I'm happy with dynamic linking while creating small c++ windows applications. But now I need to add a third part library. I have both a dll and a lib file. I prefer not to copy third party dll each time I install my application. Can I somehow link newly provided library statically while keeping whole project dynamically linked? In Microsoft Visual Studio IDE I found only one place where I can choose static/dynamic linking, in Properties->Configuration Properties->Code Generation->Runtime Library. But I suppose this selection is for the whole project and I need to link some libs statically and some of them dynamically.
UPDATE
In general I need to link some libs dynamically and others statically in the same project. The provided link tells only about static or dynamic linking in the same project
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I have some confusion about static and dynamic linked libraries and .lib and .dll files.
I have a project with two libraries, one I built myself and one is from an open source library.
The one I built myself is a separate project in the same solution (Visual Studio 2015, C++), and I don't need to copy over the .lib files or create a DLL for the executable to build and run
For the other open source library, I do need to copy over the .lib file and the DLL into the executable folder. However, I thought it would be possible to statically link a .lib file and not have to copy over the DLL.
Does this mean I need to compile the Open Source library differently? Like change the define __declspec(dllexport) to __declspec(dllimport) ? Or change /mD to /mT in compiler options?
I tried both of these, but it's still saying that it can't start without the .dll
Or can I get away with changing a setting in the executable project to link this library statically? If so, what are these settings?
EDIT: I know this is a standard question that can be looked up on google, but I haven't been able to find an exact answer for a while. Mainly, I'm confused about what settings need to be changed, and which project they need to be changed in. (The library or the executable).
I'm under assumption that static linking means the library is built into the executable, and dynamic linking means the library needs to be in a separate file, if this is incorrect, please let me know. Otherwise, I need to know how to build the library into the executable file.
And I can go ahead and change the build options in the open source library, and I tried this already.
Thanks,
-D
In Windows, dll files (dynamically linked libraries) need to be in the same directory as the application or on the search path. lib files (static libraries) need to be statically linked during linking (the last step of building the application). It's common in Windows so have a library come with both a dll and lib file. In this case, the lib file is an import library containing the information needed to easily link to the dll.
Place the dll file where your application will be built and statically link with the lib file. Go to 'Project->Properties->Link->Input->Additional Dependencies' and 'Project->Properties->Link->General->Additional Library Directories' to specify the static libraries you want to link.
Edit: It seems I misunderstood the question. The question is how to recompile a dynamic library as a static library. You need the source code of the library you are using along with it's Visual Studio Project file. Open the library and in `Project->Properties->General->Configuration Type' change it from Dynamic Library to Static Library.
Beware that Dynamic Library uses the Linker group of properties while the Static Library uses the Librarian group of properties. Changing between these types may cause the project to drop essential linker flags options. Since every library is different, I can't predict what you will have to do work around this. Make sure to backup the project file so you can see the original options and flags.
I had to change the setting for "Static Library" for All Configurations, not just Debug, although it was building in Debug. Not sure what may have caused this. Possibly because the debug and release builds for the library were set to the same folder, it may have been overwriting the debug builds with release builds when building
If .lib files are for static linking and .dll files for dynamic linking why can I specify in C/C++ -> code generation -> runtime library options select multi threaded or multithreaded DLL when building an explicitly static library (ie when making a .lib) or when building a project and linking to a .lib library?
Visual Studio allows you to specify how the CRT is going to be integrated into your project under C/C++->Code Generation->Runtime Library. This project setting controls how C/C++ routines used explicitly or internally (e.g. exception functions or STL routines) are going to be linked to your project.
You can create a static library which uses the CRT dynamically or statically by specifying the /MT or /MD flag during compilation.
Regarding advantages/disadvantages I'm linking this answer which features a pretty good list of points to keep in mind.
One last thing to notice: if your project is going to use multiple static libraries (including your .lib file), you should make sure that this CRT option matches during the linking phase otherwise you might encounter the (in)famous LNK4098 error.
I have written a DLL in Qt. If I try to statically build it (so that you don't need Qt installed in order to use the DLL), it becomes a .lib file. Is there any way to statically build the DLL file without making it a .lib file?
I have two Qt installations. The non-static one creates a DLL file but the static one creates a LIB file.
You need to make sure that your Qt installation is statically built in order to link statically. I would check the Qt license for linking statically though as you may have to open source your project in order to legally link Qt statically in accordance with LGPL.
You want to build a dynamically linked library with dependencies statically linked.
You library will be compiled to be a DLL, but the Qt dependency needs to be statically linked against your library.
I've created a Static Library (no mfc is used in it) in Visual Studio and want to link with it in statically linked mfc project (com-dll actually).
When linking mfc-lib I get a bunch of messages symbol is already defined. This is because I linked standard C++ library twice (once in static library, and other in mfc project).
How do I fix it?
There is a workaround with /FORCE:MULTIPLE, but I think this is a bad decision.
When linking static libraries to a DLL or EXE project, you need to take care, that all projects have been compiled to use the same runtime library. So please set all projects to the same "Use of MFC" and also to the same "Runtime library". If you do not do so, then one project might have been compiled to take the fopen function from the standard CRT while another project might have been compiled to take the fopen function from the MFC. Mixing these is a problem for the linker because he does not know which runtime (and in the example: which fopen) to use.
When linking your DLL or EXE project against another DLL project, this is not a problem. You can have a DLL without MFC usage and link your MFC EXE against that DLL.
If you have a util library that you use very often in different projects, then you might consider setting up different build settings so you can build your library in DEBUG and RELEASE and with and without MFC. Then in your EXE project you can pick the library binary that matches your project settings.
I'm linking to a few libraries in VS2008. If my knowledge of the linker is correct, MTd is for static linking and MDd is for dynamic linking (to a DLL.) My goal is to statically link some libraries and dynamic link others. The project options seems to only have one setting for all libraries in the linker input. How would I do this?
Your project will be given a sensible C Runtime Library default after you set it up, depending on how you answer the New Project Wizard prompts. You can inspect and alter this (if needed) as follows:
right-click the relevant project in Solution Explorer, select Properties
look under Configuration Properties, C/C++, Code Generation, Runtime Library.
Other libraries can be linked however you want, you just specify the library to link to under Linker, Input, Additional Dependencies.
Even if you are linking to a DLL, it will still have a .LIB file (of the correct form for a DLL) to resolve external references, unless you are manually loading the DLL and discovering required function entry points.
You do need to make sure that the LIB files you link to use the same CRT as your app does, or things can go unexpectedly wrong.
No, you're mixing it up. The /MD vs /MT options is only relevant to which CRT version you link. There are two, the static version (/MT) which you should use only if you don't use any DLLs in your project. And the DLL version, a version that every binary in your process can share so that you won't have heap allocation misery. The kind of misery you get into when memory is allocated by one module and freed by another.
Choosing your own libraries is entirely up to you. Mixing and matching is fine, the linker just gets another kind of .lib. An import library instead of a static library. Just keep in mind to use /MD when you use DLLs.
The linker options your describing are for the CRT only. The static version will limit how you share memory between modules.
All other libraries you use will have be linked in based on the .lib files you provide(or not) to the linker.
There are 3 ways to use a MS library
statically link static library (.lib equivelant of an .a archive of .o)
statically link the stub (.lib compiler generated loadlib/getproc) of a dynamic library
manually load a dynamic library (loadlib/getprocaddress)