link dll functions at runtime - dll

My program requires some function in a dll at runtime. How do I tell where the dll is? I can copy the dll into the program directory or system 32. Is there other neat way of doing this? Thank you. Also I am working in C++.

Are you using native code (C/C++/Delphi) or .NET? You should see my answer to Call Function from Dynamic Library for an example of how to do this with a native (not .NET) DLL.

Related

I made a project in C++ CLI, But I can decompile it using a C# Decompiler

Is there any way, I can prevent my c++ cli project from being decompiled if someone uses a C# decompiler, because I tried to decompile the .exe i made in ILSpy and it showed my whole code, so is there any way I can prevent this?
Thanks
as ancient as this thread is, I ran across it with the same question, and a newish answer. Can't specify the minimum version for this one, but
[module:System::Runtime::CompilerServices::SuppressIldasmAttribute];
on top of each .cpp module did the trick for me:
I didn't investigate much further, yet.
Another useful thing is to add
#pragma unmanaged
to each .cpp that does not contain .net code.
You can
Use a .NET obfuscator.
Or
Only use C++CLI for the boundaries of your app which require to Interact with .NET. And implement your logic in a native C++ library.

Create VB6 application using a class in a DLL, then swap out that DLL after build?

so my question is relatively simple, can I create VB6 application that references a class in a dll, and then substitute that dll for another at runtime?
Now my intial guess is... no chance in VB6.
So my thoughts turned to a VB.net interop dll. Could I do it in here, and then call the interop dll from the VB?
Again, my guess would be no.... but I'd be happy if someone knew differently.
The only thing that I think would actually work would be DI in .Net, but I'm limited to .net 2, or 3.5 at a big push, so I dont know if that is possible.
So for the background....
I have a dll that a specific site uses, but we dont want to ship that out to everyone. Instead, we want to build a clone dll which just has the interfaces setup so that the VB6 build will complete.
When it gets to the site that needs it, they want to replace the dummy dll, and drop in their version instead.
Note: We do use RegFreeCOM when its gets installed, so I do have the manifest files that I could play around with if needed.
Any ideas would be much appreciated.
Nick
Its a COM dll so its not statically linked to the VB6 exe, so long as the clsids and interface ids are the same in the type library for both DLLs, you can swap them around as you see fit. (If its a VB6 dll this is trivial to do with the 'binary compatibility' build option)
You could also use late binding instead and instead of making a reference directly in your VB6 code, you would create an object and then set that object to an instance.
Examples and information:
MVPS
Microsoft

What are Native DLLs?

When I was reading about DLLs on StackOverflow I came accross the word "Native DLLs" a lot of times. I found questions regarding them but I couldn't understand what a "Native DLL" actually is.
What is a native DLL?
Native DLL's are usually DLL's containing raw processor directly-executable code (such as that found in the Win32 API's) as opposed to, for example, managed (MSIL) which contain code that is consumed and JIT compiled to native processor instructions by a runtime such as the .NET CLR.
In .NET it is also possible to create mixed-mode DLL's that contain both native binary code and managed code.
this term came out when managed code that comes from .net assemblies was invented, to distinguish between managed and unmanaged =native code.
every .net assembly gets "nativied" by the JIT-compiler during execution. this means it gets translated to asm code that is "natively" understandable to the CPU.
The term native DLL was originally used before managed code existed. It was originally intended to refer to DLLs that are not COM DLLs. It is intended to refer to DLLs like the ones in Windows originally.
Note that Kev said "In .NET it is also possible to create mixed-mode DLL's that contain both native binary code and managed code." but that is not relevant; such a DLL is not a native DLL because it has CLI (.Net) metadata. Also, mixed-mode DLL's can only be developed using C++/CLI; no other language supports it.
See my article Native Windows Dynamic Link Libraries (DLLs) for more.
From what I understand a "Native DLL" will be a basic Win32 dll for example. A DLL that contains non managed code.
With .NET you write Managed assemblies. These will call the base level Windows code which is the same that a non-managed application will call.
A quick look through these MSDN search results will answer your question:
http://social.msdn.microsoft.com/Search/en-US?query=define:%20native%20dll&ac=8
It's simple a DLL that contains machine code, rather than MSIL.

How do I link to a DLL from javascript in XULRunner?

I have a dll (that I didn't write) and I would like to use it in an XULRunner application. I know nearly nothing about this, so bear with me. Apparently I can use XPCOM to load the dll and then call functions in it. How would I do that?
Or you could wait until xulrunner includes js-ctypes and call the DLL directly.

How to link a dll to Simulink?

I need to use a dll file in my Simulink model. Does anyone have any suggestions?
You can write a C S-Function, and call into your dll from the methods in the S-Function, or you can use the Legacy Code Tool, which is probably easier than writing your own.