I'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 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 ?
What will happen when 3 function calls same function at a time? I have 3 Function, f1,f2,f3.. Those function after completing their task will call finish() function. What will happen if Finish is Called morethan once..
View 9 RepliesI have an unmanaged DLL and need to call one of its functions. Here's the [code]...
View 5 RepliesI really need little help with unmanaged dll access from VB.NET, have been working on it about a week. I have a C++ .h files with headers. I have to access one function from the dll using VB.NET:
int
acsGetEventPoll (int acsHandle,
void FAR*eventBuf,
unsigned short FAR*eventBufSize);
Documentation says that eventBuf is a buffer where structure of type CSTAEvent_t is put after the function call. Type is defined as:
[Code]...
I want to get a list of all students who were at one of two events. Here's my function to get an attendance list:
Private Function AttendanceList(ByVal Mode As AttendanceListLookupMode, ByVal AttendaceTypeID As Integer, ByVal EventID As Integer, ByVal EventOccurenceDate As Date) As IEnumerable(Of Integer)
'Get the attendance table for specified event[code].......
In VS2010 I'm encountering a PInvokeStackImbalance error when I call an unmanaged C function that takes a string argument. This only happens in VS2010 (works fine in earlier versions of vs). I know the MDA is more strict in VS2010 but I can't seem to figure out what the actual problem is.
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I am looking for a utility/tool to convert calls to legacy VB6 functions to the .NET equivalent. For example, it would convert this...
[Code]....
Does anybody know of one, or am I going to have to roll my own?
I tried to search forum topics to find a tutorial that will guide me on how to achieve this however seem like most of the tutorials i were finding were confusing me more.With that being said here is what i have,Here is what I am trying to do [URL]that tutorial is exactly what I am trying to achieve however I do not understand what the supplierstableadpater, northwindtableadapters are. I can only assume that I am not doing exactly the same thing as that tutorial.
What I have is a simple sql storedprocedure that selects all employeedetails.And also another sql stored procedure that selects just a few columns from the employees table. On my frist page I am going to list all the employee names in a gridview and when they click the employee name it should take them to another page and show that employee's details. Seems like you have to use an object datasource to achieve this but is there an easier way to achieve creating a class that calls the 2 stored procedures that I have that i would be able to then link them with an objectdatsource?
In vb.net, it is possible to design a function which can operate on generic parameters which meet multiple constraints. For example, it is possible to have a function accept as a parameter a class which inherits from Control and implements IList. This function could use "Control" or "IList" methods on such an object, and also pass the object to anything that expected a Control or an IList [note that this particular combination was chosen to facilitate a brief example, not to be a particularly useful combination].
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This approach provides compile-time type-safety; there's no need for a cast that could fail at runtime. An alternative approach would be to pass the argument as either a Control or an IList, and have the function cast to the other. That would, however, fail at runtime if the object that was passed didn't in fact meet both constraints.
Under what circumstances is it good to use a generic function like the above, in what cases would it be better to have objects which are going to meet both constraints have a new interface like IListableControl(Of T) which would include a TheControl property that would return itself (cast as a control), and in what cases would it be better to have a generic ISelf(of T) interface, any implementor of which would be expected to provide a "Self" property that would return itself as a T?
Using multi-constrained generics, it's possible to do a lot of things without requiring any run-time typecasts, but I don't know what the performance costs are likely to be. I tried writing a short program to generate 65,536 different generic types at run-time, e.g. Foo(of Bar(Of Foo(Of Foo(Of Bar(Of Foo(...(Of Blah)) and it got pretty slow, so I can tell that the time required to handle generics isn't fixed, but I don't know what factors affect it.
how to pass system.type or a generic without much luck. I have two functions below one that works and the other that doesn't. I can't seem to make heads or tails of the VB syntax required for doing what I want to do.
' This function does not
'
' Also attempted it like this
' Public Shared Function UnserializeFromJSON(ByVal obj As String, ByRef ty As System.type)[code].......
I have a camera for which the complete source code with header files(.h) and all libraries files(.lib) are given in VC++. Now if I want to access the function calls in the header files and in turn the functions in the library from VB.NET, I am required to write a wrapper DLL for accessing the function calls which I never did till now.
View 1 RepliesWhat the Win32 API is? I have looked around but no where really outlines what it is. Is it basically a set of procedures, outlined by Microsoft for programmers in order to get services from the operating system? In essence is it the equivalent to making system calls abd and library calls in UNIX? And yes I now Windows makes library calls too.
View 2 RepliesI have been using DBTransaction for my current projects that access a single database. However, I read some documentation on TransactionScope and was wondering in which scenario would using TransactionScope be better? Or should I be replacing DbTransaction calls with calls to TransactionScope?
View 2 RepliesI'm using Telerik RadControls, in my codebehind I have the following function, a portion of which adds buttons to the footer.
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i 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 Repliesim 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 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 RepliesQuestion: 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...
Maybe 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 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
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What should be the VB signature for the unmanaged function void PopulateBSTR(BSTR outstring)?The function PopulateBSTR does a SysAllocString and populates the string. Note the unmanagaed signature has the argument BSTR and not BSTR*. I can marshal the BSTR string using IntPtr signature when the C++ signature has BSTR* as the argument.
(The unmanaged code is an external dll which I cannot modify but I need to use.)
I've read about this issue on MSDN and on CLR via c#.Imagine we have a 2Mb unmanaged HBITMAP allocated and a 8 bytes managed bitmap pointing to it. What's the point of telling the GC about it with AddMemoryPressure if it is never going to be able to make anything about the object, as it is allocated as unmanaged resource, thus, not susceptible to garbage collections?
View 3 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 RepliesI am using a function from a dll in unmanaged code that requires a callback to my managed code in Visual Basic 2010. The callback is asynchronous and is called continuously over the life of the application. What's the best way to protect the callback function from the garbage collector? Right now it is being collected after several dozen calls from the dll.
View 11 RepliesI 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 Replies