Hi,
I try to write a DLL in D which could be called from C#. For testing I want
to write a Concatenate method. The call to the DLL method does not raise
any exception in C# but the out string strResult is empty or it contains
invalid characters.

I tested it with strcopy, toStringz, string.ptr and toUTFz or just passing
a pointer.
Could you give some advice?

D Dll
module mydll;
import std.c.stdio;
import std.c.windows.windows;
import std.c.string;

export extern(C) bool concatenate(
	LPCTSTR str1, LPCTSTR str2, LPTSTR strResult)
{
   strcpy(strResult, "Test");
   return false;
}

C#
namespace DllClient
{
    class Program
    {
        [DllImport("mydll.dll",
            CallingConvention = CallingConvention.Cdecl,
            SetLastError = false, CharSet = CharSet.Auto)]
            private static extern bool concatenate(
                string str1, // in
                string str2, // in
                StringBuilder strResult); // out

        static void Main(string[] args)
        {
            StringBuilder sBuffer = new StringBuilder(4);
            concatenate("abc", "def", sBuffer);
            System.Console.WriteLine("Concatenate Result: " +
sBuffer.ToString());
            System.Console.ReadLine();
        }
    }
}

Kind regards
André

>         [DllImport("mydll.dll",
>             CallingConvention = CallingConvention.Cdecl,
>             SetLastError = false, CharSet = CharSet.Auto)]
>             private static extern bool concatenate(
>                 string str1, // in
>                 string str2, // in
>                 StringBuilder strResult); // out

Question is if that StringBuilder really is equal to a char* in this case.

On Wed, 12 Oct 2011 17:10:09 +0100, Trass3r <un@known.com> wrote:

>>         [DllImport("mydll.dll",
>>             CallingConvention = CallingConvention.Cdecl,
>>             SetLastError = false, CharSet = CharSet.Auto)]
>>             private static extern bool concatenate(
>>                 string str1, // in
>>                 string str2, // in
>>                 StringBuilder strResult); // out
>
> Question is if that StringBuilder really is equal to a char* in this case.

I believe it can/does work with C DLLs, for example:
http://www.pinvoke.net/default.aspx/kernel32/FormatMessage.html

The first C# FormatMessage signature shown there uses a StringBuilder on the C# side.

R

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On Wed, 12 Oct 2011 18:00:10 +0200, Andre <andre@s-e-a-p.de> wrote:

> Hi,
> I try to write a DLL in D which could be called from C#. For testing I want
> to write a Concatenate method. The call to the DLL method does not raise
> any exception in C# but the out string strResult is empty or it contains
> invalid characters.
>
> I tested it with strcopy, toStringz, string.ptr and toUTFz or just passing
> a pointer.
> Could you give some advice?
>
> D Dll
> module mydll;
> import std.c.stdio;
> import std.c.windows.windows;
> import std.c.string;
>
> export extern(C) bool concatenate(
> 	LPCTSTR str1, LPCTSTR str2, LPTSTR strResult)
> {
>    strcpy(strResult, "Test");
>    return false;
> }
>
> C#
> namespace DllClient
> {
>     class Program
>     {
>         [DllImport("mydll.dll",
>             CallingConvention = CallingConvention.Cdecl,
>             SetLastError = false, CharSet = CharSet.Auto)]
>             private static extern bool concatenate(
>                 string str1, // in
>                 string str2, // in
>                 StringBuilder strResult); // out
>
>         static void Main(string[] args)
>         {
>             StringBuilder sBuffer = new StringBuilder(4);
>             concatenate("abc", "def", sBuffer);
>             System.Console.WriteLine("Concatenate Result: " +
> sBuffer.ToString());
>             System.Console.ReadLine();
>         }
>     }
> }
>
> Kind regards
> André

-            SetLastError = false, CharSet = CharSet.Auto)]
+            SetLastError = false, CharSet = CharSet.Ansi)]

CharSet.Auto will choose UTF-16 unless you add use the Windows ANSI method convention (i.e. name your function "concatenateA"). In D, LPTSTR will use ANSI by default.

Am Wed, 12 Oct 2011 21:49:14 +0200 schrieb casual.james@yahoo.es:

> 
> -            SetLastError = false, CharSet = CharSet.Auto)] +            SetLastError = false, CharSet = CharSet.Ansi)]
> 
> CharSet.Auto will choose UTF-16 unless you add use the Windows ANSI method convention (i.e. name your function "concatenateA"). In D, LPTSTR will use ANSI by default.

Thanks a lot. That was the missing part.
Now it is working.

Kind regards
André