I'm trying to compile my project and I use the lib ncurse. And I've got some errors when compiler links files.
Here is my flags line in Makefile:
-W -Wall -Werror -Wextra -lncurses
I've included ncurses.h
Some layouts :
prompt$> dpkg -S curses.h
libslang2-dev:amd64: /usr/include/slcurses.h
libncurses5-dev: /usr/include/ncurses.h
libncurses5-dev: /usr/include/curses.h
prompt$> dpkg -L libncurses5-dev | grep .so
/usr/lib/x86_64-linux-gnu/libncurses.so
/usr/lib/x86_64-linux-gnu/libcurses.so
/usr/lib/x86_64-linux-gnu/libmenu.so
/usr/lib/x86_64-linux-gnu/libform.so
/usr/lib/x86_64-linux-gnu/libpanel.s
And here are my erros :
gcc -W -Wall -Werror -Wextra -I./Includes/. -lncurses -o Sources/NCurses/ncurses_init.o -c Sources/NCurses/ncurses_init.c
./Sources/NCurses/ncurses_init.o: In function `ncruses_destroy':
ncurses_init.c:(.text+0x5): undefined reference to `endwin'
./Sources/NCurses/ncurses_init.o: In function `ncurses_write_line':
ncurses_init.c:(.text+0xc5): undefined reference to `mvwprintw'
./Sources/NCurses/ncurses_init.o: In function `ncurses_init':
ncurses_init.c:(.text+0xee): undefined reference to `initscr'
collect2: error: ld returned 1 exit status
Thanks a lot
You need to change your makefile so that the -lncurses directive comes after your object code on the gcc command line, i.e. it needs to generate the command:
gcc -W -Wall -Werror -Wextra -I./Includes/. -o Sources/NCurses/ncurses_init.o -c Sources/NCurses/ncurses_init.c -lncurses
This is because object files and libraries are linked in order in a single pass.
In C++ , I fixed it just by linking the ncurses library .
Here is the command :
g++ main.cpp -lncurses
I got flags to correct order by using LDLIBS variable:
ifndef PKG_CONFIG
PKG_CONFIG=pkg-config
endif
CFLAGS+=-std=c99 -pedantic -Wall
LDLIBS=$(shell $(PKG_CONFIG) --libs ncurses)
man gcc | grep -A10 "\-l library"
-l library
Search the library named library when linking. (The second alternative with the library as a separate argument is only for POSIX
compliance and is not recommended.)
It makes a difference where in the command you write this option; the linker searches and processes libraries and object files
in the order they are specified. Thus, foo.o -lz bar.o searches
library z after file foo.o but
before bar.o. If bar.o refers to functions in z, those functions may not be loaded.
Related
we are trying to make a c++ shared object library to interface with a static fortran library (compiled with mpif90). There is one fortran wrapper file compiled with gfortran or mpif90 (both fail) and one c++ wrapper file compiled with g++
The compilation command is
g++ -std=c++11 -ftemplate-depth-256 -Wno-inline -fPIC -O3 -pthread -fopenmp -v -I /usr/lib/x86_64-linux-gnu/openmpi/include/ -I /opt/local/nextsim/modules/oasis/include -o /opt/local/nextsim/lib/liboasis.so.1.0 /opt/local/nextsim/objs/./oasis_cpp_interface.o /opt/local/nextsim/objs/./oasis_cpp_interface_ftn.o /docker_io/compile_oa3-mct/lib/libpsmile.MPI1.a /docker_io/compile_oa3-mct/lib/libmct.a /docker_io/compile_oa3-mct/lib/libmpeu.a /docker_io/compile_oa3-mct/lib/libscrip.a -fopenmp -Wl,-rpath,/usr/lib/x86_64-linux-gnu/openmpi/lib/ -L /usr/lib/x86_64-linux-gnu/openmpi/lib/ -lmpi_cxx -lmpi -ldl -lstdc++ -lpthread -L /docker_io/compile_oa3-mct/lib -Wl,-rpath,/usr/lib/x86_64-linux-gnu -L /usr/lib/x86_64-linux-gnu -lnetcdff -shared -Wl,-soname,liboasis.so.1
The error it gives is:
/usr/bin/x86_64-linux-gnu-ld: /docker_io/compile_oa3-mct/lib/libpsmile.MPI1.a(mod_oasis_auxiliary_routines.o): relocation R_X86_64_PC32 against symbol `__mod_oasis_data_MOD_mpi_comm_local' can not be used when making a shared object; recompile with -fPIC
/usr/bin/x86_64-linux-gnu-ld: final link failed: Bad value
As you can see we already compiled with -fPIC (as was the fortran library and the c++ objects). I also tried linking the fortran objects instead of the libraries, but they were also using some other static libraries which gave the same error.
Actually for some reason, our code compiles on one particular server, but not another, and not inside docker (ubuntu) so the problem is a little puzzling.
The -fPIC option is ineffective in your commandline:
g++ -std=c++11 -ftemplate-depth-256 -Wno-inline -fPIC -O3 -pthread -fopenmp -v \
-I /usr/lib/x86_64-linux-gnu/openmpi/include/ -I /opt/local/nextsim/modules/oasis/include \
-o /opt/local/nextsim/lib/liboasis.so.1.0 \
/opt/local/nextsim/objs/./oasis_cpp_interface.o \
/opt/local/nextsim/objs/./oasis_cpp_interface_ftn.o \
/docker_io/compile_oa3-mct/lib/libpsmile.MPI1.a \
/docker_io/compile_oa3-mct/lib/libmct.a \
/docker_io/compile_oa3-mct/lib/libmpeu.a \
/docker_io/compile_oa3-mct/lib/libscrip.a \
-fopenmp -Wl,-rpath,/usr/lib/x86_64-linux-gnu/openmpi/lib/ \
-L /usr/lib/x86_64-linux-gnu/openmpi/lib/ \
-lmpi_cxx -lmpi -ldl -lstdc++ -lpthread -L /docker_io/compile_oa3-mct/lib \
-Wl,-rpath,/usr/lib/x86_64-linux-gnu \
-L /usr/lib/x86_64-linux-gnu -lnetcdff \
-shared -Wl,-soname,liboasis.so.1
because -fPIC is a compilation option and this is a linkage command. No source files
are input. Compilation has already been done. The other compilation options in this commandline:
std=c++11 -ftemplate-depth-256 -Wno-inline -fopenmp
-I /usr/lib/x86_64-linux-gnu/openmpi/include/ -I /opt/local/nextsim/modules/oasis/include \
are also redundant.
The linker says that the object file libpsmile.MPI1.a(mod_oasis_auxiliary_routines.o),
i.e. member mod_oasis_auxiliary_routines.o of the archive libpsmile.MPI1.a, was not
compiled with -fPIC. You say that:
we already compiled with -fPIC (as was the fortran library and the c++ objects).
but it's more likely that -fPIC was not used in the compilation of
the object files in libpsmile.MPI1.a than that the linker is mistaken.
Recompile all the object files input to the linkage, including those within static libraries, ensuring that -fPIC is enabled. All object files that are linked into a shared library must be Position-Independent-Code.
I'm trying to experiment around in ncurses for the first time, but I'm having problems compiling my source code. As far as I can tell, ncurses is installed and in the proper directories.
My makefile is super simple:
.cpp :
g++ -Wall -g -o $* $*.cpp -std=c++11 -lncurses
and here's my output when I try to locate ncurses.h
$ locate ncurses.h
/usr/include/ncursesw/ncurses.h
and when I check to see if it's installed
$ dpkg -l | grep ncurses
ii libncurses5:amd64 5.9+20140118-1ubuntu1 amd64 shared libraries for terminal handling
ii libncursesw5:amd64 5.9+20140118-1ubuntu1 amd64 shared libraries for terminal handling (wide character support)
ii libncursesw5-dev:amd64 5.9+20140118-1ubuntu1 amd64 developer's libraries for ncursesw
ii mtr-tiny 0.85-2 amd64 Full screen ncurses traceroute tool
ii ncurses-base 5.9+20140118-1ubuntu1 all basic terminal type definitions
ii ncurses-bin 5.9+20140118-1ubuntu1 amd64 terminal-related programs and man pages
ii ncurses-term 5.9+20140118-1ubuntu1 all additional terminal type definitions
But g++ tells me this when I try to make
bankacct.cpp:18:29: fatal error: ncurses.h: No such file or directory
compilation terminated.
Unfortunately, I've not got root access and I need to be able to compile on this machine. What are my options?
I've tried including <ncursesw/ncurses.h> based on suggestions from other users, but now g++ is giving me this error:
$ make bankacct
g++ -Wall -g -o bankacct bankacct.cpp -std=c++11 -lncurses
/usr/bin/ld: cannot find -lncurses
and if I try removing -lncurses it gives me this:
$ make bankacct
g++ -Wall -g -o bankacct bankacct.cpp -std=c++11
/tmp/cc8rPQfK.o: In function `main':
bankacct.cpp:23: undefined reference to `initscr'
Now I've tried linking the libraries. Here's what I did:
$ locate libncurse
/lib/x86_64-linux-gnu/libncurses.so.5
/lib/x86_64-linux-gnu/libncurses.so.5.9
/lib/x86_64-linux-gnu/libncursesw.so.5
/lib/x86_64-linux-gnu/libncursesw.so.5.9
/usr/lib/x86_64-linux-gnu/libncurses++w.a
/usr/lib/x86_64-linux-gnu/libncursesw.a
/usr/lib/x86_64-linux-gnu/libncursesw.so
/usr/share/doc/libncurses5
/usr/share/doc/libncursesw5
/usr/share/doc/libncursesw5-dev
/var/lib/dpkg/info/libncurses5:amd64.list
/var/lib/dpkg/info/libncurses5:amd64.md5sums
/var/lib/dpkg/info/libncurses5:amd64.postinst
/var/lib/dpkg/info/libncurses5:amd64.postrm
/var/lib/dpkg/info/libncurses5:amd64.shlibs
/var/lib/dpkg/info/libncurses5:amd64.symbols
/var/lib/dpkg/info/libncursesw5-dev:amd64.list
/var/lib/dpkg/info/libncursesw5-dev:amd64.md5sums
/var/lib/dpkg/info/libncursesw5-dev:amd64.postinst
/var/lib/dpkg/info/libncursesw5:amd64.list
/var/lib/dpkg/info/libncursesw5:amd64.md5sums
/var/lib/dpkg/info/libncursesw5:amd64.postinst
/var/lib/dpkg/info/libncursesw5:amd64.postrm
/var/lib/dpkg/info/libncursesw5:amd64.shlibs
/var/lib/dpkg/info/libncursesw5:amd64.symbols
So then I tried two variations of my makefile:
g++ -Wall -g -L/usr/lib/x86_64-linux-gnu/ -o $* $*.cpp -std=c++11 -lncurses
and
g++ -Wall -g -L/lib/x86_64-linux-gnu/ -o $* $*.cpp -std=c++11 -lncurses
which still gave me the errors undefined reference to 'initscr' (without -lncurses) or /usr/bin/ld: cannot find -lncurses (with it)
-lncurses
tells the linker to look for a library called "ncurses.". You clearly indicate that's not what your library is called:
/usr/lib/x86_64-linux-gnu/libncursesw.a
You need
-lncursesw
You don't need to modify the source code to specify <ncursesw/ncurses.h> you can simply add
-I/usr/include/ncursesw
I'm trying to build some example c++ code that use boost library. I use this as reference example of static linking.
And everything is fine when I build with dynamic libs.
g++ -Wall -std=c++0x -O3 -Wfatal-errors -I/usr/include/boost/include -c -o src/main.o src/main.cpp
g++ -Wall -std=c++0x -O3 -Wfatal-errors -I/usr/include/boost/include -c -o src/ThreadExample.o src/ThreadExample.cpp
g++ -Wall -std=c++0x -O3 -Wfatal-errors -I/usr/include/boost/include -c -o src/Utils.o src/Utils.cpp
g++ src/main.o src/ThreadExample.o src/Utils.o -lboost_thread -lboost_filesystem -lboost_system -lboost_timer -o ThreadExampleBinary
But when I use static libs I get lots of undefined reference errors:
g++ -Wall -std=c++0x -O3 -Wfatal-errors -I/usr/include/boost/include -c -o src/main.o src/main.cpp
g++ -Wall -std=c++0x -O3 -Wfatal-errors -I/usr/include/boost/include -c -o src/ThreadExample.o src/ThreadExample.cpp
g++ -Wall -std=c++0x -O3 -Wfatal-errors -I/usr/include/boost/include -c -o src/Utils.o src/Utils.cpp
g++ -static src/main.o src/ThreadExample.o src/Utils.o -lboost_thread -lboost_filesystem -lboost_system -lboost_timer -o ThreadExampleBinary
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/libboost_timer.a(cpu_timer.o): In function `boost::timer::cpu_timer::start()':
(.text+0x7fd): undefined reference to `boost::chrono::steady_clock::now()'
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/libboost_timer.a(cpu_timer.o): In function `boost::timer::cpu_timer::stop()':
(.text+0x94c): undefined reference to `boost::chrono::steady_clock::now()'
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/libboost_timer.a(cpu_timer.o): In function `boost::timer::cpu_timer::elapsed() const':
(.text+0xa59): undefined reference to `boost::chrono::steady_clock::now()'
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/libboost_timer.a(cpu_timer.o): In function `boost::timer::cpu_timer::resume()':
(.text+0xb60): undefined reference to `boost::chrono::steady_clock::now()'
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/libboost_timer.a(cpu_timer.o): In function `boost::timer::auto_cpu_timer::auto_cpu_timer(std::ostream&, short)':
(.text+0xca5): undefined reference to `boost::chrono::steady_clock::now()'
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/libboost_timer.a(cpu_timer.o):(.text+0xd4e): more undefined references to `boost::chrono::steady_clock::now()' follow
collect2: error: ld returned 1 exit status
make: *** [ThreadExampleBinary] Error 1
Seems this can be fixed adding additional -lboost_chrono library.
But why it works in dinamic setting?
With static linking, you have to also statically link to any libraries depended on by the libraries you are linking to.
The difference is that shared libraries have an entry in the ELF header, called NEEDED that lists other shared libraries that are to be included when you link in this one.
You can see them with this command:
$ objdump -p /usr/lib/libboost_timer.so | grep NEEDED
NEEDED libboost_chrono.so.1.60.0
NEEDED libboost_system.so.1.60.0
NEEDED librt.so.1
NEEDED libstdc++.so.6
NEEDED libgcc_s.so.1
NEEDED libc.so.6
But for static libraries there is no such system, as they are simply collection of object files.
It is worth noting that the NEEDED entry in the shared objects are entirely optional, and if they are not available, then they will behave exactly like the static ones. But most shared libraries include them.
Many libraries use the pkg-config infrastructure to provide the full command line needed, but AFAIK boost is not one of them.
How to automate this process? Well, you do not. You just include what is needed and follow the linker errors to discover further needs.
You can find which static library includes a symbol with something like:
$ nm --print-file-name --defined-only --demangle /usr/lib/*.a 2> /dev/null | \
grep -q 'boost::chrono::steady_clock::now()'
/usr/lib/libboost_chrono.a:chrono.o:0000000000000090 T boost::chrono::steady_clock::now()
But why it works in dinamic setting?
Most of my make files have the following notes (from when I found the answer back when I needed it ... sorry, I don't know where I found it.)
Note - when a build using '-l' finds the .so version of that library (so - shared object) and the same .a archive is also there, g++ prefers the .so over the .a.
However, you can still achieve static link by fully specifying the path to .a.
Example:
$(CC) $(CC_FLAGS) $< /usr/local/lib/libboost_chrono.a -o $# ...
# ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Sometimes, archive code refers to symbols in yet another archive.
i.e. -lyyy_i686 uses some function from -lxxx_i686, and xxx was listed first in the build command. It is possible that a symbol might remain unresolved and the linker fails.
When this happens, try adding xxx a second time to the end of the archive list
from: -lxxx_i686 -lyyy_i686 -lrt -pthread
becomes -lxxx_i686 -lyyy_i686 -lrt -pthread -lxxx_i686
^^^^^^^^^_____________________________^^^^^^^^^^
The preceeding presumes only .a libraries are findable (no xxx.so)
Another alternative, you can command the linker to search an archive multiple times
-lyyy_i686 -lrt -pthread -(-lxxx_i686-)
tell gcc to link this library as many times as needed __^^__________^^
Again, only .a is findable
Finally, if you choose to link with the .so, note that this does not pull in the entire lib into the current build target. Instead, at runtime, the .so is loaded into memory, if it is not already there. This happens after the program starts. For most applications, this is considered a 'small' start-up performance hit as the program adjusts its memory map (automagically behind the scenes). I believe I once found that the app itself can control when to load the .so.
The use of .so pulls in the entire library to memory (if not already installed). Thus, there would not be any missing symbols, in my xxx vs yyy scenario above, the .so pulls all the symbols, whether used or not.
And once again, when trying to load xxx using "-lxxx_i686", the linker prefers to pull in libxxx_i686.so even when the libxxx_i686.a is in the same directory.
This is my first time trying to make a simple library. I worked in Ubuntu 12.04 with g++ 4.6.3. Here is the problem:
[[mylib.cpp]]
#include<sqlite3.h>
void Mylib::blahblah() {...}
void Mylib::evenmoreblah() {...}
...
[[mylib.h]]
#include <...>
class Mylib {
...
};
Then I made the lib by:
gcc -c -Wall -fpic mylib.cpp
gcc -shared -o libmylib.so mylib.o
I used the library in a single test.cpp which contains only the main(). I put libmylib.so in ./libdir, and compiled by using:
g++ -g test.cpp -o test -lpthread -L/usr/local/lib -lsqlite3 -L./libdir -lmylib
The error I got:
./libdir/libmylib.so: undefined reference to `sqlite3_close'
./libdir/libmylib.so: undefined reference to `sqlite3_exec'
./libdir/libmylib.so: undefined reference to `sqlite3_free'
./libdir/libmylib.so: undefined reference to `sqlite3_open'
You could link -lsqlite3 into your shared library with
gcc -shared mylib.o -o libmylib.so -lsqlite3
If you do that, you don't need to explicitly link -lsqlite3 to your program, but that won't harm.
and the order of linking arguments for your program is important:
g++ -Wall -g test.cpp -o mytest \
-L./libdir -lmylib -L/usr/local/lib -lsqlite3 -lpthread
it should go from higher-level libraries to lower-level (i.e. system) ones. And don't forget -Wall to get almost all warnings from the compiler, which is very useful.
Read the Program Library HowTo.
PS. Don't call your program test which is a shell builtin (and the standard /usr/bin/test). Use some other name.
If your library make references to sqlite3, you should link sqlite after linking your library :
g++ -g test.cpp -o test -lpthread -L/usr/local/lib -L./libdir -lmylib -lsqlite3
Otherwise ld won't find anything useful in libsqlite3 before linking your library and won't be able to find the requested symbols after that.
Since your library uses sqlite3, you need to add that AFTER your own library in the linker command. I think you could add it to the linking of your shared library too, but not certain.
The linker resolves libraries and their references in the order you list them, so the order is important.
I have a makefile which looks like this .
DEFINES=-std=c++0x
INCS_GTK=-I/usr/include/gtk-2.0 -I/usr/include/glib-2.0 -I/usr/include/atk-1.0 -I/usr/include/cairo -I/usr/include/gdk-pixbuf-2.0 -I/usr/include/gtk-2.0/gdk -I/usr/include/pango-1.0 -I/usr/lib/gtk-2.0/include -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I/usr/lib/x86_64-linux-gnu/gtk-2.0/include
INCS=-I/usr/include/freetype2 -I/usr/include/mysql -Iframeworks ${INCS_GTK}
LDLIBS=-lconfig++ -lcxcore -lcv -lGL -lGLU -lglut -lhighgui -lSDL -lftgl -lueye_api -lboost_filesystem -lboost_system -lann -lpthread -lflycapture -lglog -lmysqlpp -lmysqlclient -lunittest++
DEBUG=-g -pg
WARNINGS=-Wall -Wextra -pedantic -Wno-long-long #-O3 -Weffc++
BUILDDIR=build
BINDIR=dist
MAINCXX=${shell find -name '*.cxx'}
TARGETS=${MAINCXX:%.cxx=%}
CXXFLAGS=${DEBUG} ${WARNINGS} ${DEFINES} ${INCS}
LDFLAGS=${DEBUG} ${WARNINGS} ${DEFINES}
include IDEconfigs/Makefile/generic.mk
I want to add the following paths of static libraries to the makefile .
/usr/local/lib/libYARP_OS.a /usr/local/lib/libYARP_sig.a /usr/local/lib/libYARP_math.a /usr/local/lib/libYARP_dev.a /usr/local/lib/libYARP_name.a /usr/local/lib/libYARP_init.a
how do i go about doing this .
Lets consider your /usr/local/lib/libYARP_OS.a.
What you can do is, have -L/usr/local/lib/ in your makefile as one of the variables. And then you can have -lYARP_OS appended to the LDLIBS.
-L is for path to the lib and -l is the lib name here libYARP_OS.a will be passed as -lYARP_OS.
On the command line you would do something like: gcc -o main main.c -L/usr/local/lib/ -lYARP_OS. This should give you an idea.
You can either use an -L<path> flag to tell GCC about the location of any library, and then include it with -l<libname>. For example this would be
$ gcc -o main main.c -L/usr/local/lib/ -lYARP_SO
as noted by swair.
Alternatively, you can also supply the full path of the static library and compile directly, like
$ gcc -o main main.c /usr/local/lib/libYARP_OS.a
See 'Shared libraries and static libraries' for details.
In your specific case I would add them to the LDLIBS= line.
NB: Be careful about linking order, this is relevant when linking programs together. See 'Link order of libraries' for details. For example:
$ gcc -Wall calc.c -lm -o calc (correct order)
works
$ cc -Wall -lm calc.c -o calc (incorrect order)
main.o: In function `main':
main.o(.text+0xf): undefined reference to `sqrt'
Also see this similar question: How to link to a static library in C?
Append -lYARP_OS -lYARP_sig -lYARP_math -lYARP_dev -lYARP_name -lYARP_init to LDLIBS.
Warning: the linking order may matter.
Also, be sure that the linker knows that /usr/local/lib is a place where to look for libraries, otherwise instruct it with -L/usr/local/lib (you could add another makefile variable, e.g. LIBPATHS or something similar, to contain the libraries paths).
As a general synopsis, if you have a library libMyLib.a in folder /my/path, the gcc (or g++) can be invoked with the following parameters:
gcc -L/my/path -lMyLib [...]
-L is used to include paths where the linker will look for libraries
-l is used to link a library, which must be passed without the lib prefix and the extension
This question may be useful for a general understanding of libraries usage in C and C++: How to use Libraries
In Makefile , add like this
USER_LIBS = -lYARP_OS -lYARP_sig -lYARP_math -lYARP_dev -lYARP_name -lYARP_init
This will link the libraries you required