I can't find anything about how to make a C DLL in Code::Blocks. Whenever I try and look it up it shows links to using C++ DLLs in managed programming languages. And Code::Blocks doesn't give an option for a C DLL. What do I do?
File->New->Project to show this dialog:
Then select Dynamic Link Library and away you go.
In Code::Blocks you create a new project, then select Dynamic Link Library (note: you can also, more easily create a Static Link Library, which is also available) and follow the prompts (as stated above).
In order to change your files from C++ to C, make sure the extension is .c not .cpp. Then you can right click on the included .c files (in the left column), select properties then under the Advanced tab you can change the compiler variable from "CPP" to "CC" and it will compile it using the C compiler. You will need to do this with each file in your project if you initially loaded them as CPP files. Edit: The COMPILER doesn't care about the filename extension, but the IDE you are using (Code::Blocks) DOES. The IDE will choose which compiler to use (GCC for C, and G++ for C++) based on the filename extension. It will choose the C++ compiler if your filename ends in .cpp, where as it will choose the C compiler by default if the extension ends in .c.
The Static Library option (further down the list on the selection screen) is an easier option if having a DLL is not that important to you. You simply load in your files, compile them and you're done. You don't have to redo your functions in any way or have a special header for it. It will create a library for you with the .a extension you can then link to your projects. The beauty is you won't need to provide a DLL file separately.
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I need to extract source code for a function from the existing C library (the library is open source). The problem is that functions are created using macros in header files, and when I write a test project and link the library to it the debugger points me to that header file on 'go to definition' action. I have the source code of the library and I guess i need to build it together with my test code (maybe this is not correct, I am not sure). Any advice on how to proceed, what to use? Thank you.
I need to extract source code for a function from the existing C library (the library is open source).
Several C compilers are themselves open source. Both GCC and Clang are (and so is tinycc). So you legally could improve them (but that could take months of work).
In addition, recent GCC versions (e.g. in july 2020, GCC 10) accept plugins. Your GCC plugin could work on some internal GCC representations (e.g. GIMPLE, GENERIC) so will know about functions (even obtained by preprocessor expansion).
You could also consider using some open source static program analyzers, such as Frama-C or Clang static analyzer.
PS. Take into account open source license issues (legal ones). I am not a lawyer (and you might need to ask one, if you mix various software of different open source licenses).
Please don't answer this as a "How do I cross-compile on Linux for Windows" question, I solved that part. I need some specific instruction on configuring Netbeans. Thank you.
I'm developing a set of C functions that I want to distribute as a .dll on Windows, and a .so on Linux. (This is going to be used from java as a JNI library, but that's irrelevant to the question).
Development environment is Netbeans 8.2.
I have gcc and mingw installed, and compiling my source code for both targets works.
However, I want to create NetBeans configurations "Linux-Release" and "Windows-Release", with Linux-Release using gcc to create the .so file, and Windows-Release using x86_64-w64-mingw32-gcc. So I created a Mingw tools collection that refers to the mingw versions of the C compiler:
In my project properties, I created a Windows_Debug configuration, and told it to use the Mingw tool collection:
I can use this configuration to get a working Dll. However, the output file will be put into the dist/Windows_Debug/Mingw-Linux directory (not dist/Windows_Debug/Mingw-Windows as I'd like), and it's put there with a .so extension, not .dll. I can load this file on Windows when I rename it to .dll, but this will horribly confuse anyone I want to collaborate with.
Naively messing with the CND_DLIB_EXT macro in the generated Makefiles doesn't help at all, they just get overwritten.
I guess I have to either tell Netbeans that the Mingw Tool Collection compiles to Windows, or that the Windows_* configurations compile to Windows, so Netbeans sets the correct values for CND_* and the default output Macro
${CND_DISTDIR}/${CND_CONF}/${CND_PLATFORM}/libSMAQSJni.${CND_DLIB_EXT}
in the linker part of Project Properties works again. (Of course, as a workaround, I could just remove the variables from the macro, and replace them with appropriate constants, but I want to do this "right". I haven't found a way to tell Netbeans "this compiles to Windows" anywhere though, neither in the GUI nor in any of the config files. So, how do I do this?
Starting C and developing on Windows XP... Do the libraries I include (if personal ones) have to be in a certain directory? Or will the computer's contents be indexed to find them?
Thanks
They can be in any directory and the won't be indexed. You can pass a list of "include directories" to your compiler, which will search for headers in these directories. Likewise, you can pass a list of "library directories" to your linker where .lib files will be searched for. The specifics of how to pass these parameters to your compiler or linker depend on the compiler or IDE you are using.
The short answer is that you can just place the libraries (i.e. DLL files I presume) in the same directory as the executable file and they will be found.
The long answer is very much longer indeed, but for now you can get away with just knowing the above!
They can be in any directory you want, the linker just needs to know where there are when the executable is created. If you're using a command line compiler, like gcc, you use an option like "-L{directory}" and "-l{library file name}" to specify where to find libraries you want to include in your compile. This can vary with each compiler, so you have to look at the manpages/help for each compiler (but this is pretty common).
Generally almost nothing about 3rd party (or personal) libraries is automatically found by C compiler toolchains.
Depending on your toolchain, you'll need to perform some configuration so the compiler will be able to locate the headers for the library, as well as some configuration for the linker to locate the libraries.
If the program is built by statically linking the libraries, you generally won't need to do anything special to locate the libraries at runtime (since they're part of the executable). If the libraries are dynamically linked, then you need to ensure that the library is in the appropriate place at runtime (which might be as simple as making sure that it's in the same directory).
Unfortunately, each compiler has it's own way of performing this configuration (which might also differ depending on whether you want to use an IDE or not), so details would depend on what specific compiler you're interested in using.
My executable needs zlib1.dll to run,
and I need to keep them together now and then.
How can I merge it into the executable to save the trouble?
I'm using cmake to build the executable.
UPDATE
zlib1.dll is not directly included by my programe,but required by libpng14-14.dll(one dll of the gtk bundle)
It sounds like you want to link statically so that your program does not require the presence of zlib1.dll in order to run. But zlib1.dll is a dynamic link library (that's what DLL stands for!), so you can't link it statically. The first thing you need to do is find a static version of this library. On windows, it will normally end with the .lib extension.
I'm not familiar with cmake, so I'll let someone else answer the part of the question about how to make cmake use the static library, once you have both.
Sorry there is no way to mix it. Either you must compile and link statically or dynamically. I tried it - it does not work.
So if libpng.dll needs a zlib.dll you can't turn zlib into a static library. You have to also compile libpng as a static library.
I've done this a few times, the makefiles from PNG, ZLIB, (and also the JPEG, TIFF image format libraries) are pretty good. If you need more then 30min to figure out what to do, you should look at it as a good training on your C makefile skills.
please, could someone explain to me a few basic things about working with languages like C? Especially on Windows?
If I want to use some other library, what do I need from the library? Header files .h and ..?
What is the difference between .dll and .dll.a.? .dll and .lib? .dll and .exe? What is .def?
Does it matter how was the library compiled? I mean, is it possible to use, on Windows, a C++ library compiled by VC from within my C code compiled by MinGW?
To use another library, what is preferred way? LoadLibrary() or #include <>?
There are some libraries which only provide the source code or .dll - how to use such libraries? Do I have to recompile them every time I rebuild my project?
How do I create one big .exe? Is this called "static linking"?
How to include some random file into .exe? Say a program icon or start-up song?
How do I split my huge .c into smaller ones? Do I need to create for every part a header file which then I include in the part with WinMain() or main()?
If there is a library which needs another library, is it possible to combine these two into one file? Say, python26.dll needs msvcr90.dll and Microsoft.VC90.CRT.manifest
What happens if I don't free previously allocated memory? Is this going to be cleaned up if the program (process) dies?
Well, so many question... Thanks for every info!
1: If I want to use some other library, what do I need from the library? Header files .h and ..?
... and, usually a *.lib file which you pass as an argument to your linker.
2: What is the difference between .dll and .dll.a.? .dll and .lib? .dll and .exe? What is .def?
This might be useful: Static libraries, dynamic libraries, DLLs, entry points, headers … how to get out of this alive?
3: Does it matter how was the library compiled? I mean, is it possible to use, on Windows, a C++ library compiled by VC from within my C code compiled by MinGW?
Yes, it matters. For interop between compilers, the normal way is to use a C-style (not C++-style) API, with well-defined parameter-passing conventions (e.g. __stdcall), or to use 'COM' interfaces.
4: To use another library, what is preferred way? LoadLibrary() or #include <>?
#include is for the compiler (e.g. so that it can compile calls to the library); and LoadLibrary (or, using a *.lib file) is for the run-time linker/loader (so that it can substitute the actual address of those library methods into your code): i.e. you need both.
5: There are some libraries which only provide the source code or .dll - how to use such libraries? Do I have to recompile them every time I rebuild my project?
If it's only source then you can compile that source (once) into a library, and then (when you build your project) link to that library (without recompiling the library).
6: How do I create one big .exe? Is this called "static linking"?
Yes, compile everything and pass it all to the linker.
7: How to include some random file into .exe? Say a program icon or start-up song?
Define that in a Windows-specific 'resource file', which is compiled by the 'resource compiler'.
8: How do I split my huge .c into smaller ones? Do I need to create for every part a header file which then I include in the part with WinMain() or main()?
Yes.
9: If there is a library which needs another library, is it possible to combine these two into one file? Say, python26.dll needs msvcr90.dll and Microsoft.VC90.CRT.manifest
I don't understand your question/example.
10: What happens if I don't free previously allocated memory? Is this going to be cleaned up if the program (process) dies?
Yes.
If I want to use some other library, what do I need from the library? Header files .h and ..?
You need header .h or .hpp for C,C++ although some languages don't require header files. You'll also need .a, .so, .dll, .lib, .jar etc files. These files contain the machine code that you linker can link into your program. Goes without saying that the format of library is must be understood by you linker.
What is the difference between .dll and .dll.a.? .dll and .lib? .dll and .exe? What is .def?
dll and .a are library files, that contain code components that you can link into your own program. a .exe is your final program into which .a or .dll has already been linked.
Does it matter how was the library compiled? I mean, is it possible to use, on Windows, a C++ library compiled by VC from within my C code compiled by MinGW?
Yes, it is important that the library that you are using is compatible with your platform. Typically Unix libraries will not run on windows and vice versa, if you are using JAVA you are better off since a .jar files will usually work on any platform with JAVA enabled (though versions matter )
To use another library, what is preferred way? LoadLibrary() or #include <>?
include is not a way to use a library its just a preprocessor directive telling you preprocessor to include a external source file in your current source file. This file can be any file not just .h although usually it would be .h or a .hpp
You'll be better off my leaving the decision about when to load a library to you runtime environment or your linker, unless you know for sure that loading a library at a particular point of time is going to add some value to your code. The performance cost and exact method of doing this is platform dependent.
There are some libraries which only provide the source code or .dll - how to use such libraries? Do I have to recompile them every time I rebuild my project?
If you have source code you'll need to recompile it every time you make a change to it.
however if you have not changed the source of library in anyway there is no need to recompile it. The build tool like Make are intelligent enough to take this decision for you.
How do I create one big .exe? Is this called "static linking"?
Creating a static .exe is dependent on the build tool you are using.
with gcc this would usually mean that you have to you -static option
gcc -static -o my.exe my.c
How to include some random file into .exe? Say a program icon or start-up song?
Nothing in programming is random. If it were we would be in trouble. Again the way you can play a song or display an icon is dependent on the platform you are using on some platforms it may even be impossible to do so.
How do I split my huge .c into smaller ones? Do I need to create for every part a header file which then I include in the part with WinMain() or main()?
You'll need a header file with all your function prototypes and you can split you program into several .c files that contain one or more functions. You main files will include the header file. All source files need to be compiled individually and then linked into one executable. Typically you'll get a .o for every .c and then you link all the .o together to get a .exe
If there is a library which needs another library, is it possible to combine these two into one file? Say, python26.dll needs msvcr90.dll and Microsoft.VC90.CRT.manifest
Yes one library may require another library however its not advisable to package different libraries together, you may be violating the IPR and also for the fact that each library is usually a well define unit with a specific purpose and combining them into one usually doesn't make much sense.
What happens if I don't free previously allocated memory? Is this going to be cleaned up if the program (process) dies?
Again depends on the platform, usually on most OS the memory will be recovered after the program dies but on certain platforms like an embedded system it may be permanently lost.
It always a good idea to clean up the resources your program has used.
In all seriousness, the place to go to learn how to run your local environment is the documentation for your local environment. After all we on not even know exactly what your environment is, much less have it in front of us.
But here are some answers:
1. You need the headers, and a linkable object of some kind. Or you need the source so that you can build these.
3. It matters that the library is in a format that your linker understands. In c++ and perhaps other languages, it also needs to understand the name mangling that was used.
6. Forcing all the library code to be included in the executable is, indeed, called "static linking".
7. There is at least one StackOverflow question on "resource compilers".