I've been recently trying to use libVLC - functionality of great, codec-less VLC media player enclosed in form of DLL library. By the way I've came across a great article: GenerateLibFromDll and now I know how to generate LIB file for any DLL library! Here is detailed description of the problem:
visual studio generate lib file from dll
When you have a DLL library you want to use in your C++ code, you may do it dynamically by using LoadLibrary and GetProcAddress functions from WinAPI, but it's more convenient to do it statically. But it's not enough to just #include signatures of library functions and use them in your project. You also need to link with some LIB file, even if the file is not a real static library with compiled code, but only a few-kilobyte-long list of imported functions. I believe that's just another flaw of C++ language, because other languages like for example C# don't need this even when importing functions from native DLL libraries.
If you have some SDK prepared for Visual C++ or compile the library by yourself, you also get the LIB file next to DLL. But if you have only the library, that article shows following steps to generate matching LIB:
And there you have it! The so much required LIB file generated from DLL library. You only need signatures of these functions with proper parameters and return values declared in some H header file and you can successfully use your DLL by linking with LIB file created by yourself :)
I am trying to create an application in visual studio that will be able to access a .dll file that already exists. I need the application to call up routines. I also have a header file that already exists.
But when I build the solution, the only relevant output file I see is a DLL file; I don't see any LIB file getting generated. I looked in the project directory and all subdirectories (Release and Debug).
OK, so I found the answer from -c-does-not-generate-lib-file-for-a-dll-project/ says that this problem was caused by not exporting any symbols and further instructs on how to export symbols to create the lib file. To do so, add the following code to your .h file for your DLL.
When the MATHLIBRARY_EXPORTS macro is defined, the MATHLIBRARY_API macro sets the __declspec(dllexport) modifier on the function declarations. This modifier tells the compiler and linker to export a function or variable from the DLL for use by other applications. When MATHLIBRARY_EXPORTS is undefined, for example, when the header file is included by a client application, MATHLIBRARY_API applies the __declspec(dllimport) modifier to the declarations. This modifier optimizes the import of the function or variable in an application. For more information, see dllexport, dllimport.
Whether it's your own or from a third-party, your client app project needs several pieces of information to use a DLL. It needs to find the headers that declare the DLL exports, the import libraries for the linker, and the DLL itself. One solution is to copy all of these files into your client project. For third-party DLLs that are unlikely to change while your client is in development, this method may be the best way to use them. However, when you also build the DLL, it's better to avoid duplication. If you make a local copy of DLL files that are under development, you may accidentally change a header file in one copy but not the other, or use an out-of-date library.
To avoid out-of-sync code, we recommend you set the include path in your client project to include the DLL header files directly from your DLL project. Also, set the library path in your client project to include the DLL import libraries from the DLL project. And finally, copy the built DLL from the DLL project into your client build output directory. This step allows your client app to use the same DLL code you build.
You can also enter a relative path from your client source files to the folder that contains the DLL header files. If you followed the directions to put your client project in a separate solution from the DLL, the relative path should look like this:
Double-click in the top pane of the Additional Library Directories dialog box to enable an edit control. In the edit control, specify the path to the location of the MathLibrary.lib file. By default, it's in a folder called Debug directly under the DLL solution folder. If you create a release build, the file is placed in a folder called Release. You can use the $(IntDir) macro so that the linker can find your DLL, no matter which kind of build you create. If you followed the directions to put your client project in a separate solution from the DLL project, the relative path should look like this:
Recently I was working with a 3rd party win .dll file and having trouble to compile my code as I did not have required .lib file. Microsoft Visual Studio provides a way to create necessary .lib file form .dll file. Follow the steps given below to create .lib file from .dll file.
To avoid installing and fighting against MSYS and Cygwin, you can just extractexported symbols from libvlc.dll to generate a .lib (libvlc.lib) and link your program against it.And all of this using only with Microsoft Visual Studio Tools!
Following instructions from the doc: Libraries PackageCompiler, I have successfully built julia package to DLL. However, I did not find a way to link the final executable in my Visual Studio C++ project: I got LNK2019 and LNK1120 errors related to unresolved external symbols, because .lib files are missing (bug or feature?). Manually generating .lib by MSVC lib.exe does not work (following Building libraries on Windows generates DLLs, but not the corresponding import libraries Issue #687 JuliaLang/PackageCompiler.jl GitHub).
Everything I describe here will apply to the C\C++ interface of OpenCV. I start out from the assumption that you have read and completed with success the Installation in Windows tutorial. Therefore, before you go any further make sure you have an OpenCV directory that contains the OpenCV header files plus binaries and you have set the environment variables as described here Set the OpenCV environment variable and add it to the systems path .
You can start a Visual Studio build from two places. Either inside from the IDE (keyboard combination: Control-F5) or by navigating to your build directory and start the application with a double click. The catch is that these two aren't the same. When you start it from the IDE its current working directory is the projects directory, while otherwise it is the folder where the application file currently is (so usually your build directory). Moreover, in case of starting from the IDE the console window will not close once finished. It will wait for a keystroke of yours.
1) Building PortAudio with DirectSound support requires the files dsound.h and dsconf.h. Download and install the DirectX SDK from =en&FamilyID=3021d52b-514e-41d3-ad02-438a3ba730ba to obtain these files. If you installed the DirectX SDK then the DirectSound libraries and header files should be found automatically by Visual Studio/Visual C++. If you get an error saying dsound.h or dsconf.h is missing, you will need to add an extra include path to the Visual Studio project file referencing the DirectX includes directory.
1) Make sure your project doesn't try to build any ASIO SDK files. If you're using one of the shipped projects, remove the ASIO related files from the project. In the shipped projects you can find them in the project tree under portaudio > Source Files > hostapi > ASIO > ASIOSDK
I dont often create a new Fortran project but when I did, I made a DLL, it compiled and linkedbut did not generate a .lib file.I have the module statement:module K3_NN_Utilitiesand the DLLEXPORT statements:DEC$ ATTRIBUTES DLLEXPORT, ALIAS: 'WriteSignalToFile' :: WriteSignalToFileDEC$and the properties shows that a LIB should be created:/OUT:"C:\\agr_dev\\Ver1.0\\K3_NN_Utilities\\K3_NN_Utilities\\x64\\Debug\\K3_NN_Utilities.dll" /VERBOSE /NOLOGO /MANIFEST /MANIFESTFILE:"C:\\agr_dev\\Ver1.0\\K3_NN_Utilities\\K3_NN_Utilities\\x64\\Debug\\K3_NN_Utilities.dll.intermediate.manifest" /DEBUG /PDB:"C:\\agr_dev\\Ver1.0\\K3_NN_Utilities\\K3_NN_Utilities\\x64\\Debug\\K3_NN_Utilities.pdb" /SUBSYSTEM:CONSOLE /IMPLIB:"C:\\agr_dev\\Ver1.0\\K3_NN_Utilities\\K3_NN_Utilities\\x64\\Debug\\K3_NN_Utilities.lib" /DLLWhat is it that triggers a LIB file to be created ?
!DEC$ ATTRIBUTES DLLEXPORT, ALIAS: 'ReadSignalDataFromFile' :: ReadSignalDataFromFileThe subroutine name was NOT the same as the DLLEXPORT name.No error was generated but no *.lib was create either.Changed DLLEXPORT to match subroutine and suddenly the *.lib file was created.
Adds a library target called to be built from the source fileslisted in the command invocation. The corresponds to the logical target name and must be globally unique withina project. The actual file name of the library built is constructed basedon conventions of the native platform (such as lib.a or.lib).
will include objlib's object files in a library and an executablealong with those compiled from their own sources. Object librariesmay contain only sources that compile, header files, and other filesthat would not affect linking of a normal library (e.g. .txt).They may contain custom commands generating such sources, but notPRE_BUILD, PRE_LINK, or POST_BUILD commands. Some native buildsystems (such as Xcode) may not like targets that have only object files, soconsider adding at least one real source file to any target that references$.
If an interface library has source files (i.e. the SOURCEStarget property is set), or header sets (i.e. the HEADER_SETStarget property is set), it will appear in the generated buildsystemas a build target much like a target defined by theadd_custom_target() command. It does not compile any sources,but does contain build rules for custom commands created by theadd_custom_command() command. 2ff7e9595c
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