I'm working on a program in which I use PDCurses3.5 functions using i686-w64-mingw32-gcc.exe.
When I compile the program, I keep getting errors such as "undefined reference to 'COLS'", "undefined reference to 'lines'".
I have checked that <curses.h> header and the library package properly installed.
Here is my input line:
> i686-w64-mingw32-gcc.exe set.o read.o elements.o random.o
> -L../standard/test -lplotfit -lplotget -lgfortran -Wl,--subsystem,console -mwindows -o runtime/mingw/result -lm -static -lws2_32 -lpdcurses
And the first part of the error is:
../standard/bin/mingw/menu.o:menu.c:(.text+0xb): undefined reference to `COLS'
../standard/bin/mingw/menu.o:menu.c:(.text+0x16): undefined reference to `COLS'
../standard/bin/mingw/menu.o:menu.c:(.text+0x33): undefined reference to `LINES'
../standard/bin/mingw/menu.o:menu.c:(.text+0x47): undefined reference to `MOVE'
../standard/bin/mingw/menu.o:menu.c:(.text+0x74): undefined reference to `initscr'
...
It seems the program cannot refer to libpdcurses.a in its library file.
What am I doing wrong?
When you use -lpdcurses, the linker looks for libpdcurses.a in certain predefined locations, plus those specified via -L. But, by default, the library is built as pdcurses.a. To link it, you can directly specify its location; e.g.:
gcc -oprogname.exe progname.c pdcurses.a
or
gcc -oprog2.exe prog2.c /pdcurses/win32/pdcurses.a
Alternatively, you can rename the library to libpdcurses.a, and either copy it to a location in the existing search path, or use -L:
gcc -oprogname.exe progname.c -lpdcurses
or
gcc -oprog2.exe prog2.c -L/pdcurses/win32 -lpdcurses
Related
I am beginning to use the SDL library for the first time and I used the apt-get install to download it onto the windows subsystem (Ubuntu). When I make calls to functions from the SDL library and then run the makefile, I am presented with:
/home/display.c:13: undefined reference to `SDL_Init'
/home/display.c:14: undefined reference to `SDL_GetError'
/home/display.c:17: undefined reference to `SDL_CreateWindow'
/home/display.c:19: undefined reference to `SDL_GetError'
/home/display.c:22: undefined reference to `SDL_CreateRenderer'
/home/display.c:24: undefined reference to `SDL_GetError'
The makefile looks like:
gcc -Wall -Werror -Wextra -Wunused -std=gnu99 -g -O0 -Wpedantic -lpthread -lSDL2main -lSDL2
I believe the issue is in linking and that the compiler cannot find where SDL is. However, if this were the case, there should be an error stating that #include SDL2/SDL.h cannot be found. Could this be an installation issue or an issue with the way I link SDL in the makefile?
The order in which I was placing the flags was incorrect. The libraries should be after the .c and .h files.
I have a library which uses the log function from math.h. When I compile and package this library, I get no compilation errors, which is normal (I think).
Now when I try to use the library in an application, gcc gives me linker errors:
Compiling mytestlist using "mytestlist.o":
gcc mytestlist.o -I/student/cmpt332/pthreads -I. -std=c99 -Wall -pedantic -L. -L/student/cmpt332/pthreads/lib/linuxx86_64/ -llist -o mytestlist
./liblist.a(list_adders.o): In function `NodeCreate':
list_adders.c:(.text+0x343): undefined reference to `log'
./liblist.a(list_adders.o): In function `ListCreate':
list_adders.c:(.text+0x62f): undefined reference to `log'
./liblist.a(list_adders.o): In function `ListFree':
list_adders.c:(.text+0xdcc): undefined reference to `log'
list_adders.c:(.text+0xe55): undefined reference to `log'
list_adders.c:(.text+0xefb): undefined reference to `log'
./liblist.a(list_adders.o):list_adders.c:(.text+0xf96): more undefined references to `log' follow
collect2: error: ld returned 1 exit status
Makefile:47: recipe for target 'mytestlist' failed
make: *** [mytestlist] Error 1
Why is this happening? The only solution that works is that I have to supply the -lm option to gcc when I compile the program that uses the library (even though the program itself makes no use of math.h), however I find this cumbersome to do.
I've also tried supplying the -lm option when compiling the library, but when the application is compiled using the library, I get the same linker errors.
Is there a way to compile the library with math.h without having to supply -lm to other programs that make use of the library?
In case you're wondering, I compile each object that makes up the library using:
gcc -std=c99 -Wall -pedantic -static -I. -c list_adders.c -o list_something.o -lm
And the library is packaged using:
ar cvfr liblist.a list_something.o ...
In your gcc -c command, the -lm isn't doing anything. It's a linker option, and -c means "don't link".
The proper place to put -lm is in fact after the -llist whenever you use it. That's how static library dependencies are done. Put it in the documentation for liblist.
If you want something fancier, there's pkg-config. With the appropriate configuration files, pkg-config --static --libs liblist will output -llist -lm.
(I am on Ubuntu) I am trying to run the PortAudio examples, but getting many errors (mentioned below). I have placed the header file portaudio.h in the directory of the program. I have no idea about it. I think it is linker error. Please help!
/tmp/cc5EbTlT.o: In function main':
paex_record.c:(.text+0x37e): undefined reference toPa_Initialize'
paex_record.c:(.text+0x397): undefined reference to Pa_GetDefaultInputDevice'
paex_record.c:(.text+0x3de): undefined reference toPa_GetDeviceInfo'
paex_record.c:(.text+0x436): undefined reference to Pa_OpenStream'
paex_record.c:(.text+0x45a): undefined reference toPa_StartStream'
paex_record.c:(.text+0x493): undefined reference to Pa_Sleep'
paex_record.c:(.text+0x4c2): undefined reference toPa_IsStreamActive'
paex_record.c:(.text+0x4eb): undefined reference to Pa_CloseStream'
paex_record.c:(.text+0x5fa): undefined reference toPa_GetDefaultOutputDevice'
paex_record.c:(.text+0x641): undefined reference to Pa_GetDeviceInfo'
paex_record.c:(.text+0x6b2): undefined reference toPa_OpenStream'
paex_record.c:(.text+0x6e3): undefined reference to Pa_StartStream'
paex_record.c:(.text+0x71c): undefined reference toPa_Sleep'
paex_record.c:(.text+0x728): undefined reference to Pa_IsStreamActive'
paex_record.c:(.text+0x74e): undefined reference toPa_CloseStream'
paex_record.c:(.text+0x77d): undefined reference to Pa_Terminate'
paex_record.c:(.text+0x7e5): undefined reference toPa_GetErrorText'
collect2: error: ld returned 1 exit status
Assuming you are compiling using gcc and you have a single C file foo.c, the compiler command would be
gcc -o foo foo.c -lrt -lasound -ljack -lpthread -lportaudio
The -l parameters are there to link the required libraries to your program, e.g. -lrt will link librt.a. The order does matter.
I got the required libraries from here: http://www.portaudio.com/docs/v19-doxydocs/compile_linux.html#comp_linux3. Don't know if they are correct. At least you need -lportaudio, obviously.
If the libraries are not found, you have to provide gcc a path, e.g.
gcc -L/usr/lib -o foo foo.c -lrt -lasound -ljack -lpthread -lportaudio
Regarding the header, you don't actually need to copy it into your program's directory. You'd rather include it as
#include <portaudio.h>
and add its directory to the include search path:
gcc -I/usr/include -L/usr/lib -o foo foo.c -lrt -lasound -ljack -lpthread -lportaudio
Of course, all this is better done in a Makefile.
I am trying to compile a C program, while linking the APR library.
I am getting the following error message:
cc -g -Wall -pthread -I/usr/local/apr/include/apr-1 -I/usr/local/apr/include/apr-util-1 -L/usr/local/apr/lib -L .aprutil-1 -L .apr-1 devpkg.c bstrlib.o db.o shell.o commands.o -o devpkg
/tmp/cczC53x5.o: In function `main':
/home/yotam/Dropbox/Development/C/devpkg/devpkg.c:14: undefined reference to `apr_pool_initialize'
/home/yotam/Dropbox/Development/C/devpkg/devpkg.c:15: undefined reference to `apr_pool_create_ex'
/home/yotam/Dropbox/Development/C/devpkg/devpkg.c:29: undefined reference to `apr_getopt_init'
/home/yotam/Dropbox/Development/C/devpkg/devpkg.c:31: undefined reference to `apr_getopt'
db.o: In function `DB_init':
/home/yotam/Development/C/devpkg/db.c:89: undefined reference to `apr_pool_initialize'
/home/yotam/Development/C/devpkg/db.c:90: undefined reference to `apr_pool_create_ex'
/home/yotam/Development/C/devpkg/db.c:93: undefined reference to `apr_dir_make_recursive'
/home/yotam/Development/C/devpkg/db.c:105: undefined reference to `apr_pool_destroy'
/home/yotam/Development/C/devpkg/db.c:109: undefined reference to `apr_pool_destroy'
shell.o: In function `Shell_exec':
/home/yotam/Development/C/devpkg/shell.c:16: undefined reference to `apr_pool_create_ex'
/home/yotam/Development/C/devpkg/shell.c:38: undefined reference to `apr_pool_destroy'
/home/yotam/Development/C/devpkg/shell.c:44: undefined reference to `apr_pool_destroy'
shell.o: In function `Shell_run':
/home/yotam/Development/C/devpkg/shell.c:55: undefined reference to `apr_procattr_create'
/home/yotam/Development/C/devpkg/shell.c:58: undefined reference to `apr_procattr_io_set'
/home/yotam/Development/C/devpkg/shell.c:62: undefined reference to `apr_procattr_dir_set'
/home/yotam/Development/C/devpkg/shell.c:65: undefined reference to `apr_procattr_cmdtype_set'
/home/yotam/Development/C/devpkg/shell.c:68: undefined reference to `apr_proc_create'
/home/yotam/Development/C/devpkg/shell.c:71: undefined reference to `apr_proc_wait'
commands.o: In function `Command_fetch':
/home/yotam/Development/C/devpkg/commands.c:44: undefined reference to `apr_uri_parse'
/home/yotam/Development/C/devpkg/commands.c:48: undefined reference to `apr_fnmatch'
/home/yotam/Development/C/devpkg/commands.c:51: undefined reference to `apr_fnmatch'
/home/yotam/Development/C/devpkg/commands.c:70: undefined reference to `apr_fnmatch'
/home/yotam/Development/C/devpkg/commands.c:78: undefined reference to `apr_dir_make_recursive'
/home/yotam/Development/C/devpkg/commands.c:84: undefined reference to `apr_fnmatch'
/home/yotam/Development/C/devpkg/commands.c:90: undefined reference to `apr_dir_make_recursive'
collect2: error: ld returned 1 exit status
make: *** [devpkg] Error 1
Here is my makefile, it should be able to compile on different computers, where the PREFIX variable is the location relative to the computer.
(this program in essence should one day be portable to any OS. for now I would just like to be able to compile it successfully)
PREFIX?=/usr/local
LDFLAGS= -L${PREFIX}/apr/lib -L .aprutil-1 -L .apr-1
CFLAGS=-g -Wall -pthread -I${PREFIX}/apr/include/apr-1 -I${PREFIX}/apr/include/apr-util-1
all: devpkg
devpkg: bstrlib.o db.o shell.o commands.o
install: all \
install -d $(DESTDIR)/$(PREFIX)/bin/ \
install devpkg $(DESTDIR)/$(PREFIX)/bin/
clean:
rm -f *.o \
rm -f devpkg \
rm -rf *.dSYM
I've gone and searched for it myself in the folders and this is what I got:
yotam#yotam-HP-ProBook-450://usr$ grep -r apr_pool_initialize .
./local/apr/include/apr-1/apr_pools.h:APR_DECLARE(apr_status_t) apr_pool_initialize(void);
Binary file ./local/apr/lib/libapr-1.so.0.4.6 matches
Binary file ./local/apr/lib/libapr-1.a matches
Binary file ./local/apr/lib/libapr-1.so.0.5.1 matches
Binary file ./local/apr/lib/libapr-1.so.0.4.5 matches
./local/apr/lib/apr.exp:apr_pool_initialize
After the reaserch I did, I clearly understand that this is a linker problem. but I wasn't able to find the command to do the trick.
Thanks in advance.
Looks like you're missing the link option that tells cc which library to link with. I'm not sure what .aprutil-1 and .apr-1 are in your LDFLAGS macro, since you specify them with -L, I will assume they are directories.
However, if you change your line to add the -l option to specify the library, it should get you closer.
EDIT: Because the linker is a single pass tool, all the libraries need to be listed after the objects, so the symbols will not be optimized away. LDLIBS is a typical name for the macro where libraries are specified, and you can tack them on to the end of the compile/link command and it should work.
LDFLAGS= -L${PREFIX}/apr/lib -L .aprutil-1 -L .apr-1
LDLIBS= -lapr-1 -laprutil-1
The last two args tell the linker which library names (prepended with lib and appended with .a) to use. The -L option specifies additional directories to search for libraries, it doesn't actually include anything.
Alternatively, you can also set LD_LIBRARY_PATH to point to your library directories.
You can consult this site (among others) as a reference, if you need more help debugging.
Try replacing LDFLAGS with LDLIBS, as in:
LDLIBS=-L${PREFIX}/apr/lib -lapr-1 -pthread -laprutil-1
instead of:
LDFLAGS=-L${PREFIX}/apr/lib -lapr-1 -pthread -laprutil-1
This is because the LDFLAGS variable is meant for non-library options for the linker, whereas in this case you are using libraries.
I am trying to use Curl in C.
I visited Curl official page, and copied sample source code.
below is the link:
http://curl.haxx.se/libcurl/c/sepheaders.html
when I run this code with command "gcc test.c",
the console shows message like below.
/tmp/cc1vsivQ.o: In function `main':
test.c:(.text+0xe1): undefined reference to `curl_global_init'
test.c:(.text+0xe6): undefined reference to `curl_easy_init'
test.c:(.text+0x10c): undefined reference to `curl_easy_setopt'
test.c:(.text+0x12e): undefined reference to `curl_easy_setopt'
test.c:(.text+0x150): undefined reference to `curl_easy_setopt'
test.c:(.text+0x17e): undefined reference to `curl_easy_cleanup'
test.c:(.text+0x1b3): undefined reference to `curl_easy_cleanup'
test.c:(.text+0x1db): undefined reference to `curl_easy_setopt'
test.c:(.text+0x1e7): undefined reference to `curl_easy_perform'
test.c:(.text+0x1ff): undefined reference to `curl_easy_cleanup'
I do not know how to solve this.
You don't link with the library.
When using an external library you must link with it:
$ gcc test.c -lcurl
The last option tells GCC to link (-l) with the library curl.
In addition to Joachim Pileborg's answer, it is useful to remember that gcc/g++ linking is sensitive to order and that your linked libraries must follow the things that depend upon them.
$ gcc -lcurl test.c
will fail, missing the same symbols as before. I mention this because I came to this page for forgetting this fact.
I have the same problem, but i use g++ with a make file.
This is a linker issue.
You need to add option -lcurl on the compiler and on the linker.
In my case on the make file:
CC ?= gcc
CXX ?= g++
CXXFLAGS += -I ../src/ -I ./ -DLINUX -lcurl <- compile option
LDFLAGS += -lrt -lpthread -lcurl <- linker option
Gerard
Depending how bad things are you might need an -L/somewhere in LDFLAGS to let the linker know where the libraries are. ldconfig is supposed to pick them up and find them on every boot but on a new machine it can take a little prodding, like adding a directory to your /etc/ld.so.conf.