroes thereafter.
> >
> > Can anybody please point me to my mistake?

DeveloperX wrote:

> I think this may be useful
>
> http://www.codeproject.com/csharp/groupandmembers.asp
>
> There is a difference in that the example code allocates the space for
> the buffer in the p/invoked dll, but the use of sizeof and Marshal
> class may help.
>
> This is also has a good explanation.
>
> http://msdn2.microsoft.com/en-us/library/z6cfh6e
(VS.80).aspx#cpcondefaultmarshalingforarraysanchor3
>
>
Thank you for that I will check out the references.