I need to setup a make file to compile my code with the environment variable $BOOST_HOME pointing to the boost install directory. Currently I am compiling using the command
g++ -std=c++0x -Wno-deprecated main.cpp
How would I go about doing this, so that my code will compile for others if their boost install directory is different from mine?
Related
I am trying to troubleshoot a problem I have in using the library matplot++. I need someone to teach me how to fish here instead of giving me a fish, because I'm struggling to google search the right terms to solve my problem.
My folder structure is as follows
-music_vis
|-libs
|-3rd party
|-matplot
|-matplot.h
|-other_folders_for_matplot
|-wavs
|build.sh
|main.cpp
|thread_pool.hpp
build.sh is as follows right now:
g++ -Wall -lmatplot -I /$(pwd)/libs -g -o music_vis_cpp ./music_vis_main.cpp -lstdc++fs -std=c++17 -pthread
Everything 100% works in this shell script except for something within this section:
-lmatplot -I /$(pwd)/libs
For which I get the following error:
/usr/bin/ld: cannot find -lmatplot
collect2: error: ld returned 1 exit status
Is g++ spuriously looking in my /usr/bin/ for files? Shouldn't it be looking in $(pwd)/libs?
From what I have researched, I am also supposed to have .so files, but everything under the matplot folder is .cpp or .h files. Does this mean I installed the library incorrectly into my /lib/ folder? I cloned from github and simply copied into my /lib/ folder. Without the -lmatplot flag I get the following error:
Any thoughts, resources, guidance or guidelines on how to troubleshoot these problems in the future? Thanks friends.
I followed the instructions on the repo, but piggybacking off of Compiler not finding jpeg and png libraries , I added the following flag to the cmake. This created object files for me.
-DBUILD_SHARED_LIBS=ON
I was able to build a .so file by following the build instructions included in the matplot++ .md file, but supplying an extra flag -DBUILD_SHARED_LIBS=ON
From there, under the build folder, I found a .so file somewhere in the folder tree, moved that to my /lib/ directory, and ran the following shell script:
#!/bin/bash
g++ -I /$(pwd)/libs -L /$(pwd)/libs -Wall -g -o music_vis_cpp ./music_vis_main.cpp -lstdc++fs -std=c++17 -pthread -lmatplot
And this finally built my program. However it doesn't run because shared object file doesn't exist or something.
Edit: More steps to make the program run;
Create a folder on your filesystem you want to put your .so files into and then...
export LD_LIBRARY_PATH=/home/harrison/Documents/computer/cpp_packages/shared_object_lib/
I need to run this export line every time I restart my computer, so I just add it to my build script.
So the .so file is in two places, one necessary at build time and the other necessary at run time. My binaries can be run anywhere on my computer with this method.
I have 2 cpp files(with one main function) in /home/misha/proga/c++again folder. I built C/C++: g++ build active task and modified it to compile all files in the folder above. Now, I need to add one more task to call a binary. I think I should add one more entry in "tasks" to finally be able to run a code. Where can I read about how to write this second task? I am new to programming. Is my approach correct to run this code contained in two files? I also do not know where this binary lies. Is it tasks file in .vscode folder ?
I use Ubuntu 19.10 and VSC 1.46.1
In Terminal,
cd /home/misha/proga/c++again
Let's suppose your two cpp files are mainFile.cpp and file2.cpp
If g++ (so GCC) was not installed in your system, you can install it by running this command on the Terminal:
sudo apt-get install gcc g++
and, to compile the program (read about invoking GCC, you want warnings and debug information), write this command into the Terminal:
g++ -Wall -g mainFile.cpp file2.cpp -o yourprog
Then, you can run the program by typing:
./yourprog
It should work now. You could need to use the GDB debugger and GNU make (to be installed with sudo apt-get install gdb make)
Read also some C++ programming book and this C++ reference.
I do not understand your approach usualy your create a makefile and compile your cpp files
g++ -g -c -fpic -o name.o
at the end you link them
g++ name.o 2name.o and so on
If you create binarys you should store them in /usr/lib
and the name should libname.so you can acces them by using the -l argument
If I write this code and saved as a.cpp at ~/Desktop
#include <memory>
int main(){}
then input to bash:
cd /usr/bin
g++ -g ~/Desktop/a.cpp -o ~/Desktop/a
then the g++ will output plenty of messy code of errors.
I have found the reason is because it don't have authority to link XX.so library.
But if I add a 'sudo' , or set CWD to the path owned by user, g++ will work properly, as follows:
sudo g++ -g ~/Desktop/a.cpp -o ~/Desktop/a
or
cd ~/Desktop
g++ -g ~/Desktop/a.cpp -o ~/Desktop/a
Why do this happen? or how can I fix this?
You don't want to generate code directly in /usr/bin.
You generate your code in your user folder, maybe create a sub-directory called cppwork or something like that.
cd
mkdir cppwork
cd cppwork
g++ -g a.cpp -o a
Once you compiled in your directory, then you copy the file using install which will also take care of stripping the debug if any (i.e. the -g says to keep debug info—stripping is not mandatory).
sudo install -s a /usr/bin/a
As you can see, the place where I use sudo is with the install command.
That being said, I never use those directly. Now a day, I use cmake which means everything works automatically. But that would be a different discussion.
Thanks for every one. I have found the reason. It's because there is an executable program named 'array' in /usr/bin. And when CWD is /usr/bin, the compiler regard this 'array' as the c++ header <array>, so compiling error.
Then I need to find out why the compiler includes /usr/bin by mistake.
I wanted to use latest g++ compiler(4.9.1) on suse linux, but suse only supports an older g++ version. So, I took a latest source code from one of the gnu mirror sites and compiled it myself. Everything went fine. But when I tried to compile my test code using the built g++, the compilation fails with error,
"/root/home/include/c++/4.9.1/x86_64-unknown-linux-gnu/bits/os_defines.h:39:22: fatal error: features.h: No such file or directory".
I can find a "features.h" in "/root/home/include/c++/4.9.1/parallel", but I feel that it should be there in "/root/home/include/c++/4.9.1/" itself.
I copied "/root/home/include/c++/4.9.1/parallel/features.h" to "/root/home/include/c++/4.9.1/" just to see what happens. Now it complains with error "whcar.h" not found.
Have I missed something.
Here are the steps I followed to build g++.
1. /root/home/gcc_build/objdir# ../gcc-4.9.1/configure --prefix=/root/home/ --disable-multilib
2. /root/home/gcc_build/objdir# make -j16
3. /root/home/gcc_build/objdir# make install
4. /root/home/gcc_build/test# /root/home/bin/g++ --sysroot /root/home -m64 test.cpp
I resolved the issue by removing sysroot option and pointing c++ include and library path to my home directory. One thing I noticed was that the g++ source does not come with libc and c header files, and libc has to be installed seperately. But with sysroot option, g++ was trying to look all the header files in my home directory.
Below is the command I used to successfully compile the code.
/root/home/bin/g++ -I /root/home/include/c++/4.9.1 -L /root/home/lib64 -Wl,--rpath=/root/home/lib64 --std=c++0x -m64 test.cpp
Take a look at the GCC Directory Options. It is important to use the correct "specifier" as well (-isystem, -L, -B, -I etc)
I have 2 different g++ compilers on my computer:
one in the standard directory (C:\MinGW),
and one is a portable distribution.
Now I'm trying to link a c++ project.
The problem is, it is linked against boost libraries
compiled with the portable distribution of g++. The standard
installation directory is ofcourse included in the PATH environment
variable. So when I try to compile my project it will produce linker errors.
I tried to create a batch file which added the portable version's directory at the beginning of the PATH variable. With no luck. Maybe some one can help me out?
#echo off
set PATH=%~dp0..\c++\compiler\bin;%PATH%
REM cd /d "%~dp0"
..\c++\compiler\bin\g++ main.cpp ^
-std=c++0x -static-libgcc -static-libstdc++ ^
-I"../c++/include" ^
-L"../c++/lib" ^
-l"boost_serialization-mgw46-mt-1_52" ^
-l"boost_system-mgw46-mt-1_52" ^
-o output.exe -W -O2
pause
Note: I used "..\c++\compiler\bin\" befor the g++ command because I wanted to be sure it it used the right path, but ofcourse it doesn't work the way I expected.
Solved it by recompiling boost with the installed version of GCC.