In order to try out FLTK, I have the following file structure:
project
|--main.cc
|--include
| |--FL
| | |--all FLTK header files
|--lib
| |--libfltk.a
| |--other fltk libraries
With the following content in main.cc:
#include <FL/Fl.H>
#include <FL/Fl_Box.H>
#include <FL/Fl_Window.H>
int main()
{
Fl_Window window(200, 200, "Window title");
Fl_Box box(0,0,200,200,"Hello, World!");
window.show();
return Fl::run();
}
Now when I run:
g++ -std=c++11 -c -o main.o main.cc -I include
g++ -std=c++11 -o main.exe main.o -L lib -lfltk
I get a whole bunch of errors after the second call to g++:
lib/libfltk.a(Fl.o):Fl.cxx:(.text$_ZL13image_to_iconPK12Fl_RGB_Imagebii+0xf3): undefined reference to `CreateDIBSection#24'
lib/libfltk.a(Fl.o):Fl.cxx:(.text$_ZL13image_to_iconPK12Fl_RGB_Imagebii+0x1cf): undefined reference to `DeleteObject#4'
lib/libfltk.a(Fl.o):Fl.cxx:(.text$_ZL13image_to_iconPK12Fl_RGB_Imagebii+0x258): undefined reference to `CreateBitmap#20'
lib/libfltk.a(Fl.o):Fl.cxx:(.text$_ZL13image_to_iconPK12Fl_RGB_Imagebii+0x2a6): undefined reference to `DeleteObject#4'
lib/libfltk.a(Fl.o):Fl.cxx:(.text$_ZL13image_to_iconPK12Fl_RGB_Imagebii+0x2b1): undefined reference to `DeleteObject#4'
lib/libfltk.a(Fl.o):Fl.cxx:(.text$__tcf_1+0x5b): undefined reference to `OleUninitialize#0'
lib/libfltk.a(Fl.o):Fl.cxx:(.text$__tcf_1+0x83): undefined reference to `RestoreDC#8'
etc ...
The result is the same when I try to link the other FLTK libraries. Can anyone help me with that?
I use gcc from Windows, with MingW.
To solve this sort of problems is necessary to take help from fltk-config script. Therefore, it is enought to add line fltk-config --ldflags to compiler to avoid linker errors. Be sure to use "`" symbol around this command since this is the script and its should be executed.
Related
I'm just starting to learn how to work with zeromq libraries and using them in different C++ projects.
The sample code that I wrote (actually copied from there tutorials)is this:
// file: main.cpp
// Hello World client in C++
// Connects REQ socket to tcp://localhost:5555
// Sends "Hello" to server, expects "World" back
//
#include <zmq.hpp>
#include <string>
#include <iostream>
int main ()
{
// Prepare our context and socket
zmq::context_t context (1);
zmq::socket_t socket (context, ZMQ_REQ);
std::cout << "Connecting to hello world server…" << std::endl;
socket.connect ("tcp://localhost:5555");
// Do 10 requests, waiting each time for a response
for (int request_nbr = 0; request_nbr != 10; request_nbr++) {
zmq::message_t request (5);
memcpy (request.data (), "Hello", 5);
std::cout << "Sending Hello " << request_nbr << "…" << std::endl;
socket.send (request);
// Get the reply.
zmq::message_t reply;
socket.recv (&reply);
std::cout << "Received World " << request_nbr << std::endl;
}
return 0;
}
and by building the output of this file with the command below:
g++ main.cpp -o test -lzmq
the file will be generated with no problem.
The problem that I have is that I want to build the file using CMake.Thus, I've written a CMakeLists.txt file as below:
cmake_minimum_required(VERSION 3.6)
project(test2)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -lzmq")
set(SOURCE_FILES main.cpp)
add_executable(test2 ${SOURCE_FILES})
The part that I thought will be enough to build the program is -lzmq but even with that piece included, I get the following error messages:
CMakeFiles/test2.dir/main.cpp.o: In function `zmq::error_t::error_t()':
/usr/include/zmq.hpp:62: undefined reference to `zmq_errno'
CMakeFiles/test2.dir/main.cpp.o: In function `zmq::error_t::what() const':
/usr/include/zmq.hpp:66: undefined reference to `zmq_strerror'
CMakeFiles/test2.dir/main.cpp.o: In function `zmq::message_t::message_t()':
/usr/include/zmq.hpp:107: undefined reference to `zmq_msg_init'
CMakeFiles/test2.dir/main.cpp.o: In function `zmq::message_t::message_t(unsigned long)':
/usr/include/zmq.hpp:114: undefined reference to `zmq_msg_init_size'
CMakeFiles/test2.dir/main.cpp.o: In function `zmq::message_t::~message_t()':
/usr/include/zmq.hpp:129: undefined reference to `zmq_msg_close'
CMakeFiles/test2.dir/main.cpp.o: In function `zmq::message_t::data()':
/usr/include/zmq.hpp:180: undefined reference to `zmq_msg_data'
CMakeFiles/test2.dir/main.cpp.o: In function `zmq::context_t::context_t(int)':
/usr/include/zmq.hpp:204: undefined reference to `zmq_init'
CMakeFiles/test2.dir/main.cpp.o: In function `zmq::context_t::~context_t()':
/usr/include/zmq.hpp:225: undefined reference to `zmq_term'
CMakeFiles/test2.dir/main.cpp.o: In function `zmq::socket_t::socket_t(zmq::context_t&, int)':
/usr/include/zmq.hpp:251: undefined reference to `zmq_socket'
CMakeFiles/test2.dir/main.cpp.o: In function `zmq::socket_t::close()':
/usr/include/zmq.hpp:283: undefined reference to `zmq_close'
CMakeFiles/test2.dir/main.cpp.o: In function `zmq::socket_t::connect(char const*)':
/usr/include/zmq.hpp:314: undefined reference to `zmq_connect'
CMakeFiles/test2.dir/main.cpp.o: In function `zmq::socket_t::send(zmq::message_t&, int)':
/usr/include/zmq.hpp:321: undefined reference to `zmq_send'
/usr/include/zmq.hpp:324: undefined reference to `zmq_errno'
CMakeFiles/test2.dir/main.cpp.o: In function `zmq::socket_t::recv(zmq::message_t*, int)':
/usr/include/zmq.hpp:331: undefined reference to `zmq_recv'
/usr/include/zmq.hpp:334: undefined reference to `zmq_errno'
Should I set another kind of variable in the CMake file or have I installed the library in a wrong directory? or is there anything else that I should have mentioned?
and The system witch I'm working on is Ubuntu 14.04
CMake doesn't include direct support for 0mq and 0mq doesn't include direct support for CMake. But, 0mq does support pkg-config and we can use this to help us. Since you mentioned that you're on Ubuntu 14.04, make sure you've done sudo apt-get install libzmq3-dev to install the 0mq libraries, headers, and the pkg-config .pc file.
Then use the following CMakeLists.txt which I've modified from your version above. (I've commented all my changes inline.)
## i have cmake 3.5
cmake_minimum_required(VERSION 3.5)
project(test2)
## use this to globally use C++11 with in our project
set(CMAKE_CXX_STANDARD 11)
## load in pkg-config support
find_package(PkgConfig)
## use pkg-config to get hints for 0mq locations
pkg_check_modules(PC_ZeroMQ QUIET zmq)
## use the hint from above to find where 'zmq.hpp' is located
find_path(ZeroMQ_INCLUDE_DIR
NAMES zmq.hpp
PATHS ${PC_ZeroMQ_INCLUDE_DIRS}
)
## use the hint from above to find the location of libzmq
find_library(ZeroMQ_LIBRARY
NAMES zmq
PATHS ${PC_ZeroMQ_LIBRARY_DIRS}
)
set(SOURCE_FILES main.cpp)
add_executable(test2 ${SOURCE_FILES})
## add the include directory to our compile directives
target_include_directories(test2 PUBLIC ${ZeroMQ_INCLUDE_DIR})
## at the 0mq library to our link directive
target_link_libraries(test2 PUBLIC ${ZeroMQ_LIBRARY})
Now you can make your project.
❯ make
[ 50%] Building CXX object CMakeFiles/test2.dir/main.cpp.o
[100%] Linking CXX executable test2
[100%] Built target test2
If you want to see what's happening under the hood, do a verbose make.
❯ make VERBOSE=1
/usr/bin/cmake -H/home/nega/foo -B/home/nega/foo/build --check-build-system CMakeFiles/Makefile.cmake 0
/usr/bin/cmake -E cmake_progress_start /home/nega/foo/build/CMakeFiles /home/nega/foo/build/CMakeFiles/progress.marks
make -f CMakeFiles/Makefile2 all
make[1]: Entering directory '/home/nega/foo/build'
make -f CMakeFiles/test2.dir/build.make CMakeFiles/test2.dir/depend
make[2]: Entering directory '/home/nega/foo/build'
cd /home/nega/foo/build && /usr/bin/cmake -E cmake_depends "Unix Makefiles" /home/nega/foo /home/nega/foo /home/nega/foo/build /home/nega/foo/build /home/nega/foo/build/CMakeFiles/test2.dir/DependInfo.cmake --color=
make[2]: Leaving directory '/home/nega/foo/build'
make -f CMakeFiles/test2.dir/build.make CMakeFiles/test2.dir/build
make[2]: Entering directory '/home/nega/foo/build'
[ 50%] Building CXX object CMakeFiles/test2.dir/main.cpp.o
/usr/bin/c++ -std=gnu++11 -o CMakeFiles/test2.dir/main.cpp.o -c /home/nega/foo/main.cpp
[100%] Linking CXX executable test2
/usr/bin/cmake -E cmake_link_script CMakeFiles/test2.dir/link.txt --verbose=1
/usr/bin/c++ CMakeFiles/test2.dir/main.cpp.o -o test2 /usr/lib/x86_64-linux-gnu/libzmq.so
make[2]: Leaving directory '/home/nega/foo/build'
[100%] Built target test2
make[1]: Leaving directory '/home/nega/foo/build'
/usr/bin/cmake -E cmake_progress_start /home/nega/foo/build/CMakeFiles 0
If you look at the compile line, you'll notice that
C++11 support was added (with the -std=gnu++11 flag)
There's no -I/path/to/zmq flag. That's because Ubuntu dumps zmq.hpp in to /usr/include and CMake is smart enough to know that is a default path, so it does nothing
If you look at the link line, you'll notice that libzmq.so has been included via it's full path. Some people don't like that (myself included) and prefer -L/lib/dir -lmylib instead. Using the full path is "the CMake way", and you'll actually come to appreciate it as you grow with CMake and use it for larger and more complicated projects (you still might not like it though.)
Also note, that since you're on Ubuntu we could have cheated and used dpkg -L libzmq3-dev to find the locations of the files we're interested in then added them to your original CMAKE_CXX_FLAGS line, but that's cheating and more importantly, not portable.
A cmake config file has been added to libzmq github repository Jan 7, 2017 here.
This is not included in the latest release (4.2.1) yet, but I belive it should be in the next release.
I have installed the head version using cmake and then installed cppzmq, which uses find_package(ZeroMQ REQUIRED) to locate libzmq. All worked like a charm.
EDIT: The cmake config file is included in release 4.2.2 here. Then it was moved to directory builds/cmake at release 4.2.4. I didn't test it again but find_package(ZeroMQ REQUIRED) should just work since ibzmq 4.2.2.
This works as well
cmake_minimum_required(VERSION 3.6)
project(test)
add_executable(c main.cpp)
target_link_libraries(c zmq)
When i compile with the following command:
g++ -fPIC -o obj/buffer.o buffer.cpp
I get the following error:
/usr/lib/gcc/x86_64-linux-gnu/4.6.1/../../../x86_64-linux-gnu/crt1.o:
In function _start': (.text+0x20): undefined reference tomain'
I am thought with the -fPIC flag, I didn't need a main function. I get this error with all of the cpp files. I do have a main.cpp that has the shared library functions in it. You can get the source code at the following:
git clone https://github.com/nterry/39DLL-4-Linux.git
Any ideas? I know that I can use the ld binary to put all of the o files in the an so once they're done, I just need help in building them all into shareable .o files
I think that I answered my question. I added a -c to the command and it seems to have worked. Here is the command I used:
g++ -fPIC -c -o obj/list.o list.cpp
That is one of several cpp files, and all seemed to work.
I am new to g++ and lapack, and attempting to use them. I encountered a problem when I tried to compile the following naive code
#include <lapackpp.h>
int main()
{
LaGenMatDouble A;
return 0;
}
If I run the command
$g++ -L/usr/local/lib -llapackpp test2.cpp
where test2.cpp is the name of the cpp file, the terminal would give an error:
test2.cpp:1:22: fatal error: lapackpp.h: No such file or directory
But if I run the command:
$g++ -I/usr/local/include/lapackpp -L/usr/local/lib -llapackpp test2.cpp
the terminal would give an error:
/tmp/ccUi11DG.o: In function `main':
test2.cpp:(.text+0x12): undefined reference to `LaGenMatDouble::LaGenMatDouble()'
test2.cpp:(.text+0x23): undefined reference to `LaGenMatDouble::~LaGenMatDouble()'
collect2: ld returned 1 exit status
BTW, if I run the command
$pkg-config lapackpp --libs
the result is
-L/usr/local/lib -llapackpp
Could you please help me solve this? Thanks in advance!
Lapack requires fortran libraries, so that's where the -lgfortran comes from. Moreover, it appears the exact way to provide that library for the compiler depends on the Linux distriburion. From the documentation:
Requirements
This package requires the packages "blas", "lapack" (without the "++"), and a Fortran compiler. On most Linuxes these are available as pre-compiled binaries under the name "blas" and "lapack". For SuSE 10.x, the Fortran compiler is available as package "gfortran". For SuSE 9.x, the Fortran compiler is available as package "gcc-g77".
Not sure why pkg-config lapackpp --libs does not list -lgfortran
The -I/usr/local/include/lapackpp specifes the lapackpp-related header files. Without it the compiler cannot find lapackpp.h when you try to include it (#include <lapackpp.h>) -- see the compiler error in your question
I finally solved the problem but would still wonder why it has to be so.
The only command that can link cpp file to lapackpp library is:
g++ foo.cpp -o foo -lgfortran -llapackpp -I/usr/local/include/lapackpp
It would not work without -lgfortran, or with -I/usr/local/include/lapackpp replaced by -L/usr/local/lib.
Does anyone have an answer?
My code is as simple as this:
#include <mpi.h>
int main(int argc, char**args) {
MPI_Init(&argc, &args);
int mpiSize;
int mpiRank;
MPI_Comm_size(MPI_COMM_WORLD, &mpiSize);
MPI_Comm_rank(MPI_COMM_WORLD, &mpiRank);
MPI_Finalize();
}
I first compile it to object file:
g++ -c src/mpitest.cpp -o src/mpitest.o
Then I can easily use mpicxx:
mpicxx src/mpitest.o -o mpi
But I want to use g++ instead, because It's easier for automake, so I tried:
mpicxx src/mpitest.o -o mpi -show
It prints out:
g++ src/mpitest.o -o mpi -I/usr/local/include -L/usr/local/lib -L/usr/local/lib -lmpichcxx -lmpich -lopa -lpthread -lrt
And yes, that command actually does the same thing successfully. However, If I tried to change it to (I just change the object file and output to the end):
g++ -I/usr/local/include -L/usr/local/lib -L/usr/local/lib -lmpichcxx -lmpich -lopa -lpthread -lrt src/mpitest.o -o mpi
Which is what automake does when it adds LDFLAGS, the g++ start complaining...
src/mpitest.o: In function `main':
..src/mpitest.cpp:5: undefined reference to `MPI_Init'
../src/mpitest.cpp:8: undefined reference to `MPI_Comm_size'
../src/mpitest.cpp:9: undefined reference to `MPI_Comm_rank'
../src/mpitest.cpp:10: undefined reference to `MPI_Finalize'
collect2: ld returned 1 exit status
What happens with g++ ? I couldn't figure out. Please enlighten me. Why the order here matter at all ? What is the proper way to do what I want from the beginning ?
Thanks a lot
p/s : g++ --version
g++ (Ubuntu 4.4.3-4ubuntu5) 4.4.3
mpi is mvapich2
I didn't really remember, maybe since version 4, library to link with -l must be passed after all source and object files.
Unfortunately I cannot post all of the source code here. I can describe the structure though. All header files have #ifndef/#define/#endif guards. The structure is as follows:
node.h - included by tree.h
tree.h - included by tree.cpp and main.cpp
tree.cpp
main.cpp
In node.h in the global namespace, I declare the following free standing function:
bool char_sort_func(Path first, Path second)
{
return (first->label() < second->label());
}
(Note: as shown bellow, a Path is just a shared_ptr) When I try to build, I get a multiple definition error saying that the function is present in both tree.o and main.o:
> make
g++ -c -g -Wall main.cpp -I /usr/include
g++ -c -g -Wall tree.cpp -I /usr/include
g++ -Wall -o tool tree.o main.o -L /usr/lib -l boost_program_options
main.o: In function `char_sort_func(boost::shared_ptr<Edge>, boost::shared_ptr<Edge>)':
node.h:70: multiple definition of `char_sort_func(boost::shared_ptr<Edge>, boost::shared_ptr<Edge>)'
tree.o:node.h:70: first defined here
collect2: ld returned 1 exit status
make: *** [all] Error 1
I tried searching all of the source files to see if that was true, however, I don't see it in any wrong places:
> grep char_sort_func *
Binary file main.o matches
node.h:bool char_sort_func(Path first, Path second)
node.h: std::sort(edges_.begin(), edges_.end(), char_sort_func);
Binary file trie.o matches
Sure enough though, it is in the binary files. How can I restructure my code to prevent this linking issue?
This will happen if you declare normal functions in a .h file, because they will be generated in every file that #includes it. Perhaps you meant to declare it inline or static?