I'm having trouble building a simple c++ program that tests out regex's from the boost library. The problem that I'm having is occurring in the linking stage and I don't know enough to fix the error on my own.
In the .cpp program that uses regexes I used the following include line.
#include <boost/regex.hpp>
I don't know enough to figure out what command I should use to build the program using g++. I tried using the following command line (and variations of it) to build the program.
g++ -I/usr/include/regex -L/usr/lib -llibboost_regex main.cpp -o regex_test
Other information that might be relevant:
Operating system: Arch linux
g++ version: 4.6.2 20120120 (prerelease)
Any help would be appreciated.
Assume you have installed Boost with the boost and boost-libs packages,
The header <boost/regex.hpp> should exist in /usr/include/boost/regex.hpp. You don't need to use any -I flags since /usr/include should be included by default.
You shouldn't need the -L flag either since /usr/lib should also be included by default when linking.
When using the -l flag to link with a library libfoo.so, the leading "lib" part should be removed.
The command line should therefore be:
g++ main.cpp -o regex_test -lboost_regex
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How to install c++ library on linux
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Closed 4 years ago.
I'm new to c++ and don't understand how to install a library on Linux (Mint). I want to use the GNU GMP library:https://en.wikipedia.org/wiki/GNU_Multiple_Precision_Arithmetic_Library
I downloaded the tar.lz file and installed it with
./configure
make
sudo make install
If I try to compile it, I get the error message that the header file "gmpxx.h" wasn't found. Where can I find this file? How do I compile it with the -lgmpxx -lgmp flags? I tried something like:
g++ test.cpp -o test -lgmpxx -lgmp
If the library is using the Autoconf system (which your does) then the default installation prefix is /usr/local.
That means libraries are installed in /usr/local/lib, and header files in /usr/local/include. Unfortunately few Linux systems have those added for the compiler to search by default, you need to explicitly tell the compiler to do it.
Telling the compiler to add a header-file path is done using the -I (upper-case i) option. For libraries the option is -L.
Like so:
g++ test.cpp -I/usr/local/include -L/usr/local/lib -lgmpxx -lgmp
The above command will allow your program to build, but it's unfortunately not enough as you most likely won't be able to run the program you just built. That's because the run-time linker and program loader doesn't know the path to the (dynamic) libraries either. You need to add another linker-specific flag -rpath telling the build-time linker to embed the path inside your finished program. The front-end program g++ doesn't know this option, so you need to use -Wl,-rpath:
g++ test.cpp -I/usr/local/include -L/usr/local/lib -lgmpxx -lgmp -Wl,-rpath=/usr/local/lib
The options can be found in the GCC documentation (for the -I and -L and -Wl options), and the documentation for ld (the compile-time linker) for the -rpath option.
If you install a lot of custom-build libraries, you might add the path /usr/local/lib to the file /etc/ld.so.conf and then run the ldconfig command (as root). Then you don't need the -rpath option.
Now with all of that said, almost all libraries you would usually use for development will be available in your distributions standard repository. If you use them the libraries will be installed with paths that means you don't have to add flags.
So I recommend you install your distributions development packages for the libraries instead.
I have a fresh install of OS X 10.11.4 that I immediately installed the Xcode toolchain on, then Homebrew, then Boost 1.60. In order to test that everything had gone well, I wrote the following code on my Desktop.
#include <iostream>
#include <boost/filesystem.hpp>
int main() {
boost::filesystem::path new_directory("hello");
boost::filesystem::create_directory(new_directory);
}
I then attempted to compile it as I usually have done with the following command.
$ clang++ test.cpp -o test -lboost_system -lboost_filesystem
I received the following error.
test.cpp:3:10: fatal error: 'boost/filesystem.hpp' file not found
#include <boost/filesystem.hpp>
This is how I have always compiled projects that link Boost in the past. I'm assuming that I have probably forgotten a step along the way that allows clang to search a specific path to dynamically link the libraries. What should I change in order for this compilation command to work?
For me, boost has been compiled and installed into a subdirectory of my home directory, so you'll need to modify the paths as appropriate for your homebrew installation:
flags="-std=c++1z -I/${HOME}/local/include -L${HOME}/local/lib -lboost_filesystem -lboost_system"
c++ ${flags} -o jared jared.cpp
First get the location of boost by doing the following:
brew info boost
From the image above, you can see that my location is
/usr/local/Cellar/boost/1.66.0
Then, to compile, use the following:
c++ -I /usr/local/Cellar/boost/1.66.0 main.cpp -o boost
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'm trying to include and compile
#include <json/json.h>
However even though I've installed it and included it on the project settings it wouldn't find the path.
here's what I've so far done:
path to libjson:
/usr/include/jsoncpp-src-0.5.0
options in eclipse gcc c++ compiler:
-Ijson_linux-gcc-4.5.2_libmt -O0 -g3 -Wall -c -fmessage-length=0 -ljson_linux-gcc-4.5.2_libmt
libraries in gcc c++ linker:
-L/usr/include/jsoncpp-src-0.5.0/include/
Anything else I forgot to do to make it work?
try adding -I/usr/include/jsoncpp-src-0.5.0 to compiler options
-L indicates where to find shared libraries (e.g. .so)
-I is the search path for the header files.
If the problem occurs during compilation (json.h not found), then you have indicated the wrong -I
If it occurs during linking (symbol not found), then you have indicated a wrong -L, a wrong -l, or forgot to run ldconfig
I installed Boost via sudo apt-get install libboost-all-dev on the most recent version of Ubuntu. Now I want to compile a project that uses the Boost.Serialization library, which needs to be linked.
I've tried many variants of the following, without success:
gcc -I /usr/lib code.cpp -o compiled /usr/lib/libboost_serialization.a
and
gcc -I /usr/lib code.cpp -o compiled -l libboost_serialization
The error message is:
error: ‘split_member’ is not a member of ‘boost::serialization
`
What am I missing?
You are having troubles with compiling your code, not linking. On that stage it has nothing to do with libraries. At that point the fact that you have to link against something is irrelevant.
Make sure you are including boost/serialization/split_member.hpp directly or indirectly and get your code compiled first.
On a side note, -I flag is used to specify path to include files and not libraries. For libraries, use -L. But if you have installed Boost from apt, then it should already be in the path and so no additional -I or -L should be required. And when you specify -l, you have to emit lib from the beginning of library name and not put a space between a flag and its argument. Assuming working code, something like this should do:
g++ code.cpp -o compiled -lboost_serialization
I'd also recommend you pass -Wall flag to make compiler be more verbose and warn you about possible mistakes in your code.
split member is a problem with compiling where boost is assuming there are split calls for serialize and deserialize.
http://www.ocoudert.com/blog/2011/07/09/a-practical-guide-to-c-serialization/