I am using g++ version 4.4.3 on Ubuntu OS. According to this matrix here it is supposed to support also std::atomic. Each time I use
#include <atomic>
the compiler gives me an error and says error: atomic: No such file or directory.
Have you experienced the same problem?
I am compiling using the following line
g++ -std=c++0x -Wall myCode.cpp -o myApp</code>
Try #include <cstdatomic> instead.
Related
I'm trying to compile a program that I've been able to compile on several other Debian environments with no issues using the C11 <threads.h> library on a relatively fresh install of Debian Bullseye with "gcc (Debian 10.2.1-6) 10.2.1 20210110" installed
with the command
gcc -o <progname> -O3 -Wall -Wextra -std=c11 -lpthread <sourcefile>
and I'm getting a string of linker errors in the form of
undefined reference to 'mtx_unlock'
as well as mtx_lock mtx_init thrd_create etc.
But I'm not getting an error saying the threads.h file is absent. I tried removing the -lpthread argument from the compilation command but this changed nothing.
What is going wrong?
The correct command line parameter seems to be -pthread without the l.
I am trying to compile this this source code (https://sites.google.com/site/bgcsoftware/) on a mac. I installed both hdf5 and gsl using homebrew.
Would you know what the problem might be?
Thank you in advance!
h5c++ -Wall -O2 -o bgc bgc_main.C bgc_func_readdata.C bgc_func_initialize.C bgc_func_mcmc.C bgc_func_write.C bgc_func_linkage.C bgc_func_ngs.C bgc_func_hdf5.C mvrandist.c -lgsl -lm
clang: warning: treating 'c' input as 'c++' when in C++ mode, this behavior is deprecated [-Wdeprecated]
bgc_main.C:17:10: fatal error: 'omp.h' file not found
#include <omp.h>
^~~~~~~
1 error generated.
bgc_func_mcmc.C:12:10: fatal error: 'omp.h' file not found
#include <omp.h>
^~~~~~~
1 error generated.
It looks like clang is the actual compiler being used. When compiling OpenMP with clang you need to pass the -fopenmp flag.
Try adding the -fopenmp flag like this:
h5c++ -fopenmp -Wall -O2 -o bgc \
bgc_main.C bgc_func_readdata.C bgc_func_initialize.C \
bgc_func_mcmc.C bgc_func_write.C bgc_func_linkage.C \
bgc_func_ngs.C bgc_func_hdf5.C mvrandist.c -lgsl -lm
The -fopenmp flag tells the compiler replace the code marked with #pragma omp ... with generated parallel code and should automatically add the correct -I include flags behind the scenes.
You should be able to run
h5c++ --help | grep openmp
To see other openmp related flags, depending on your compiler/OS.
adding -fopenmp did not help. However, the original code did run when I installed:
brew install --build-from-source libomp
I'm working on porting a windows project to linux so I am trying to learn/setup my build pipeline on linux(ubuntu). I use clang on windows and would like to use clang/llvm to compile my code on ubuntu but I am having an issue linking the c runtime library to my code. Here's an example of what I am trying to run just so I can set up the build scripts,
// -- system includes
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
// -- my includes
#include "crt.h"
int main() {
char title[] = "Text";
int title_length = strlen(title);
// -- sending string and length to platform dependent code
CreateBox(title, title_length);
return(0); }
After installing clang 3.4 on Ubuntu 14.04 LTS I run the above code as well as platform dependent code from the terminal,
clang++ -c main.cpp box_linux.cpp
The file compiles without error. Let's say I had I use the following command when trying to link,
ld main.o box.o
I get back the following error every single time,
ld: warning: cannot find entry symbol _start; defaulting to 00000000004000b0
In function 'main':
(.text+0x30): undefined reference to 'strlen'
I try linking libc++, libstdc++ but nothing seems to work. I am admittedly very, very new to linux and clang on linux so I apologize in advance. I have checked different questions here on stackoveflow as well as ubuntu's forums and LLVM's forums/docs to no avail. If anyone could point me in the right direction it would be greatly appreciated.
If you are using clang (or gcc) on linux you don't have to do the linking on your own. You can let clang do the linking for you and it will select the necessary libraries for your system just remove the -c flag form command line or use clang main.o. Clang understands that a .o file is already an object file and passes it on to the linker.
If you realy want to invoke ld on your own then start with clang++ -v main.cpp. The -v switch let clang print the invocation command for ld which e.g., looks like this:
/usr/bin/ld" -z relro --hash-style=gnu --build-id --eh-frame-hdr -m elf_x86_64 -dynamic-linker /lib64/ld-linux-x86-64.so.2 -o a.out /usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crt1.o /usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crti.o /usr/lib/gcc/x86_64-linux-gnu/4.8/crtbegin.o -L/usr/lib/gcc/x86_64-linux-gnu/4.8 -L/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu -L/lib/x86_64-linux-gnu -L/lib/../lib64 -L/usr/lib/x86_64-linux-gnu -L/usr/lib/gcc/x86_64-linux-gnu/4.8/../../.. -L/data/home/user/bin/../lib -L/lib -L/usr/lib /tmp/test-574b88.o -lstdc++ -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc /usr/lib/gcc/x86_64-linux-gnu/4.8/crtend.o /usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crtn.o
on my Ubuntu 14.04 LTS.
I'm currently trying to compile a dynamically linked library (for a plugin system) using Windows and MinGW.
I compile each objects using this command line :
mingw-g++ -fPIC test.cpp
And the library using this line:
mingw-g++ -rdynamic -shared -Wl,-soname,test.so.1 -o test.so test.o
It doesn't work at all (using GCC with Linux, a similar line works though) : fPIC and rdynamic are ignored for some reason.
And while trying to make the library, it fails because the compiler try to link it with objects that are supposed to be resolved as I dynamically link it with the main binary.
So how do you compile this using MinGW?
Thanks :) !
-fPIC and -rdynamic are ignored because they are unused for Windows.
Also, .so is not the correct output extension for libraries on Windows.
To make a shared library for/on windows with GCC:
mingw-g++ -c file.cpp -o file.o
mingw-g++ -shared -Wl,--out-implib,libfile.a -o file.dll file.o
No more, no less.
And, documentation is always lovely to have: http://www.mingw.org/wiki/sampleDLL
I have tried for a few days to compile -swc with -ljpeg but have not had any luck.
Here is what i have been doing.
in my jpeg_sample_linker.c, it has two headers
#include "AS3.h"
#include <jpeglib.h> //or #include "jpeglib.h"
and the rest of the file is pretty much empty but compilable(because all i want to do is to compile the file with the headers first).
And my gcc command is:
alc-on
gcc -swc -ljpeg jpeg_sample_linker.c -o jpeg_sample_linker.swc
alc-off
And, gcc keeps on saying it cannot locate libjpeg.h
i have also tried
alc-on
gcc -swc -I/usr/local/include -L/usr/local/lib -ljpeg jpeg_sample_linker.c -o jpeg_sample_linker.swc
alc-off
It still reported the same error "error: jpeglib.h: No such file or directory".
May i know how i could fix this compilation error?
Billion thanks
G
What a bummmer,
the compilation can be solved by editing gcc in /Library/alchemy-darwin-v0.5a/achacks
or
moving everything in /usr/local/lib and /usr/local/include to
to $ALCHEMY_HOME/usr/local/include and $ALCHEMY_HOME/usr/local/lib
!