C++ to C# help (thanks)

  • Thread starter Thread starter llihp
  • Start date Start date
L

llihp

Hi all, I'm new to C#, so apologies if this is a dumb question. smile

I'm trying to convert some code from C++ to C# so I can write some DLL
files.

Here is the original code in C++, firstly here is the header file:


Code:

// the interface structure
struct frontEndInterface {
short (* getParamCount) ();
short (* getReturnCount) ();
void ( * popInteger) (long & , short & );
void ( * pushInteger) (const long , short );
void ( * popString) (char *, short &, short &);
void ( * pushString) (const char *,short , short );
void ( * getFrontEndEnv)(const char *, char *, short &);
};

// a small macro used to declare the "exportable" functions
#define EXPORT __declspec(dllexport)

// the functions we want to be available from the front end
EXPORT void __stdcall initialize();
EXPORT void __stdcall finalize();

EXPORT int __stdcall myFunc(const struct frontEndInterface &fx);


Here is the .cpp file:

Code:

#include <stdio.h>
#include <sys/stat.h>


void __stdcall initialize() {

}

//
------------------------------------------------------------------------
--
/* the entry of the DLL. This function is the main function of a DLL and
is called when the DLL is loaded by the system. This is specific to
Windows systems */
BOOL APIENTRY DllMain( HANDLE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved
) {
return TRUE;
}


int __stdcall myFunc(const struct frontEndInterface &fx) {
return 1;
}


void __stdcall finalize() {

}


I've cut out all the extra code and just left the bare bones.

Here's my C# attempt:

Code:

using System;
using System.Runtime.InteropServices;
using System.Windows.Forms;

unsafe public struct frontEndInterface {
unsafe public extern short *getParamCount();
unsafe public extern short *getReturnCount();
unsafe public extern void *popInteger(ref long a, ref short b);
unsafe public extern void *pushInteger(long a, short b);
unsafe public extern void *popString(char *a, ref short b, ref short
c);
unsafe public extern void *pushString(char *a, short b, short c);
unsafe public extern void *getFrontEndEnv(char *a, char *b, ref
short c);
unsafe public extern void *popWString(char *a, ref short b, ref
short c);
unsafe public extern void *pushWString(char *a, short b, short c);
};

[Guid("E9B5EFB6-7AF4-41D1-AAC7-9AD909E8D6E1"), InterfaceType
(ComInterfaceType.InterfaceIsIDispatch)]
public interface _SimpleDll {
[DispId(1)] void initialize();
[DispId(2)] void finalize();
[DispId(3)] int myFunc(ref frontEndInterface fx);
}

[Guid("99DA9C29-2F53-4BAD-B621-5109060D6FE8"), ClassInterface
(ClassInterfaceType.None), ProgId("ConvertToPDF")]
class SimpleDll : _SimpleDll
{
public void initialize() {
}

public void finalize() {
}

public int myFunc(ref frontEndInterface fx){
return 1;
}
}


The C# code compiles ok, but my program cannot seem to use the dll.

Any help appreciated!
 
llhip,

Interfaces are used only through COM interop (at least in the scope of
using interfaces as a bridge between managed and unmanaged code).

What you have to do in this case is use a DllImport attribute in order
to call the functions that you are exposing from a DLL.

If these are not functions you are exposing, and it is an actual
interface on a C++ object, then you will have to use managed extensions for
C++ to access it, or expose the object through COM and expose it through COM
interop.

Hope this helps.


--
- Nicholas Paldino [.NET/C# MVP]
- (e-mail address removed)

llihp said:
Hi all, I'm new to C#, so apologies if this is a dumb question. smile

I'm trying to convert some code from C++ to C# so I can write some DLL
files.

Here is the original code in C++, firstly here is the header file:


Code:

// the interface structure
struct frontEndInterface {
short (* getParamCount) ();
short (* getReturnCount) ();
void ( * popInteger) (long & , short & );
void ( * pushInteger) (const long , short );
void ( * popString) (char *, short &, short &);
void ( * pushString) (const char *,short , short );
void ( * getFrontEndEnv)(const char *, char *, short &);
};

// a small macro used to declare the "exportable" functions
#define EXPORT __declspec(dllexport)

// the functions we want to be available from the front end
EXPORT void __stdcall initialize();
EXPORT void __stdcall finalize();

EXPORT int __stdcall myFunc(const struct frontEndInterface &fx);


Here is the .cpp file:

Code:

#include <stdio.h>
#include <sys/stat.h>


void __stdcall initialize() {

}

//
------------------------------------------------------------------------
--
/* the entry of the DLL. This function is the main function of a DLL and
is called when the DLL is loaded by the system. This is specific to
Windows systems */
BOOL APIENTRY DllMain( HANDLE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved
) {
return TRUE;
}


int __stdcall myFunc(const struct frontEndInterface &fx) {
return 1;
}


void __stdcall finalize() {

}


I've cut out all the extra code and just left the bare bones.

Here's my C# attempt:

Code:

using System;
using System.Runtime.InteropServices;
using System.Windows.Forms;

unsafe public struct frontEndInterface {
unsafe public extern short *getParamCount();
unsafe public extern short *getReturnCount();
unsafe public extern void *popInteger(ref long a, ref short b);
unsafe public extern void *pushInteger(long a, short b);
unsafe public extern void *popString(char *a, ref short b, ref short
c);
unsafe public extern void *pushString(char *a, short b, short c);
unsafe public extern void *getFrontEndEnv(char *a, char *b, ref
short c);
unsafe public extern void *popWString(char *a, ref short b, ref
short c);
unsafe public extern void *pushWString(char *a, short b, short c);
};

[Guid("E9B5EFB6-7AF4-41D1-AAC7-9AD909E8D6E1"), InterfaceType
(ComInterfaceType.InterfaceIsIDispatch)]
public interface _SimpleDll {
[DispId(1)] void initialize();
[DispId(2)] void finalize();
[DispId(3)] int myFunc(ref frontEndInterface fx);
}

[Guid("99DA9C29-2F53-4BAD-B621-5109060D6FE8"), ClassInterface
(ClassInterfaceType.None), ProgId("ConvertToPDF")]
class SimpleDll : _SimpleDll
{
public void initialize() {
}

public void finalize() {
}

public int myFunc(ref frontEndInterface fx){
return 1;
}
}


The C# code compiles ok, but my program cannot seem to use the dll.

Any help appreciated!
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