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C# Cannot Return Variants

Post your question and get tips & solutions from a community of 418,747 IT Pros & Developers. FciAPI.FCICreate( erf, new PFNFCIFILEPLACED( file_placed ), new PFNFCIALLOC( mem_alloc ), new PFNFCIFREE( mem_free ), new PFNFCIOPEN( fci_open ), new PFNFCIREAD( fci_read ), new PFNFCIWRITE( fci_write ), new PFNFCICLOSE( fci_close ), new Why are Squibs not notified by the Ministry of Magic Does トイレ refer to the British "toilet" or the American "toilet"? By marshaling, we would be losing the size of the allocated buffer that is stored at ptr-4.

By using ExactSpelling turned off, you tell the compiler to search this variances, allowing you to import Win32 API easily. Remainder of method body removed ... Read it from the stack   SearchClient = CType(Marshal.PtrToStructure(newptr, GetType(Dhcp.DHCP_CLIENT_INFO)), Dhcp.DHCP_CLIENT_INFO)     ' Subnet mask for the computer    iSubnetmask = SearchClient.SubnetMask     ' Read the mac address from the stack    Dim BufferAddress char* MyAppend(char* in, char* arg1, char *arg2, char*arg3, BOOL last); void KillBuffer(char* in); MyAppend gets 5 parameters: first is a char* buffer that holds the concatenated string so far and http://stackoverflow.com/questions/17137333/c-sharp-application-calling-c-method-error-pinvoke-cannot-return-variants

Draw some mountain peaks Is "she don't" sometimes considered correct form? doesn't help. This is a lot of work, and IMHO a much better option would be to create a wrapper in Managed C++.

I would say, this is a wise decision. Inside your C++ function, the parameter would be a pointer to a VARIANT that you can fill in (the variant exists already, but you fill it in with data). This article's name is a bit too broad. And I do agree that it would be nice to have an RCW debugger.

I've listed a few lines of code below. Oh, and you'd need to convert the VB prototype to a Sub and not a Function. How to pass the instance of that class as pv paramter? You can also try to serialize your C++ object into a byte array and then just return a buffer / length to C# that will first deserialize the object into a

CallingConvention tells the compiler which is the calling convention for our DLL. What is the definition of "rare language"? Please Help Me.. see msdn: "Default Marshaling for strings" Imports System.Text Imports System.Runtime.InteropServices Public Class Form1 _ Private Shared Function GetWindowTextLength(hWnd As IntPtr) As Integer End Function _ Private Shared Function GetWindowText(hwnd

The Dll being called resides in the project directory. Wait... Regards, Gert Sign In·ViewThread·Permalink thanks, this helped a lot scottelloco9-Mar-06 9:51 scottelloco9-Mar-06 9:51 Thanks for the article Marius. Not the answer you're looking for?

Visit our UserVoice Page to submit and vote on ideas! Regards, Marius CONSTANTIN Sign In·ViewThread·Permalink Last Visit: 31-Dec-99 18:00 Last Update: 5-Nov-16 15:18Refresh1 General News Suggestion Question Bug Answer Joke Praise JaimeVSDC17-Aug-06 5:42 JaimeVSDC17-Aug-06 5:42 Does this article still apply for Visual Studio 2005 ? Background When the .NET and managed code appeared, it was clear that is required the interoperability between the legacy code written in some language (like C++ or Delphi, you name it)

Anonymous Answer Email {} Share You do not declare the library itself in VB, you only declare individual functions from the library. Privacy statement Help us improve MSDN. So, .NET creators probably used the same principle I suggest: avoiding dealing with variant types. PtrToStructure is not working.

needs Cdecl calling convention - you have to modify the IL !!! ) public delegate IntPtr YourMemAlloc(int cb); public void mem_free( IntPtr memory ) { } This is a lot of Add-in salt to injury? But, if you don't marshal explicitly all parameters that involve pointers, unsafe keyword it's required.

The DHCP_SEARCH_INFO structure must be: Public Structure DHCP_SEARCH_INFODim SearchType As Integer ' 0=IpAddress, 1 = HW-Address, 2=Clientname Dim SearchInfoEnd Structure Puuh....

If you define most of your classes in C++/CLI, you can just pass the relevant (managed) instances to your C# application without additional conversion. (You will, of course, still have to Sign In·ViewThread·Permalink Marshalling: Using native DLLs in .NET meukjeboer25-Sep-08 2:30 meukjeboer25-Sep-08 2:30 Please read the article: "Marshalling: Using native DLLs in .NET" http://blog.rednael.com/2008/08/29/MarshallingUsingNativeDLLsInNET.aspx It's an in-depth article about how to Note that long in C++ is 4 bytes, and Long in C# is 8 bytes. If we declared as string, the .NET framework would marshal the string for us because the only type of strings that exist in the .NET world are Unicode.

You may also be interested in... Is it unethical to poorly translate an exam from Dutch to English and then present it to the English speaking students? So, IMHO, you should change your article title to a less generic one, so at least people understand : - what you are talking about : I had to read the see msdn: "Default Marshaling for strings" Imports System.Text Imports System.Runtime.InteropServices Public Class Form1 _ Private Shared Function GetWindowTextLength(hWnd As IntPtr) As Integer End Function _ Private Shared Function GetWindowText(hwnd

First of all we need tell the compiler that we will be dealing with legacy application and pointers (only if required). But i am not able to import class from MFC dll into my C# code. Worked perfectly :D I just had to add " Imports System.Runtime.InteropServices " for it to work. –Snipex Mar 25 '14 at 20:34 add a comment| Your Answer draft saved draft Similarly, std::string makes no sense to .NET, since it's a C++ type, relying on unmanaged memory allocation and with a different internal string format and different semantics than C#.

Advisor professor asks for my dissertation research source-code Why put a warning sticker over the warning on this product? To emailaddress: To name: From name: Extra information in the email body (optional): Email: I am sending you the codedump of Calling a DLL from Visual Studio VB 2015 that you You can't change a .Net string. The whole code I try: [ DllImport( "cabinet.dll", CallingConvention = CallingConvention.Cdecl ) ] public static extern IntPtr FCICreate( [ In, Out, MarshalAs( UnmanagedType.LPStruct ) ] ERF perf, PFNFCIFILEPLACED pfnfcifp, PFNFCIALLOC pfna,

Passing void* instance. Page 1 of 1 New Topic/Question Reply 3 Replies - 10345 Views - Last Post: 25 June 2008 - 07:43 AM Rate Topic: #1 rpradeepa New D.I.C Head Reputation: 0 Errors on parameter passing Would C++/CLI solve PInvoke problems that C# has in this situation? Nov 16 '05 #2 P: n/a promko Thank you for your reply.

Had also to change the "ByVal SearchInfo" to a "ByRef SearchInfo" to avoid unbalancing the stack. Another thing to mention is that you need to reference the InteropServices namespace like this:using System.Runtime.InteropServices; Let's start importing the functions:class MyDLL { [DllImport("legacy", EntryPoint = "MyAppend", ExactSpelling = true, // Today's Topics Dream.In.Code > Programming Help > VB.NET PInvoke restriction: cannot return variants. Also, I must say that P/Invoke isn't the only way to reuse the existing DLL code.

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