I am using VS2010 and
I have a C++ project that is referencing and using an external C library (dll) by having various entries in the VC++ Directories and Linker sections of the project properties.
Right now my project is building but when it starts, a message box appears :
The program can't start because ExternalCLibrary.dll is missing from your computer. [...]
I would like to know how to do in Visual Studio 2010 the the equivalent of
adding "-static-libgcc -static-libstdc++" to your compiler flags.
It seems to be the solution according to:
The program can't start because libgcc_s_dw2-1.dll is missing
Load your project in Visual Studio.
Right click your project and
choose Properties.
Locate the "Linker" portion of the tree on the
left.
Choose All Configurations and All Platforms from the drop down
menus at the top of the dialog.
Put your additional static library
dependencies in the Input -> Additional Dependencies field, semicolon delimited.
If the libs are not on your lib search path, make appropriate
entries in the General -> Additional Library Directories field, semicolon
delimited.
Apply, save, compile, run.
You can't use dll as a static library ( that's why they are called Dynamic-link library ). In order to compile a static library, you'll the source code of that library. Once you have the source code, go to Project settings, General->Configuration Type and set it to Static Library(.lib). Then in your program, you'll need to add that library by putting the library name in Linker->Input->Additional Dependencies
The two flags passed to gcc as per your question tell gcc to link the runtime library statically to an executable or shared library/dll. This is unlikely to be the problem with your issue as the part of the error message you quoted suggests that ExternalCLibrary.dll isn't being built properly.
If the DLL exists, use a tool like dependency walker to determine which dependency of your DLL can't be loaded; that's the likely culprit.
If ExternalCLibrary.dll doesn't exist then you need to find out where you are supposed to get it from, but if your project builds and it's listed in the project as a dependency then my guess is that it's an issue with the loader not being able to find a dependency of this DLL at runtime.
This process is simple, however you need to be aware of several things. The first thing, if your lib is written in C, in the header files of every source containing C functions us the following.
#ifdef __cplusplus
extern "C" {
#endif
// C functions
#ifdef __cplusplus
}
#endif
Once you've done that, compile the library into a static library using the ar rcs [YOUR OBJECT FILES]. The final thing to do is us the c++ compiler link the library with the object files from your project. Now flags are required to link the library.
Related
I am trying to use ICU Unicode in my C++ Project.
I have downloaded the libraries from here, and then linked them by:
Adding the lib64 directory to Properties -> Linker -> General -> Additional Library Directories
Adding the names of all the .lib files into the Input tab.
I then #include "ucnv.h", and the build and run.
The program builds fine, but I get this error message saying I need to put the DLL next to the exe.
I do that, and it runs fine. My questions is
How do I statically link ICU to my project?
What I have tried
I have tried downloading the Master from github, and opening the allinone.sln file, and then setting the following:
Release and x64
Changing the output from DLL to Static Lib
Adding U_STATIC_IMPLEMENTATION to all of the project-preprocessors
I then rebuild, and then add each one of the projects release directories to the Additional Library Directories section of my projects properties, and then also adding the names of the libraries to the Input Section.
Now this actually works for UTF-8, however, for another encoding such as Big-5 most of the functions (and basically all essentials) return NULL.
Also, another reason for a static library is because the DLL I downloaded is over 16MB, which is way too big. On ICU docs they even say that they recommend static linking to reduce size (by removing unneeded)
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
Probably I am missing here something but that is my first time on Windows that I need to link a lib statically so that the executable won't be dependent on a dll.I do it with LIBPNG.
I do it like this:
I added libpng headers : C/C++ -> Additional Include Directories
Added library directory to the linker: Linker - > General ->
Additional Library Directories
Added linker additional dependencies:Linker -> Input
Compile the exe ok.When calling it I am getting :
"The program can't start because libpng16.dll is missing from your
computer."
Which means libpng hasn't compiled into the executable.How do I fix that without reference the whole pnglib project code into my executable project?
On Windows a .lib is a library file, usually this simply contains code that loads a dll, looksup the exported functions and provides wrappers to them. But, you can build the lib differently so that instead of these wrapper stubs, it contains the actual binary code. The operation and structure of the .lib is the same - what code it contains depends on how its built.
So, if you've built libpng16 as a 'dynamic' lib/dll pair then you will need the dll part when you deploy it. If you built it as a 'static' lib only, then you'll get what you want.
The point is - you need to build the lib in the format you want in the first place. It is not possible to take a lib/dll pair and convert it into a static lib, nor is it possible to merge a dll into your executable. (well, not possible after you've built it - perfectly possibly if you change the lib's settings and recompile to produce in static lib form, of course)
vs report a error such as:
can not find xxx.lib
How do I check out why vs need to link xxx.lib? Is there a trace log? My project have not use boost.regex, but vs report a error says can not find regex.lib. So I want to find out which part of code refer to regex
LNK error: LIBCMT.lib: xxx was already defined in LIBCMTD.lib
How do I check why vs also link yyy.lib even this is a debug build? I have 2 projects, they link to same libs, all libs and project itself was /MTd. But one of them will report above error, I think it shouldn't link LIBCMT.lib because it is a release version lib, and another project is OK so the lib file was build correctly
VS can show the link trace?
1) Let's start with how the linker actually knows what to link with. Basically there are 2 categories:
Libraries specified in the project settings in the linker options as additional inputs
Libraries added in code with precompiler directive #pragma comment (generally the same thing as above but people have different tastes)
Otherwise you just get information about missing symbols but not the actual library they are from. What you can do to help is under visual studio linker options set Show Progress to For Libraries Searched (or just /VERBOSE:LIB linker flag), that will actually show you what dependencies are added after each lib is loaded, this also helps with point 2) to see which library loads which run-time.
2) Already mentioned in 1) that you can make the linker show library load progress, otherwise if a dynamic C run-time is used in the external library you are linking against you could use Dependency Walker to examine the dependencies of the library and find if the C run-time dll that is needed is debug or release by 'd' suffix in the dll name. If the library is already linked with static run-time then I guess only the linker errors will warn you. But I think that most serious libraries are correctly packed and structured so that you will be able to tell which files contain the debug version and which the release. If the library has only release version, well than that's another story. But i mean still, you can reconfigure the Debug configuration of your project to actually link against the release run-time to satisfy the external library, of course this prevents some debugging features, debug heap, etc.
For the missing boost regex library problem, I think the cause is due to boost's default autolink behaviour. If you include one of the headers of some of the boost libraries (not all of them, but regex is one of them), then these will cause Visual Studio to automatically link against the library. It uses a special pragma of the form:
#pragma comment(lib, "regex")
This has the effect of automatically adding a flag to the linker command. However, it's only picked up during compilation and so you won't see it in the project properties. In the case of boost, the solution to this is quite simple - find boost/config/user.hpp and uncomment the line
#define BOOST_ALL_NO_LIB
This will turn off the autolink behaviour for all libraries. Alternatively you can use #define BOOST_REGEX_NO_LIB to change this just for the regex library.
To solve the second problem, you need to find out which library is linking against the release build. Try selecting all projects in the solution and open Properties -> C++ -> Code Generation. You will probably find that the Runtime Library setting will be blank (because the option is different for some of the libraries. Force it to the correct threaded/single-threaded Debug option and rebuild.
In Eclipse I have created two libraries. One of them is shared another one is static. I have compiled them in Eclipse and as a result a Debug folder was created (for both libraries) and these folders contain make-files as well as object files (*.o) and dependency reference file (*.d). In addition to that, the static library contains an *.a file.
Now I create a new project and what to use these library in this project. Normally, when I use a library I type #include <libraryname>. But if I use #include <mylibraryname> it does not work (I get unresolved inclusion). And this is not surprising because Eclipse should somehow know where my library is located. So, my question is how can I inform Eclipse about the locations of my libraries.
ADDED As recommended I do the following sequence "Project -> Properties -> C/C++ Build -> Settings -> Tool Settings -> GCC C++ Linker -> Libraries". Then, in the "libraries(-l)" filed I add "StaticList" (because I have "libStaticList.a" file) and in the "Library search path (-L)" filed I give the full name of the directory where my "libStaticList.a" is located. Then I click Apply and OK. But it does not help. Eclipse does not like #include <StaticList>. It complains: "Unresolved Inclusion..".
#includeing headers only makes the compiler aware that the functions in those headers exist. The actual implementation of those functions needs to be linked in by the linker. That's where the library (.a) files that you built come in. Check out this thread for an example on how to link in your libraries using Eclipse.
I think you need to #include "yourlibrary.cpp" (between double quotes) instead of < >.