I am new to C programming.
I was trying to use the pthread API to write some concurrent program.
I downloaded eclipse IDE for C/C++ Developers, MinGW. I have put all the library, header files into the corresponding location of the MinGW file.
When I tried to build the project, there is always an error "cannot find -lpthread", what happened?
I have added the "-pthread" to the GCC compiler.
I have searched a lot in Google but seems no one have similar problem as me.
The answer to this question by someone who is also missing MinGW pthread library should help you out! Essentially the issue is that the MinGW installer script might not download the lpthread library upon installation. Quoted from link:
Just run and open MinGW Installation Manager, which should be pre-installed with MinGW, select "All Packages" on the left panel, and on the right panel, search for "mingw32-pthreads-w32" packages and install them.
I downloaded eclipse IDE for C/C++ Developers, MinGW.
MingGW uses the Windows API. The Windows API does not provide PThreads.
You need to install PThreads for Win32 to have PThreads available under Windows, and with this available under MinGW.
Eclipse is not configured to put the -pthread argument in the gcc compilation. To solve this, go to the Menu:
view sourceprint?
1.Project -> Properties
From the bar on the left:
view sourceprint?
1.c/c++ build -> GCC C Compiler -> Miscellaneous
Add the “-pthread” argument into the beginning of the “Other Flags” Also go to:
view sourceprint?
1.c/c++ build -> Settings -> GCC C Linker -> Libraries
And include the “pthread”library into the other libraries. Click Apply and rebuild the project. Pthreads must work now.
See the question on mingw.org. I ended up with adding 'C:/cygwin/lib' to the settings for the "Library search path (-L)" at properties >> c/c++ build >> settings >> MinGW C Linker >> Libraries.
Related
I am a relatively inexperienced C developer with no previous experience in integrating libraries made by other developers into existing projects.
Basically, I need a means of parsing JSON data in an AVR microcontroller for a university project. To this end I attempted to download and integrate jansson (https://github.com/akheron/jansson) into my existing build of the microcontroller code. I am working with Atmel Studio in Windows 10, but I have also installed Code::Blocks with MinGW GCC (on the same Windows 10 installation) for the purpose of building the library, and to attempt to integrate the library into a native Windows application. So far, neither has been successful, and I get the same errors. All of the online resources I've found so far have been to basic to be useful, or well beyond my comprehension.
This is what I have done thus far:
I began by attempting to build the software and then integrate it into an existing project per the instructions in https://jansson.readthedocs.io/en/2.11/gettingstarted.html. I installed CMake, built the project files for Code::Blocks with cmake.exe -G “CodeBlocks - MinGW Makefiles”, then opened the project and built everything. A few of the targets (I believe related to testing) failed to build, but jansson itself built and output libjansson.a to the \lib\ directory, so I didn’t think too much of it.
That is as far as I’ve been able to get. In both Atmel Studio and Code::Blocks, I do the same thing: add jansson.h to the relevant include paths, add #include “jansson.h” to all of the relevant files, and add libjansson.a as a library in each IDE’s respective linker options. I’ve tried various things like adding and removing flags to the linker, but the output is always “cannot find -ljansson”, “undefined reference to ‘json_object_seed’” (which is a function in the API I’m calling for no reason other than to see if the project has built properly) and/or “ld returned 1 exit status”.
I cannot help but feel as if the issue is with the line “cc -o prog prog.c -ljansson” in the documentation linked above. I really just don’t understand how to set up the linker properly to get the project to build.
If anyone could give some insight into what I’m doing wrong/the correct way to link this library I would appreciate it a lot.
The library itself should be built with appropriate toolchain. I assume that you built your library twice, one version using MinGW toolchain and other with avr-gcc toolchain.
If you compile target application and linker cannot find library, then try to add path of directory that contains *.a file of library to linker settings (linker search path). Let's say you have: /path/to/lib/libjansson.a
In Code::Blocks: Project → Build options → Search directories → Linker add /path/to/lib/. Then it should link with include path set, for example: cc -o prog prog.c -ljansson -L/path/to/lib/
In Atmel Studio when you add a library in Solution Explorer → Libraries → Add Library it should automatically add library search path to linker options. If you check Project → Properties → AVR/GNU Linker there should be (between other options): -Wl,-ljansson -Wl,-L"/path/to/lib/"
If you copied library files (libjansson.a and jansson.h) to your application's project directory, it will be convenient to use relative paths to library files.
Please note: Although I'm specifically talking about the Eclipse CDT plugin, I'm almost 100% confident that any Windows/C/MinGW programmer can answer this question.
I'm on Windows 7 and am trying to write and compile a simple "Hello, C!" C application using Eclipse's CDT plugin. I'm reading their docs which state that having GCC installed is a prerequisite.
I just installed MinGW, making sure to include the following packages:
mingw-developer-toolkit
mingw32-base
mingw32-gcc-g++
msys-base
Back in the CDT docs (under the section titled Windows configuration), it states that I need to add g++, make and GDB to my PATH.
I'm wondering where MinGW installs these utilities, so that I can add them to my system PATH, and make the Eclipse CDT recognize their location at startup.
When using the Eclipse CDT plugin, you need GCC and its 3 specific utilities installed locally. These three utilities are: g++, make and gdb.
On Windows you can choose to install these utilities via Cygwin or MinGW. For a MinGW-based solution, go to their site and download the MinGW Package Manager. Then open the manager and install the following packages:
mingw-developer-toolkit
mingw32-base
mingw32-gcc-g++
msys-base
Then go to File >> Apply Updates and apply them. This will install the 3 utilities to the following directories on your machine:
C:\MinGW\bin\g++
C:\MinGW\bin\gdb
C:\MinGW\msys\1.0\make
Add these 3 binaries to your system PATH, restart Eclipse and you are all set.
I have install the C/C++ CDT Version of Eclipse.
After making a HelloWorld.c file and get the code in there I get an error of "Launch failed. Binary not found".
I found in google that my Eclipse miss the compiler and I install MinGW on my computer and add the path to env variables (tested it with "gcc -v" in cmd and succeded).
But poorly it get the same Launch Failed error - any ideas, what step I forgot?
Some things to check:
1.) MinGW tools are installed as well. Make sure you have the C compiler and the Make program
2.) Check your Environment variables. Make sure both the compiler and Make are on the path.
3.) Eclipse is a temperamental beast at times, don't lose heart :-)
4.) If you're looking for a good IDE (without care for ideological concerns), might be worth looking at Bloodshed C++ IDE and Visual C++ 2010 express (or whatever they call their free version).
5.) Check the options menu in Eclipse to make sure it's looking at the correct environment variables for finding the Path.
IMHO, the simplest setup for eclipse on windows these days is cygwin - it seems to have been updated more recently than mingw, and works better.
Go to http://www.cygwin.com/, download the installer, select the default directory of c:\cygwin. Select 'All users'.
When it offers a list of packages, select 'gcc', 'binutils' and 'make' under the 'devel' category.
Add c:\cygwin\bin to your windows environment PATH.
Make sure Eclipse knows where to find your gcc compiler. An easier way would be to use EasyEclipse until you are more comfortable with your dev env.
I needed to move from the MinGW gcc to the CygWin gcc - all the C++2011 works and others say it is a better option too. Download the CygWin binaries etc. and then open up Eclipse.
In project properties, C/C++ Build -> Environment and set the CYGWIN_HOME variable. This worked fine for me on Eclipse Kepler Windows 7 (64Bit)
I also put the cygwin bin directory at the front of my Windows PATH variable.
Full details here:
http://help.eclipse.org/indigo/index.jsp?topic=%2Forg.eclipse.cdt.doc.user%2Fconcepts%2Fcdt_o_home.htm
You can try installing wascana. It automatically set up GNU compiler for you on Windows.
I want to build a static library (*.LIB file) GNU libiconv on windows to be used with other libraries in Visual C++. Other libraries I'm using are built with "MultiThreaded DLL" (/MD) Runtime option. So, I need to build libiconv with the same option.
Problem is the libiconv uses GNU build system and I want to compile with /MD option. You can see the source structure of libiconv here:
http://cvs.savannah.gnu.org/viewvc/libiconv/?root=libiconv
Mr. Zlatkovic maintains the windows port of GNU libiconv for libxml2
you can see them here:
ftp://xmlsoft.org/libxml2/win32/iconv-1.9.2.win32.zip
I cannot use his port. I need to build from the latest version of libiconv-1.13. I wonder how this guy has ported it? Can some one please tell me how to build *.lib from this and compile it using MSVC?
EDIT:
Actually, I need to build few more gnu libraries with same settings. So, if I get solution for one library. I can do the same for all others.
I found PARK Youngho's How to Build libiconv with Microsoft Visual Studio over at The Code Project to be complete and clean (for VS2010 and GNU libiconv 1.14).
A little addition to your answer.
I had the same issue and found that the MinGW + MSYS solution was perfect.
Though, I needed to go a little further and generate also the .lib file in order to be able to link with the resulting dll.
This is what I found:
generate a .def file from the dll with dumpbin (a Visual Studio tool).
generate the .lib file from the .def with the lib program (Visual Studio tool too)
This allows you to specify some link flags if appropriate.
Everything detailed here (I'm not the author of this method):
http://wiki.videolan.org/GenerateLibFromDll
I also realized that this lib/dll couple can be linked with both MD and MDd libraries.
Hope that can help people that find this post, like it helped me.
-David
I'm the OP. MSYS is the exact thing what I was looking for.
Just install MinGW & MSYS which contains shell sh.exe & make.exewith which you can configure and generate a Makefile after that you can use make.exe to run it.
Its as simple as that.
compile them using MinGW using Msys for the environment if needed. MinGW's .a files are apparently, according to the mailing list, the same format as .lib files (just do a rename). You might want to check first to see if the iconv static library is included already in the MinGW download / filesystem.
Edit: it's in msys (C:\msys\1.0\lib), along with:
libiconv.a
libiconv.dll.a
libiconv.la
and additionally
libiconv-2.dll (in C:\msys\1.0\local\bin)
Edit: is it in here, the libiconv you need? these versions seem to have MSVC makefiles :) http://www.opensource.apple.com/source/libiconv/
I haven't done C in a long time. I'd like to compile this program, but I have no idea how to proceed. It seems like the makefile refers to GCC a lot and I've never used GCC.
I just want an executable that will run on windows.
You may need to install either cygwin or mingw, which are UNIX-like environments for Windows.
http://www.mingw.org/
http://www.cygwin.com/
When downloading/installing either cygwin or mingw, you will have the option of downloading and installing some optional features; you will need the following:
gcc (try version 2.x first, not 3.x)
binutils
GNU make (or gmake)
If it requires gcc and you want it to run on Windows, you could download Cygwin.
That's basically an emulator for GNU/Linux type stuff for Windows. It works with an emulation DLL.
http://www.cygwin.com/
In order to compile this program you need a C compiler. It does not have to be gcc, although you are already given a makefile set up to use gcc. The simplest thing for you to do would be the following:
Install cygwin
Open the cygwin command prompt
go into the directory where you have your makefile
type 'make'
That should compile your program
If you are not comfortable with using command line tools then you can download the free version of MS Visual Studio and import the source files into a new Visual Studio project. This way you would not need to install cygwin and use gcc, but you would need to know how to create projects and run programs in Visual Studio.
You almost certainly don't need all of cygwin to compile using gcc. There are plenty of standalone gcc clones for Windows, like gcw.
If it's reasonably portable C code (I haven't looked at it), then you may be able to just ignore the included Makefile and feed the source into whatever compiler you do want to use. What happens when you try that?
Dev-C++ provides a simple but nice IDE which uses the Mingw gcc compiler and provides Makefile support. Here are the steps I used to build the above code using Dev-C++ (i.e. this is a "how-to")
After downloading the source zip from NIST, I
downloaded and installed the Dev-C++ 5 beta 9 release
created a new empty project
added all the .c files from sts-2.0\src
Then under Project Options
added -lm in the Linker column under Parameters
added sts-2.0\include to the Include Directories in Directories
set the Executable and Object directories to the obj directory under the Build Options
and then hit OK to close the dialog. Go to Execute > Compile and let it whirl. A minute later, you can find the executable in the sts-2.0\obj directory.
First, there is little chance that a program with only makefiles will build with visual studio, if only because visual studio is not a good C compiler from a standard POV (the math functions in particular are very poorly supported on MS compilers). It may be possible, but it won't be easy, specially if you are not familiar with C. You should really stick to the makefiles instead of trying to import the code in your own IDE - this kind of scienfitic code is clearly meant to be compiled from the command line. It is a test suite, so trying things randomly is NOT a good idea.
You should use mingw + msys to install it: mingw will give you the compilers (gcc, etc...) and msys the shell for the make file to run correctly. Contrary to one other poster, I would advise you against using gcc 2 - I don't see any point in that. I routinely use gcc 3 (and even 4) on windows to build scientific code, it works well when the code is unix-like (which is the standard platform for this kind of code).