function import

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Thomas Fisher - 08 Sep 2004 20:34 GMT

Hello,

This is a rephrasing of a previous question that I didn't get an answer to,
maybe putting it differently will help.

In Baf.dll there is a function prototype:

BOOL CDECL LaunchRunner (LPCSTR szUserDisplay, BOOL* pbEnabled);

How would this be defined in VB.Net or C# and how should I call it? I've
tried everything I can think of and am getting null reference errors. I
posted code in the previous post (on 8/6).

Thanks a lot for any help with this...

- Tom

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BMermuys - 09 Sep 2004 01:33 GMT

Hi,

> Hello,
>
[quoted text clipped - 5 lines]
>
> BOOL CDECL LaunchRunner (LPCSTR szUserDisplay, BOOL* pbEnabled);

<DllImport("...", CallingConvention:=CallingConvention.Cdecl,
CharSet:=CharSet.Ansi) > _
Public Function LaunchRunner( _
ByVal szUserDisplay As String, _
ByRef pbEnabled As Boolean) As Boolean
End Function

If it doesn't work then maybe your c sign isn't right, the function doesnt
work properly or BOOL is different then the one in wtypes.h

HTH,
greetings

> How would this be defined in VB.Net or C# and how should I call it? I've
> tried everything I can think of and am getting null reference errors. I
[quoted text clipped - 3 lines]
>
> - Tom

Reply to this Message

Thomas Fisher - 09 Sep 2004 05:57 GMT

> <DllImport("...", CallingConvention:=CallingConvention.Cdecl,

CharSet:=CharSet.Ansi) > _

> Public Function LaunchRunner( ByVal szUserDisplay As String, ByRef

pbEnabled As Boolean) As Boolean

> End Function

> If it doesn't work then maybe your c sign isn't right, the function doesnt
> work properly or BOOL is different then the one in wtypes.h

Thanks for the reply! Ok, I've tried this and it still didn't work.
- by "c sign" are you referring to the declaration? If so, I'm sure
it's right.
- the function does work properly, i know because there is a control
panel that calls this function
- how would i know what type of bool to use? what others are there to
try?

Thanks for the help...

Reply to this Message

BMermuys - 09 Sep 2004 12:36 GMT

Hi,

>> <DllImport("...", CallingConvention:=CallingConvention.Cdecl,
> CharSet:=CharSet.Ansi) > _
[quoted text clipped - 11 lines]
> - the function does work properly, i know because there is a control
> panel that calls this function

Do you have some code in any language that uses the function which works ?

> - how would i know what type of bool to use? what others are there to
> try?

Well, the sign or declaration does it come from a header file ? If so,
check the header file if it defines or typedefs BOOL or if it includes any
other header which does so.

Something must be wrong, because I have a function with the same sign which
works without any problems.

Why do you allocate 255 chars for the string, does the function wants a
fixed size string ? The function doesnt alter the string does it ?

HTH,
greetings

> Thanks for the help...

Reply to this Message

Thomas Fisher - 09 Sep 2004 16:17 GMT

> Well, the sign or declaration does it come from a header file ? If so,
> check the header file if it defines or typedefs BOOL or if it includes any
> other header which does so.

Here's the definition from the header file:
BOOL CDECL LaunchRunner( LPCSTR szUserDisplay , BOOL* pbEnabled );
typedef BOOL (CDECL* fLaunchRunner)( LPCSTR szUserDisplay , BOOL*
pbEnabled );

> Something must be wrong, because I have a function with the same sign which
> works without any problems.

How do you call it? With a System.String and System.Boolean? Do you pin
them first?

> Why do you allocate 255 chars for the string, does the function wants a
> fixed size string ? The function doesnt alter the string does it ?

Because of what I read in this thread:
http://www.error-bank.com/microsoft.public.dotnet.languages.vb.1/205640_Thread.aspx

Reply to this Message

Thomas Fisher - 09 Sep 2004 07:01 GMT

Ok,

Here's an update of the code I'm using, still not working.

C++ Prototype from Baf.dll:
BOOL CDECL LaunchRunner (LPCSTR szUserDisplay, BOOL* pbEnabled);

C# Wrapper:
[DllImport("Baf.dll", CallingConvention=CallingConvention.Cdecl,
CharSet=CharSet.Ansi)]
public static extern bool LaunchRunner ( string szUserDisplay,
[MarshalAs(UnmanagedType.Bool)] ref bool pbEnabled ); //note: I've also
tried marshaling it is VariantBool and U1

VB.Net Call to C# Wrapper:
Dim buffer As String = "AB"
buffer.PadRight(255, vbNullChar)
Dim handle As GCHandle = GCHandle.Alloc(buffer, GCHandleType.Pinned)
Dim sPtr As IntPtr = handle.AddrOfPinnedObject

Dim B As Boolean = True
Dim bPtr As IntPtr = Marshal.AllocCoTaskMem(Marshal.SizeOf(B.GetType))
Marshal.StructureToPtr(B, bPtr, False)

If Not LaunchRunner (buffer, B) Then
Throw New Exception("LaunchRunner failed")
End If

Marshal.FreeCoTaskMem(bPtr)
handle.Free()

The function is returning false (no error) so something's not right but I
think I'm getting closer. It would be great if someone who knows more than
me could take a look at this and tell me what's wrong.

Thanks!

Reply to this Message

Robert Jordan - 09 Sep 2004 11:08 GMT

Hi Thomas,

> Ok,
>
[quoted text clipped - 9 lines]
> [MarshalAs(UnmanagedType.Bool)] ref bool pbEnabled ); //note: I've also
> tried marshaling it is VariantBool and U1

You don't need to manually marshal the string:

[DllImport("Baf.dll", CallingConvention=CallingConvention.Cdecl,
CharSet=CharSet.Ansi)]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool LaunchRunner(
[MarshalAs(UnmanagedType.LPStr)] string szUserDisplay,
[MarshalAs(UnmanagedType.Bool)] ref bool pbEnabled
);

bye
Rob

Reply to this Message

Thomas Fisher - 09 Sep 2004 16:21 GMT

Thanks for the help.

> You don't need to manually marshal the string:
>
[quoted text clipped - 5 lines]
> [MarshalAs(UnmanagedType.Bool)] ref bool pbEnabled
> );

I've changed the wrapper to match this and have tried calling it in several
ways and none work. An example call:

LaunchRunner("AB", True)

Any more ideas?

Reply to this Message

Robert Jordan - 09 Sep 2004 18:32 GMT

Hi Thomas,

> Thanks for the help.
>
[quoted text clipped - 14 lines]
>
> Any more ideas?

There are 2 kinds of unmanaged bools:

1 byte C++/C
4 bytes (WINAPI)

You may try whether the 1 byte version applies using
[MarshalAs(UnmanagedType.I1)] for both bools.

bye
ROb

Reply to this Message

Thomas Fisher - 09 Sep 2004 22:29 GMT

> There are 2 kinds of unmanaged bools:
>
[quoted text clipped - 3 lines]
> You may try whether the 1 byte version applies using
> [MarshalAs(UnmanagedType.I1)] for both bools.

Here's the definition from the header file:
BOOL CDECL LaunchRunner( LPCSTR szUserDisplay , BOOL* pbEnabled );
typedef BOOL (CDECL* fLaunchRunner)( LPCSTR szUserDisplay , BOOL*
pbEnabled );

I've tried it with I1 for both and still no go. I've been trying every
permutation i can think of...any other ideas?

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