I'm trying to add PNG support to my application and thus I want to include libpng. I know it needs zlib and thus I downloaded that as well. I went into the png folder/projects/vstudio and I opened the solution. I compiled it and it went just fine. I added some headers from it into my application and I copied the lib files. My program is a dll written in c++ which is later used from C#. When I run it in C# it complains about not finding my dll (tough if I remove the png part it works fine). I've had this problem before and it usually means a dll dependency is wrong.
Now... libpng compiled both some .lib files and some .dll files. The dll files are bigger. My only guess is that it needs the dll files as well but I've seen that people can link to libpng without a dll.
So my questions is: How can I compile libpng(and zlib for that instance) into just static libraries and how can I include those in my projects? I've searched around the internet and I couldn't find anything useful.
To make all your libraries static, you would have to recompile everything "from scratch" as static libraries.
This simply means you should create a set of projects for each library you have in your sequence and set the output type to static library.
After that you should eliminate library dependencies between the libraries themselves (this means you should link the output of some projects to another projects, e.g. if your "libpng" library uses "libzip", it means you should first compile the "libzip" and link that output (static library) to your "libpng" project.
In the very end you would have a big set of static libraries compiled for your platform, which you can use in your projects.
Also to mention, try googling more carefully. I'm sure someone has this done and you would probably need to download a package of .lib files for your platform (I know that very often the "dev" bundle of libraries only includes an import library paired with appropriate .dll file, but there are a lot of enthusiasts like you :)
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I'm fairly new to C++ and I know how to link external libraries in Visual Studio, but I'm not sure how to include them with the .exe file that is made when you build. How do I include a library with that so the other PC doesn't have to have the libraries installed in the same exact location on the disk that I do (or in other words just with the application)? I tried putting the .dll files directly with the .exe but it says it can't locate them.
This depends on the type of linkage that you use for the library. You basicaly have 2 options:
static linking
dynamic linking
When you statically link your program with a library, that library is embedded into the resulting application (exe). So you need to distribute only that resulting application.
Or the library can be linked dynamically. This means that the actual library code will be looked up at runtime (by OS) from dll file (on Windows). In this case you must be sure, that user will have dlls you need on their computer. To see where Windows searches for dlls see this msdn page. Basically you want your dlls to reside in the folder, where your program is, so Widnows can find it. Or if you are using some system libraries (e.g. Direct3D) your user will probably have those dlls already installed.
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
I implemented the SFML library nightly build to my Visual Studio 2013, because the original one is not compatibile with this VS version. I done everything what is needed (added directory to include folder in both Debug and Release, added directory to .dll files), but it can't find the files in program. What else should be done to make this library work? Or should i consider changing Visual Studio to 2010?
You haven't given really to much information so I am just really guessing as to what the problem is.
added directory to .dll files
But that sounds like your problem right there. You don't add the directory that the .dll files are in to your project. The only directories you need to add to the project are the include directory and the library directory.
But anyways I am assuming you are using dynamic linking since otherwise you wouldn't be dealing with .dlls. Now different IDE's require that you place the .dlls in different spots but since you are dealing with VS2013 you need to copy whatever .dlls that you are using into the same folder where your program's compiled executable is (The .exe file).
Another option is to link statically instead of dynamically which I generally prefer to do on small projects but it is really up to the developer which he prefers.
When you link statically you don't need to include any .dlls. What you will need to do is recompile SFML's sources and make sure to build the library so it produces the static library files (They should be named something like sfml-graphics-s-d.lib for debug and sfml-graphics-s-d.lib for release).
Add that library directory which contains the static library files to your project and then link to them .lib files in VS's input window (Remember that -d is for the debug build).
Next you will need to add SFML_STATIC to your preprocessor options on both the release and debug build.
After that you are good to go and don't need to include the .dll files with your project. And again whether you choose to link dynamically or statically is really up to you and the project you are working on but for small projects I would suggest linking statically.
I want to create an executable that I can move to another computer that does not have OpenCV installed.
As such I am trying to statically link all the libraries needed into the executable (Thats what its called right?).
The program compiles just fine and works on my local computer but when I copy it to another computer it complains that it is missing .dll files and won`t execute.
I am using eclipse juno with mingw as compiler on windows 7.
My progress so far:
I have included the libraries needed from opencv\build\x86\mingw\lib into the MinGW C++ linker -> libraries in the project properties.
opencv_core244.dll
opencv_highgui244.dll
opencv_imgproc244.dll
In the original folder these are called:
libopencv_core244.dll.a
libopencv_highgui244.dll.a
libopencv_imgproc244.dll.a
I have set the linker flag in MinGW C++ Linker -> miscellaneous to -static.
I have been searching a lot for answers and have tried a few different things but I`m really stumped by this.
How do you force the compiler in eclipse (MinGW in this case) to link the libraries as static libraries and not as dynamic libraries as it is apparently doing?
1) If OpenCV has been compiled to be used as DLLs, then you can not link statically.
2) Remember when you compile the project for DLL output then you have a .lib file. This .lib file is not actually a static library with code. It is used by the compiler to know the DLL name for class/function definitions. This will need the DLL at runtime.
3) For static linking you need .lib file which compiled as static library. In such compilation there is only one output which is a .lib file. This .lib file can be used for static linking and the code from .lib file is added to your application.
4) I have just compiled one project with VStudio which is a DLL having only one function. I get a DLL and a .lib as output. The size of the .lib is 2kb.
5) When I compile the same project as static library, then I get only one output that is .lib file. Its size is 133kb.
This is almost a year late with the clarification/answer, but hope it can be some use to you or anyone else who comes across this page with the same problem.
While Pruthviraj didn't clearly explain his answer, he had the right idea. By default, the config file for cmake has "BUILD_SHARED_LIBRARY" flag set to true. The .a files that were created simply redirected to the dll files and are in essence useless to statically link in a program.
The easiest way is to rebuild OpenCV with cmake, but make sure the flag "BUILD_SHARED_LIBRARY" is set to false. It is under the Build sub-category in cmake GUI if you are using that.
The new generated make files should produce static libraries only in the lib folder and should properly link opencv statically in your program. Hope it helps!
This question might seem obvious but I am having a lot of trouble with this, and I have ended up having to post here after a lot of searching.
I currently have two windows of Visual Studio open. One is a Win32 Console->DLL project which exports a class, and in the output directory I have:
.dll file
.exp file
.pdb file
.lib file
I have dropped the DLL file into the my other project's output directory, as I do with all DLLs, and that works fine usually. Then, I added the directory into the Linker's library directories.
But unlike most libraries I use, I think I have done something wrong or I misunderstand how this works, I have no .h[pp] files, and so I have no idea how I am supposed to include the functions into my code. I'd rather not have Windows-only hacks (I want to confine that to the DLL project only, so that it can be ported easily).
Can anyone enlighten me as to what I am doing wrong?
There is nothing 'hacky' or 'windows' specific about having .h files available to the other projects. Your .lib file will provide the necessary information to complete the build. See: How do I use a third party dll in Visual Studio C++?
Did you add the .lib file corresponding to the .dll into the other project's directory?
It is the .lib file that is consumed by the linker, not the DLL (which is consumed by the loader at run-time).
A .dll is a shared library, as opposed to a static library (.lib on Windows).
Static library must always be linked when you compile your project, and you can easily call their functions using header (.h/.hpp) files, whereas you have two options for the shared library:
static linking (at compile-time, but the way to do it is different than for a static library)
dynamic linking (at run-time)
I would advise you to read this in-depth article: http://www.codeproject.com/Articles/85391/Microsoft-Visual-C-Static-and-Dynamic-Libraries
See also the wikipedia article: https://en.wikipedia.org/wiki/Dynamic-link_library