In the past we experienced some problems using a DLL library created with Visual Studio 2005 in our Visual Studio 6.0 application (VS2005 DLL was C++ unmanaged, of course). In your opinion can we fall in the same kind of problem if the library is static (*.lib) and not dynamic?
It seems like the problem area would be the runtime libraries -- if the VS2005 DLL is using the DLL versions of the runtime libraries, then you would need both sets of runtimes installed when the application is installed. If your VS2005 DLL is statically linked to the VS2005 runtime, then it should be OK.
Microsoft recommends that unmanaged DLLs must be compiled with the same CRT / STL as the main application. And the main application and the DLL should be using dynamic linking with the CRT.
If the DLL implements a pure C-interface or a COM-interface, then it should be possible use DLLs from another version of Visual Studio. But if the DLL doesn't use static linking of the CRT, then it will require that the CRT-dlls are available.
It depends on what kind of problems of course. There are some conflicts that are more likely to occur in DLLs and some that are more likely to occur in static libs. If you are building against the same version of the Microsoft SDK it will minimize the problems.
Related
I'm writing a simple C++ application in Visual Studio. It also has a setup project.
It works well on my development machine, but when I'm installing this application on user's machine it requires Visual C++ Redistributable Package. I'm wondering why does my application require C++ Redistributable? Standard C++ runtime library is shipped with Windows, isn't it?
The only version of the C runtime library which is shipped by Microsoft with most of 32 bit Windows versions is msvcrt.dll. This library provides a typical set of library functions required by C and C++ programs. These include string manipulation, memory allocation, C-style input/output calls, etc.
Visual Studio 6.0's compiler links against this library, so if you are developing in VS 6.0 you shouldn't encounter any problems on most users' machines.
However, if you are developing in VS 2005, VS 2008, VS 2010, VS 2012, VS 2013 or VS 2015, you have to distribute additional C runtime libraries along with your application. This is because their compilers link against msvcrt80.dll, msvcrt90.dll, msvcrt100.dll, msvcrt110.dll, msvcrt120.dll and msvcrt140.dll respectively, which are not shipped with Windows.
Solutions:
Possible solution is to link statically with runtime library, but it may cause a lot of problems in case you have both .exe and .dll in your application. Don't do that.
To be more specific, I'll allow myself to quote a part of this answer:
Using /MT is risky if you create DLLs as well as an EXE. You'll end up
with multiple copies of the CRT in your program. This was especially a
problem with earlier versions of VS where each CRT would get its own
heap, not so much with VS2012. But you can still have ugly runtime
problems when you have more than one "errno" variable for example.
Using /MD is highly recommended to avoid such lossage.
Another possible solution is to require an appropriate Microsoft Visual C++ Redistributable package to be installed on the user's machine.
It may be done by specifying this requirement in prerequisites property in your setup project.
Also, you can distribute the runtime dll by including in your setup project the appropriate "merge module". In this case don't forget to add the appropriate "policy merge module" to avoid errors caused by incorrect runtime version.
Finally, you can just put required DLLs in the same folder in which your application is installed.
Further reading:
"Redistributing Visual C++ Files" - Official MSDN documentation
Even though some comments said that «link statically with runtime library, but it may cause a lot of problems when you have both .exe and .dll in your application.» this is NOT TRUE. First we DON'T statically link DLLs! We statically link OBJs and LIBs. LIBs are static libraries; DLLs are dynamic libraries, and you may choose to use LIBs (static) or DLLs (dynamic). It's entirely up to you to choose. The ONLY drawback (for the DLL fans) is that if you want to update one library, you need to compile and link again. I personally deploy ALL my software static linked and because of that I earn the bonus of don't even need installers. The software I develop is 100% portable (a feature that in the pre-installer era was general procedure), and the final user is free to simple COPY from one folder to another or even from the hard drive to flash drive (or vice-versa). The error message «DLL not found.» simply doesn't exist ... NEVER.
Some folks think of statically linking as toy software: WRONG! I can write a full featured application that connects to a DBMS (Oracle, SQL Server, ...) or any other kind of application.
I know this has been asked in other places and answered, but I'm having issues with MS Visual Studio 2010. I've developed a C++ executable but if I run the Release version on a machine that doesn't have the VC++ runtime library (ie, msvcr100d.dll), I get the "program cannot start because msvcr100d.dll is missing from your computer" error.
This is weird for two reasons:
Why is it trying to link with the debug version of the redistributable?
I tried applying this fix, setting the runtime library setting to /MT instead of /MD (multi-threaded DLL), but that only made the problem worse (if I manually copied msvcr100d.dll, it then said it couldn't find msvcp110.dll).
How can I package the runtime library with my executable so that I can run it on machines that don't have MS VC 2010 or the redistributable installed?
I know it's considered a security risk to include a copy of the DLL since it won't ever be updated, but my goal is just to send this executable to a few friends in the short term.
You definitely should not need the debug version of the CRT if you're compiling in "release" mode. You can tell they're the debug versions of the DLLs because they end with a d.
More to the point, the debug version is not redistributable, so it's not as simple as "packaging" it with your executable, or zipping up those DLLs.
Check to be sure that you're compiling all components of your application in "release" mode, and that you're linking the correct version of the CRT and any other libraries you use (e.g., MFC, ATL, etc.).
You will, of course, require msvcr100.dll (note the absence of the d suffix) and some others if they are not already installed. Direct your friends to download the Visual C++ 2010 Redistributable (or x64), or include this with your application automatically by building an installer.
For me the problem appeared in this situation:
I installed VS2012 and did not need VS2010 anymore.
I wanted to get my computer clean and also removed the VS2010 runtime executables, thinking that no other program would use it.
Then I wanted to test my DLL by attaching it to a program (let's call it program X).
I got the same error message.
I thought that I did something wrong when compiling the DLL.
However, the real problem was that I attached the DLL to program X, and program X was compiled in VS2010 with debug info. That is why the error was thrown.
I recompiled program X in VS2012, and the error was gone.
This problem explained in MSDN Library and as I understand installing Microsoft's Redistributable Package can help.
But sometimes the following solution can be used (as developer's side solution):
In your Visual Studio, open Project properties -> Configuration properties -> C/C++ -> Code generation
and change option Runtime Library to /MT instead of /MD
Usually the application that misses the .dll indicates what version you need – if one does not work, simply download the Microsoft visual C++ 2010 x86 or x64
from this link:
For 32 bit OS:Here
For 64 bit OS:Here
I got the same error.
I was refering a VS2010 DLL in a VS2012 project.
Just recompiled the DLL on VS2012 and now everything is fine.
Debug version of the vc++ library dlls are NOT meant to be redistributed!
Debug versions of an application are not redistributable, and debug
versions of the Visual C++ library DLLs are not redistributable. You
may deploy debug versions of applications and Visual C++ DLLs only to
your other computers, for the sole purpose of debugging and testing
the applications on a computer that does not have Visual Studio
installed. For more information, see Redistributing Visual C++ Files.
I will provide the link as well : http://msdn.microsoft.com/en-us/library/aa985618.aspx
Where can I find some official note, kb article or other documentation describing changes to the Visual Studio 2010 C/C++ runtime linking and deployment policy?
Under Visual Studio 2008 (with the VC90 runtime) a manifest was embedded in native images, and the runtime libraries were deployed as side-by-side assemblies (WinSxS). This caused problems when rebuilding a native exe or library using VS 2008 SP1, in that an updated version of the C++ runtime was required by the embedded manifest.
For VS 2010 and the MSVCR100 runtime version, the policy seems to have changed completely.
The file msvcr100.dll and the other C/C++ runtime libraries are no longer install as SxS assemblies.
When compiling under VS2010, no runtime 'dependency' entry is added to the embedded manifest, meaning that any version of msvcr100.dll might be loaded at runtime.
On machines with .NET 4 installed, the matching runtime is named msvcr100_clr0400.dll, and won't be loaded by native code, though a copy renamed to msvcr100.dll works fine. I think this means any process with C/C++ code will always have two versions of the same C/C++ runtime loaded.
This seems to be a significant change in policy, backtracking from the SxS deployment and manifest dependencies we had under VS 2008. Could anyone shed more light on what changed, and perhaps point to some documentation, a readme or blog post that describes these changes, the motivation and related impact?
It think it's better this way - the strong version manifest and SxS deployment was a nightmare - but I'm surprised at these unexpected and seemingly undocumented changes in VS 2010.
Bonus question: How can I compile my C++/CLI library under VS 2010 to link to msvcr100_clr0400.dll instead of msvcr100.dll? This idea is that the C++/CLI assembly should run with no dependencies other than that installed by .NET 4 (without static linking).
You already answered most of your question, the side-by-side deployment of the CRT was a nightmare that got way too many programmers in trouble. Microsoft agreed and gave up on it for the VS2010 release. It's back to a DLL in c:\windows\system32, named msvcr100.dll. And msvcp100.dll, vcomp100.dll, atl100.dll, mfc100.dll, mfcm100.dll, the other runtime support DLLs. The way it was for VS2003 and earlier editions. Now it is again the user's burden to sort out a DLL Hell problem. The person least likely to be able to do so but they do tend to have a budget to pay for support. Unlike programmers that need to get help from a free web site :)
But you can help, app-local deployment is now again enabled, you can deploy msvcr100.dll in the same directory as your main EXE. That was explicitly checked and forbidden in previous versions. App-local has some niceties, it isolates you from well-meant but unfortunate updates that break your app. Albeit that you are now yourself responsible for getting updates deployed that fix a security hole. If that's uncomfortable then deploy and rely on the copy in the system directory.
Do not try to link to msvr100_clr0400.dll, that's a private copy for use by the CLR. Much like msvcr.dll is a private copy for use by Microsoft DLLs. You don't have the .lib file you need to link to these DLLs.
Just a couple of links about the topic – I hope someone will find them useful:
Visual Studio 2010 changes for VC++ (part 5)
Visual C++ Application: How to use manifests and re-distributable assemblies?
I have a C++ dll. Is there a way to compile it so that it can be used with VS2005/2008/2010 instead of me having to do 3 different builds?
Thanks
You can generally "use" a C++ dll with any version of Visual Studio, if you're just linking to it.
However, when your dll is compiled, it will be targetted to a specific version of the C++ runtime, so end-users of your program will need to have that runtime (Visual C++ redistributable package) installed on their PC. So if you use a dll built by VS2005 and an exe built by VS2010, your end user will have to install both the 2005 and 2010 redistributable packages. The same generally goes for other libraries if you use them (MFC, etc)
If you do this, you will also have to be careful about memory allocation - memory allocated in one runtime version cannot be safely deallocated by another. So anything that your dll allocates must also be deallocated by the dll, and anything allocated by your exe must not be deallocated by the dll.
As a result, most people will rebuild the dll with the same version of VS as they build the rest of their program in, to minimise the compatibility issues - ultimately it's much easier to build in each verison of VS than to sort out all the issues involved in not doing so.
(Hint: You can run VS from the command line and get it to build a project/solution, so it's a 5 minute job to write a batch script that will automate building all three variants in one go)
The version of visual studio in use doesn't make a difference as to whether a given assembly can be referenced.
The only thing that matters is what version of the framework the assembly was compiled against.. Assuming it's a .net assembly anyway.
Regardless, it's common practice to provide versions compiled against each framework rev (2.0, 3.5, and 4.0) anyway.
However, if you are compiling an unmanaged c++ dll; then just provide a 32 bit and a 64 bit version of that dll. In this case the .net version in use (and visual studio version for that matter) is immaterial.
I'm developing an SDK, and we have clients that are still coding with VC++ 6, while others use Visual Studio 2005 and others with 2008.
Currently, we build several flavors of our SDK, where we build the exact same source code with each of those compilers. I want to find out if that is really necessary. Is it safe to build our SDK (which takes the form of DLLs) with VS2008 and expect our clients who use VC++ 6 to be able to use it without problems?
Depends. Does your DLL depend on the VC runtime, MFC or ATL? If so, your clients will have to distribute those dlls. Does your dll export C++ structs/classes/functions? There is no standardized ABI for C++, so they may or may not work with other compilers. If your dll only exports extern "C" {} style, you'll be fine.
It is pretty safe if you'll not allow client's program to delete memory that was allocated in your SDK. And vice versa.
If the DLL has a pure C API, your executable will never release any resource allocated by the DLL (and vice versa), then it should work.