I am trying to get some data from a C Dll via a structure and I am getting incorrect values back. I tried a couple of examples I found but they do not work. Since I do not know the proper way. I do not know how to fix it. Can anyone give me any advice, hints, redirection or any assistance what-so-ever. I've been struggling with this for weeks.
View 3 RepliesI am having a problem marshaling data between managed and unmanaged code. So I need to inspect the data at the byte level. What I need to do is store a number, say 8 into a 4-byte integer then copy it to an array bytArray(4) and compare those bytes with other data. I also need to set up the same array and copy it to an integer variable.
View 2 RepliesI am trying to develop a dll in VisualStudio2005 in vb.net that will communicate with a spectrometer attached to the USB port of the computer.Now the dll exists in C++ and it works like a charm. It is unmanaged code.Now if I try to translate this code in VB.net (because our app is in VB and my boss wants it in VB for maintainability) I have problems.
First of all, I am trying to create a file to open that port. The code in C++ looks like below and it works. Needles to say I tried to call the C++ dll from our app and it works. If I call the vb dll it doesn't. It gives me "access denied" no matter what I tried. I am not sure if my CreateFile is wrong or it's .net. I read somewhere that I need a manifest file included in the dll? Has anyone experience something like this? Why would i get "ACCESS DENIED" all the time?
// close and clear current stuff
ClosePort();
swprintf( sDevice, L"\\?\usb#vid_0765&pid_%s#******#{%s}", Device, PRIVATE_IID_STR );
[code].....
I need to write a DLL in C that is used a plugin for an existing application.The DLL has to be compiled by the Visual Studio 2008 compiler with the following options.[code]It's then linked to applications library's.What it actually needs to do and what's causing me the issues is that within one of the methods it needs to pull data from a sql server 2008 r2. From what I've seen today you wouldn't be able to do this directly in C as SQL Server past 2005 is designed to communicate with CLR languages( C#, C++, VB.Net).It was suggested that I handle all the database communication with a VB.Net dll and then call said function from within the C dll. Most of what I've found on the topic of calling managed dll's from unmanaged code has talked about pinvoke or com wrappers and mainly from the perspective of c++.
View 2 Repliesdebug the managed / unmanaged boundry environment: VS2010 on Win7 64bit
View 1 RepliesI have a C++ dll that contains a callback. The callback has one parameter that is passed in and one parameter that is passed out. The parameter that is passed from C++ is a variant. So, we are going from a variant in C++ to an object in VB.NET. The function works. However, It seems that there is a memory leak on the VB.Net side. This must be a Marshaling issue. I have tried to use the MarshalAs Functions, but to no avail.
VB.NET
Declare
Function EnableWriteNotification
Lib
[code]....
I've got some functions I need to call that are in some DLL files that have been written in Delphi 5 in a VB.NET 2005 application. I'm able to use the DllImport function to access the functions just fine; however, I'm having an issue with the Delphi string data type and passing it to and from the .NET application.
[Code]...
It takes two string parameters and one double. I can call this function from VB.NET just fine, but it will error as soon as it tries to use one of the string variables (so in this case, when it passes them to another function) and I've found that the string values in Delphi are junk when they've been passed to .NET. I'm guessing that the string objects behave and/or are encoded differently between .NET & Delphi 5, and that I have to apply some sort of Marshaling to the function parameters in .NET, but I've tried all of the different types of marshaling and nothing has worked. Unfortunately, I haven't been able to find anything about this issue on the internet.
Does anyone know how I can call this Delphi function from .NET and have it pass the string values in a manner so that they won't be corrupted when stored in Delphi?
I'm having trouble using a COM based DLL in that one of the parameters is of type VARIANT.
The C++ definition of the structure is as follows:
typedef struct CSimData
{
DWORD dwSigId;
[Code].....
From debugging i've been able to determine that the COM server is getting no value in vValue. Is there some sort of Marshaling that needs to be done to be able to set that VARIANT up on my side so that it can use it?
I have a VB6 program which calls a COM method, passing 2 arrays as parameters and expecting 2 arrays to be populated in response.The code is this, where ItemIDs and ItemClientHandles are the input array parameters and MyItemServerHandles and Errors are populated by the COM object.
Dim ItemIDs(2) As String
Dim ItemClientHandles(2) As Long
Dim Errors() As Long ' Array for returned Item related errors
Dim MyItemServerHandles() As Long ' Server Handles for Items
[Code]...
I have to create an array of structure type in VB.net. but I am getting error while marshaling this error. I have to pass this array of structure type in to Dll function.
Code:
Structure declaration:
<StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Ansi)> _
Public Structure dx_entry
<MarshalAs(UnmanagedType.ByValTStr, SizeConst:=10)> _
Public dx As String
[Code] .....
I am getting the following error:
An unhandled exception of type 'System.ArgumentException' occurred in Audit_Demo_2307.exe
Additional information: Type dx_entry[] can not be marshaled as an unmanaged structure; no meaningful size or offset can be computed.
how to open a "data link properties" dialog using manged code
View 1 Repliesi need to pass commands through a C++ dll to vb.net and the other way around. is there some code that needs to be in the C++ dll to make it work? im not good at C++ at all,
View 5 RepliesWhat's the advantages of the above types of dll? Is there any other type?
View 1 RepliesI am writing classes in VB.Net (both managed). The main class "A" creates an instance of "B". Class "B" must call a method of Class "A". I need to know two things (syntax, etc...):
1. How does class "A" tell class "B" what method to call?
2. How does class "B" call the method?
The method must pass back an array of Shorts (in this particular example), either as a return value, or as a ByRef argument.I don't want to use an event if I don't have to. The execution is timing critical. (I assume event handling involves a lot of overhead by the operating system, but I may be wrong.)
im trying to make a simple wrapper for lua. The only problem so far is that lua only accepts a method in a specific format.Delegate Function LuaC Function(ByVal lua_state As IntPtr) As Integer..That is how lua wants the method to look like. So it only accepts a function that looks like this: [code]
View 2 RepliesI created a vb.net dll called "WSdll.dll".I compiled it, created a type library (tlb), and registered it globally(gacutil)..It includes a file called wsutils.vb, which includes a namespace called "wsutils".In the namespace, there's an interface (with attribute) called "IWSconnection", and a class called "WSconnection".The interface and class are public, as are all methods and properties.[code]...
View 2 RepliesI have absolutely no background on programming in C (or any other unmanaged languages for that matter) yet I would like to use the GetBestInterface function from the IP Helper API in my .NET application. I tried to understand how P/invoke calls can be used to make calls to native methods, but there are many things that just don't make sense to me (like how types in managed code map to unmanaged types).
Is there an alternative function somewhere hidden in the System.Net namespace that does roughly the same thing? Or could I write my own alternative using existing base classes combined with some magic? Because that's basically what it seems to me: magic. There is no real explanation for how the method accomplishes what it does as far as I can tell...
I just discovered the LocalEndPoint property on the System.Net.Sockets.Socket class which I think could be quite useful in this. To my understanding it will do the best-interface-picking on my behalf and I'll just need to get the NIC that corresponds to the local endpoint.
I am having a very strange memory leak that seems related to databinding. It is very hard to reproduce, so I won't post any code here to do so, but will just describe the problem.We have data entry forms which have controls which bind to custom business objects through a BindingSource object.
View 7 RepliesIs it possible to start another EXE in Managed Code? At this time, all I can do is use:
System.Diagnostics.Process.Start(exeName)
Is there another way to call another EXE within the same project?
Is there anyway to create an OS or Managed thread, so that it can never be interrupted. Thread/Process priorities are not enough.
View 2 RepliesI have an application written in .NET 4.0 that needs to load in memory a native DLL (written C). At the moment I am using a P/Invoke call to LoadLibrary passing the path where the DLL is located. This works, but due to the fact that this DLL comes from a DB, I would like to know if it is possible loading it through a stream, avoiding then the necessity to store the DLL somewhere in the filesystem.
View 2 RepliesI have an application which has been succesfully installed on a number of different client machines.
The problem I now have is that I have been asked to allow third party applications, possibly written in a non .net language set to plug into my application and execute some of the code. Just a handfull of properties and half a dozen methods.
Now I can wrap up these properties/methods, make them public and have them in their own project which will be part of my solution but I have no idea where to go from here.
How do I make this portion of my application accessible to a third party application written in unmanaged code ?
Question: I use an embedded Firebird database in ASP.NET.
Now, Firebird has a .NET wrapper around native dlls.
The problem is, with the ASP.NET compilation and execution process, the dlls get shadow copied to a temporary folder. Unfortunately, only the .NET dlls, and not the native dll.
See [URL] for details.
Now, this makes it necessary to put the unmanaged dll somewhere into the system32 directory (or any other directory in the path environment variable).
Now, I want to change the wrapper/native dll (opensource), so it loads the dlls also if they are only in the bin folder.
Now, my problem is, how can I, in .NET, load an unmanaged dll from an absolute path ? The absolute path is determined at runtime, not at compile-time...
I have an unmanaged DLL and need to call one of its functions. Here's the [code]...
View 5 RepliesMaybe this is not true ... But how to connect an unmanaged DirectX to VB.NET? For anyone dll I use <DllImport()>, but Unmaged DirectX have interface.... Than I tried use "<ComImport(), Guid(...)...>", but I do not know how to use COM interfaces Maybe I did not really understand COM technolgy... I tried find documentation "how to use com interfaces", but found nothing.
View 1 RepliesI'm having some trouble finding the syntax for making function calls to unmanaged DLLs in VB.NET. Let's just assume there's a function "Connected" in unmanaged DLL "Connector.DLL". I want to call this function by creating an abstract function call to it.
I've seen some code out there that looks something like
[DllImport("Connector.DLL")]
Public Shared Function Connect(ByVal intPort)
But that syntax doesn't work for me.
I need to call a function in an unmanaged .dll written in C lang from vb.net. The function declaration looks like this [code]Now the behavior of this function is that it copies some data in argument "reply" and returns a numeric value which signals its pass/fail status. How do i pass it a string object so that it can copy data. Following is how i access this function.[code]When the call completes, returned status is absolutely fine but there is nothing in string "str". What is it that i am missing. I'm not sure about the string object that i am passing as argument.
View 3 RepliesI need to call a function in an unmanaged .dll written in C lang from vb.net. The function declaration looks like thisLONG _stdcall ReadInfo(char *reply);Now the behavior of this function is that it copies some data in argument "reply" and returns a numeric value which signals its pass/fail status. How do i pass it a string object so that it can copy data.Following is how i access this function.
View 2 RepliesI'm migrating some VB6 code to VB.net,the code contains a structure that contains 1d arrays, 2d arrays, and few other variables.The general outline of the Vb.net structure is as under
[code]...
The call to the dll is declared as under Public Declare Sub getState Lib "val.dll" (ByRef state As Test)Elsewhere on this site I realized that we have to "marshal" the structure to allow it to be compatible with the unmanaged code that is about to accept it.However I still receiving runtime errors when running the code, I don't have any clue of how to use the System.Runtime.InteropServices.Marshal class.What would be the correct way to pass this structure to the dll?EDIT: The original VB6 data type is
[code]...
I have event Button that creates text box in run time.
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim textbox1 As New TextBox
static Dim shiftDown As Integer
static Dim counter As Integer
[code]....
All the text boxes that has been created displayed in GroupBox control dynamically. how GroupBox control size can be managed according to quantity controls inside it.