Question

I have yet to find a good reference on this topic. For this example we will take some C++ code that I’m trying to port over to C#.

In C++ land we have the following prototype for an external library function:

extern 'C' DWORD EXPORT FILES_GetMemoryMapping(   PSTR pPathFile,   PWORD Size,   PSTR MapName,   PWORD PacketSize,   PMAPPING pMapping,   PBYTE PagesPerSector); 

and in it is used like such:

FILES_GetMemoryMapping((LPSTR)(LPCTSTR)MapFile, &Size, (LPSTR)MapName, &PacketSize, pMapping, &PagePerSector); 

Now I’m trying to port the first line over to C# and here is where I’m presented with no clear path.

This is what I’ve got so far:

[DllImport('Files.DLL')] public static extern uint FILES_GetMemoryMapping(     [MarshalAs(UnmanagedType.LPStr)]     string pPathFile,     out ushort Size,     [MarshalAs(UnmanagedType.LPStr)]     string MapName,     out ushort PacketSize,     IntPtr pMapping,     out byte PagesPerSector); 

Now the question is: Is there any good guide out there that tells me a ‘PSTR pPathFile’ should be ‘[MarshalAs(UnmanagedType.LPStr)] string pPathFile’ … Assuming that is correct?

Or, a that a pointer to a ‘PMAPPING’ struct becomes a ‘out IntPtr pMapping’ … assuming that is correct?

Any help on this one guys?

Answer 1

I have yet to find a good reference on this topic

Here you go.

Oddly, the site is down at the moment, but it’s a very good resource for marshalling problems. In the mean time, you can use Archive.net’s archive of pinvoke.net at http://web.archive.org/web/20080202041852/http://www.pinvoke.net