I have a DLL that I compiled from source (gdal). I have a simple C++ Win32 console project that has one source file, but I want to link against that DLL. Currently, when I try to run the project, it compiles correctly, but says that it cannot find the DLL. If I move the DLL to the same directory as the DLL, the exe will run. Is there a way to make my output EXE include the DLL so that I can just move one file to another system and run it without having to send the DLL with the exe.
How can I make this happen in VS2010?
Unless you had the original source code for the .dll, recompiled as a static library (.lib) and then statically linked to it, I don't believe there's a way to "include" the dynamically linked library inside your executable.
You need the DLL in the path, or in the current directory for your application to run. That is how it works with DLLs.
With static libraries, the linking embeds the library code into your application. If you cannot or do not want to have the DLL available, you could change your DLL to a static library.
Since you are compiling it from source you can just add the source files to your project and build it right into your executable.
You could create a Post-Build Event in the Visual Studio project that runs a script to copy the DLL to the path of the executable.
Then, when you deploy your application, an installer would be able to take care of the DLL management for you.
Related
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've downloaded and compiled zlib, and I am statically linking zlibwapi.lib to my C++ project on Visual Studio 2015.
However, if I don't use the dll and launch my program, it complains about it:
"The program can't start because zlibwapi.dll is missing from your computer."
With the DLL though, no error message shows up and the program works fine.
Is there any way I could use my program without the need of zlibwapi.dll?
I've done this with MSVC 10. I created a separate project for zlib and built it as a static library (.lib), which I then added to my main application project. The projects are not in the same workspace. I did have to build a separate copy of zlib.lib for 32-bit and 64-bit builds of my app, and the app itself uses MFC in a dynamic DLL. Everything links just fine, and zlib is not in a DLL.
I thought this should be straightforward but I am running into a bunch of linker errors like so:
Error 1 error LNK1104: cannot open file '...\Debug\Utils.lib' ...\LINK
where Utils is one of the C++ projects I want to keep as DLL.
If I change Configuration Properties->Configuration Type to Static Library(.lib) everything compiles and runs fine, but if I use .dll then its not working.
The whole solution is native C++ with the main project being a win32 console application.
Perhaps your library (Utils.lib) is not assembled as DLL and changes in console application project (that uses library) will not help.
Read carefully MSDN to see features of DLL's creation and usage.
It you try to link a .lib against another .lib, it doesn't really link. Instead, this instructs the final link to use both libraries.
For a DLL, this can't work, as the runtime linker cannot link the original .LIB. That means the link has to happen when the DLL is compiled.
As a result, a DLL project needs to have the .LIB directories set right.
I'm trying to understand what exactly all of these are and how they relate to each other (and most importantly, how to install them).
From what I've read, LIBs are libraries linked during the compilation of my project and DLLs are libraries linked during the runtime of my project.
So for me to use a LIB, I have to have the actual .LIB file somewhere in my computer, go to Project -> Properties -> VC++ Directories and add the path to the file in the Library Directories, and after this I have to go to Linker -> Input -> Additional Dependencies add the .lib name in there, and finally I need to type #include in my code, right?
So, some questions:
When I finish and build the release of my program, will the .exe only run if the target platform has the .lib installed in their PC as well? If yes, what steps do I need to do to make sure the .lib goes with the .exe?
When I get the source of a open source project, if I add them (using Add Existing Item...) to my project, can I use them just by using #include as if the files were mine and it would be the same as having the .lib installed? Or do I need to install the .lib file and still use these source files?
I have a project using OpenGL and I linked to glew32.lib, but I don't have the lib or any new directory added in the VC++ Directories, so I think this means I must've installed the .lib in the system folder or somewhere where the Visual Studio won't ask for another directory, should I worry about this when releasing a project?
How the above questions relate to DLLs and is there any reason why should I use DLLs over LIBs or the other way around?
I'm starting to use more and more libraries and I noticed I just dragged, copied and included it everywhere so I could use them but never really understood how they "fit" in the project. Especially those open source libraries where they provide so many files and I don't really know what to do with them...
You don't need to have LIB files along with your EXE file for running in another computer, LIB files are static files and DLL files are dynamic. So when you compile all static codes will be included in your EXE file, but DLL files will be loaded and used dynamically in runtime, so you just need to have your DLL files with your EXE file. This way, your code will work and run properly in other computers.
Just adding another project is not enough, you need to compile them and generate LIB files out of them. Then you add the generated LIB file to your final project and include external projects in your final binary. If you are compiling multiple projects together in a solution, you'll need to set project build order in solution properties in VS.
No, that's OK. It seems you've put LIB files in right folder and you don't need to have LIB file with your EXE file to run it in other computers.
DLLs are dynamic libraries, so you need to have them with your application. Installers usually install EXE files with DLL files in the same folder, so your app will run properly, but no need to include LIB files at all.
Also you can include LIB files like this:
#pragma comment(lib, "glew32.lib")
So you don't need to do it in project settings, but assuming you have your LIB file in "Library Directories" path.
Using DLL files can be done in two ways:
One is linking your application to DLL file and having DLL file's function entry in your EXE file's import table:
like using
#include <windows.h>
then
GetWindowsDirectory(windir, MAX_PATH);
So you'll have GetWindowsDirectory API entry in your EXE file's Import Table.
Also you can do it dynamically:
hinstDLL = LoadLibrary("kernel32.dll");
if (hinstDLL != NULL)
{
func_GetWindir = (DLLPROC) GetProcAddress(hinstDLL, "GetWindowsDirectoryA");
...
There is not much difference, only difference is:
In first method, as it's in your EXE file's Import Table, if there was no kernel32.dll or there was no GetWindowsDirectory entry in kernel32.dll, your EXE will not run at all, it will show a critical error and will not run. But in dynamic way (second way), your app will run, but as soon as your code try to use GetWindowsDirectoryA API, it will fail. You will have 0x00 in func_GetWindir. If you attempt to call it, then program will crash.
I have a program that uses libcurl library. After code compiles in order for the .exe file to work I have to put libcurl.dll in the same folder as exe file. Is there a way to add this libcurl.dll file implicitly into the .exe file so it would not require the dll file?
You can add any payload to an executable image as a custom resource, including other binaries (see Creating a New Custom or Data Resource). During application startup you will have to extract the .dll and save it to disk. This also requires that you mark the library imports as /DELAYLOAD (see Specifying DLLs to Delay Load). Otherwise the loader will fail due to unresolved imports.
A more natural solution to your problem would be to compile cURL as a static import library and link to it statically. This compiles the libcurl code into your final executable image. Instructions on building a static library can be found at How to build cURL static library with SSL support on Windows.
You could try using open-source pefrmdllembed to merge the DLL into your EXE file.
Commandline: pefrmdllembed.exe -impinj myprogram.exe libcurl.dll myprogram_withcurl.exe
It will generate new "myprogram_withcurl.exe" that you can ship instead of the original EXE. Should work witb most DLLs.