I use Geany for C programming. When I try to build the file it gives me
error:undefined reference to sqrt.
Compile: gcc -Wall -c "%f"
Build: gcc -Wall -o "%e" "%f"
Execute: ./%e
I tried to add -lm to the build command but then it gives me
gcc error:no such file or directory.Compilation Failed.
The compiler and linker options with arguments must be separate, you can't compile them like you do.
Make them separate, like e.g.
gcc -Wall -o "%e" "%f" -lm
Related
I am using Linux mint 16. I had a code that I change it a bit.
I use two following commands in terminal in order to run the code. The problem is that it does not give me any error but the changes are not applied, which means it runs the previous version of code.
gcc -std=c99 -c Code.c -o Code.o
./Code
gcc -std=c99 -c Code.c -o Code.o will put the compiled object file in Code.o, not ./Code as you expect it to be..
Also, -c tells do not run the linker. So effectively you end up with an object file which cannot be run.
gcc -std=c99 Code.c -o Code will produce what you need.
For a complete list of gcc flags either use man gcc or see http://linux.die.net/man/1/gcc
Try
gcc -std=c99 -c Code.c -o Code
./Code
I am coding up some .c files using Geany, and I am interested in compiling using the c99 standard.
I see that I can set build commands and I assume this is where I need to be, but I can't seem to get the syntax correct. Here are commands that I've tried in the Compile tab, but none seem to work;
gcc -std=c99 -Wall -c "%f"
gcc -Wall -c -std=c99 "%f"
gcc -Wall -std=c99 -c "%f"
Any help is appreciated!
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.
I'm new to makefiles, so I apologize in advance if this is a silly question. Also I removed most variables from my makefile because they weren't working properly (gnu make tells me that $(myvar) should be completely replaces by the value of myvar, however the output of make was showing me that this was not happening), so I apologize for the ugliness and the more than 80 character lines.
acolibobj = acoLibInit acoGlobalDefs
acolibinterface: $(acolibobj).o
acoLibInit.o:
gcc -fPIC -g -c -Wall -I/usr/include/dc1394 -o acoLibinit.o acoCommands/acoLibInterface/acoLibInit.c
acoGlobalDefs.o:
gcc -fPIC -g -c -Wall -I/usr/include/dc1394 -o acoGlobalDefs.o acoCommands/acoLibInterface/acoGlobalDefs.c
When I run this makefile I get:
gcc -fPIC -g -c -Wall -I/usr/include/dc1394 -o acoLibinit.o acoCommands/acoLibInterface/acoLibInit.c
cc acoLibInit.o -o acoLibInit
gcc: acoLibInit.o: No such file or directory
gcc: no input files
make: *** [acoLibInit] Error 1
So far as I can tell, what's happening is that make is trying to compile AND link, even though I explicitly added the -c flag. When I run "gcc -fPIC -g -c..." myself (from bash), I do not get any problems at all. Why does make go on to try "cc acoLibInit.o -o acolibInit"?
make is trying to build acoLibInit. It probably has built-in rule that specifies "whatever" can be produced by linking "whatever.o", which is why you get that cc line.
This line:
acolibinterface: $(acolibobj).o
expands to:
acolibinterface: acoLibInit acoGlobalDefs.o
(note the absence of .o on the first dependency). This is why it's trying to link acoLibInit.
Try this:
acolibinterface: $(addsuffix .o,$(acolibobj))
if you want only the .o files as dependencies for that target.
$(acolibobj).o expands to acoLibInit acoGlobalDefs.o. Thus, you're really saying:
acolibinterface: acoLibInit acoGlobalDefs.o
Simply define acolibobj = acoLibInit.o acoGlobalDefs.o and use acolibinterface: $(acolibobj).
Unfortunately yes.
I have my shared library compiled, the linker doesn't complain about not finding it but still I get undefined reference error. Thinking that I might be doing something wrong I did a little research and found this nice, simple walkthrough:
http://www.adp-gmbh.ch/cpp/gcc/create_lib.html
which I've followed to the letter but still I get:
$ gcc -Wall main.c -o dynamically_linked -L.\ -lmean
/tmp/ccZjkkkl.o: In function `main':
main.c:(.text+0x42): undefined reference to `mean'
collect2: ld returned 1 exit status
This is pretty simple stuff so what's going wrong?! Is there something in my set up that might need checking/tweeking?
GCC 4.3.2 Fedora 10 64-bit
Change:
$ gcc -Wall main.c -o dynamically_linked -L.\ -lmean
to:
$ gcc -Wall main.c -o dynamically_linked -L. -lmean
You probably meant to do this:
$ gcc -Wall main.c -o dynamically_linked -L./ -lmean
which is OK, but the trailing / is redundant
How was the library created? Libtool?
Show us an ls -l of your current directory, and look at what gcc -v <rest of your command> says (that gives details of what gcc is doing).