Marshalling from C++ DLL to CSharp for const wchar_t * using Visual Studio 2008 SP1

[KYAW KYAW OO]

Dear All,

I am stuck on these C++ data types const wchar_t * since last week.

It worked well in C# console application under mentioned below

 unsafe static void Main(string[] args)
{
  IntPtr ld, data1, data2;
  string str = "test.txt";
  int UTF_8 = 1;
 
  // Using PInvoke 
[System.Runtime.InteropServices.DllImportAttribute("Test.dll", EntryPoint = "LoadFromFile")]
public static extern System.IntPtr LoadFromFile(System.IntPtr aObj, System.IntPtr ex, [System.Runtime.InteropServices.InAttribute()] [System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.LPWStr)] string aPath, int aWritable);
 
[System.Runtime.InteropServices.DllImportAttribute("Test.dll", EntryPoint = "LoadFromFile_cset")]
public static extern System.IntPtr LoadFromFile_cset(System.IntPtr aObj, System.IntPtr ex, int aEncoding, [System.Runtime.InteropServices.InAttribute()] [System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.LPStr)] string aPath, int aWritable);
 
  // data1 and data2 should have some address
  // get some address in console application heredata1 = LoadFromFile(ld, IntPtr.Zero, str, 1);
data2 = LoadFromFile_cset(ld, IntPtr.Zero, UTF_8, str, 1);
 
  // but I got can't get any address in C# Window Form
 
}

Here is origina C++ functions

 struct Doc *API LoadFromFile (struct Loader *  aObj, struct Exception *  ex, const wchar_t *  aPath, int  aWritable) 
 
struct Doc *API LoadFromFile_cset (struct Loader * aObj, struct Exception *     ex, int     aEncoding, const char * aPath, int aWritable) 

So far I knew Marshalling or PInvoke used in anywhere console or window form, the result should be the same.

But very strange for this time since I am using other party libraries so I couldn't debug inside.

I hope some one will advise me since I need to close the case by tomorrow.


Thanks and best regards