I must say, I'm new to using Boost libs, but I have used them for a few of my projects, and have been super pleased with them.
Now, I would like to get all files with certain extension in one of my folders, so, looking it up online, I found this>How to get list of files with a specific extension in a given folder
I'm using Code Blocks on Windows 7.
I have done everything it seemed required, and when I try to compile it, I get three errors>
C:\boost_1_58_0\boost\system\error_code.hpp|221|undefined reference to
boost::system::generic_category()'|
C:\boost_1_58_0\boost\system\error_code.hpp|222|undefined reference to
boost::system::generic_category()'|
C:\boost_1_58_0\boost\system\error_code.hpp|223|undefined reference to
`boost::system::system_category()'|
I was looking it up online, and found that, besides pointing my "Search directories (compiler and linker) to boost installation, I need to point it directly to boost system lib somehow.
I tried -lboost_system in my Linker settings, but that didn't solve it.
I'm hardly an expert here, so I'm asking you guys if you can help me.
Does anyone have any ideas?
You need to provide the path where your lib is with the -L option of GCC.
Check this section of Boost documentation
Related
I am building a C++ project on my Ubuntu 64bit system using a provided Makefile, and this project also provides an API library for developers.
The compilation was successful, no errors at all, but when I try to include in my files the API libraries provided in the "api" folder, then g++ complains about undefined references.
It is not a problem about dependencies (I already built the project succesfully), in fact the missing references are about classes and functions provided by the project, but they are in some specific (sub-)folders (I don't know which ones!), I guess in some .so files, and g++ is not finding them, probably because it does not know they are in those specific subfolders.
It is not the first time this happens when trying to use APIs from any project, then I think I am missing something or I am doing something wrong in general when trying to use the libraries provided in a project.
In particular, the main problem is that I don't know how to tell the compiler where some classes or data structures are declared, and moreover I don't know how to locate them in order to know where they are.
Usually, a workaround I use to avoid this problem is to run make install (as root or using sudo) so that libraries and APIs are installed in standard folders (like /usr/include or /usr/lib) and if I do this thend I can include the API libraries using #include <library>, but in this last case it didn't work either, because perhaps some required files containing the not found classes/structures are not properly installed in the right folders in the system.
Another workaround I used sometimes is to try to put all the project files in the same folder instead of using the project folder structure, but clearly this is not good! :-)
But I noticed that several other people managed to use the APIs, then apparently they know some way of finding the files containing the "undefined" references and including them in the compilation.
Then my general question is: given a "classic" C++ project based on "Makefile" files and with usual folder names like src, lib, build, bin, etc., if I want to write C++ files using the libraries provided by the project, but the compiler complains about undefined references, how can I find the files (.so or .o or .cpp) containing such references? Is there any tool to find them? And how can I tell the compiler where they are? Should I use some command-line option for g++ or should I use the #include macro in some smart way?
PS I also tried to use the pkc-config linux tool to get right options to use for compilation and they were available, but the compiler still complains about the undefined references.
Some more degails about the project i tried:
For interested people a link to the project is below:
https://github.com/dreal/dreal3
And instructions on how to build it:
http://dreal.github.io/download/
Look into the -rpath linker option - specifically with the "$ORIGIN" argument. That lets you find libraries relative to your executable location so you don't have to install them to the standard locations but just need to put them somewhere known, relative to the executable. That should help you with one piece of the puzzle.
Note: -Wl, can be used to pass arguments to the linker via g++.
As for pointing the compiler/linker at a library so it can resolve undefined references by using that library, use the -l (that's lowercase L) option to specify the library name and -L to specify directories to search for libraries.
As for looking into a library (.so) file to see what symbols are in there, you have a few tools at your disposal: objdump, nm, readelf and objcopy.
My problem is I am not able to include a library into my current project. [The way to include a library in netbeans into a project is to link it via linker to the project]. However, in my current project(which is written by another programmer who left the organization) the option of linker is not appearing. I have attached a screenshot. I am faced with the issue that the option of linking the library via linker to my current project is not appearing in IDE. Can someone please please help me out. I'll be highly thankful to you for the same.
Please guide me as to how should I link the library to my project. I have really spent a lot of days doing it but I did not succeed.
Assuming you are only interesting in libspatialindex:
Make sure you have the appropriate files installed: try a locate libspatialindex and see where it is installed. You could have a *.a, *.so or similar extension. Note the path.
Go into your project root directory, i.e: /home/keira/netbeans/projects/myproject
Try: gcc -i main.cpp -L/usr/lib/ -lspatialindex -o myfile
Replace the -L/usr/lib with the actual location where you know the library is at.
The cxx link flag is usually the name of the library with an -l prefix. If for example the name found in the system is libspatialindex.so then its a good bet to try with -lspatialindex.
There is a way to find the actual flags on Debian & Ubuntu systems but I cannot atm remember it. Alternatively you can always look on google or read the library documentation.
When you usually see linker errors with undefined functions, etc, it means you're not linking, provided you have included the headers and they are found.
Now for Netbeans, I assume there is the option of passing extra arguments to the compiler. In this case, all you need is the -lspatialindex flag, provided Netbeans knows where to find the library and the headers. That is how it works in KDevelop and other IDE's I have used.
Alternatively if you want more control and more automation, you may want use a tool like cmake.
I'm trying to link the thread library of boost 1.50.0 and am having some problems. The problem is that the implementation of the thread cannot be found.
I've checked around here, on random sites and on the official manuals and concluded that there can only be one reason for this (since the actual library I'm linking contains the correct files). There is no auto-linking in MinGW. This means there can be no platform implementation for the threads available (and hence the error).
One of the errors I'm getting is:
undefined reference to `imp__ZN5boost6thread4joinEv'
that comes from myTread.join().
So my questions is, what is the library (or libraries) I need to link in addition to the boost thread library (in this case named libboost_thread-mgw46-mt-1_50.a)?
And furthermore, is there any documentation for all library dependencies in boost?
I could of course be completely wrong, so any help appreciated!
Currenty I'm linking only boosts libraries; threads, chrono and system.
EDIT
To clarify, I'm linking with the following command:
g++ -LPATH_TO_BOOST\lib -o test-boost-thread.exe src\test-boost-thread.o -lboost_thread-mgw46-mt-1_50 -lboost_chrono-mgw46-mt-1_50 -lboost_system-mgw46-mt-1_50
I've tried changing positions of the libraries, but that didn't help.
In your case, given the file name that you posted, the linker line would be -lboost_thread-mgw46-mt-1_50 (remove lib and .a/.so/.lib). There might be (or you might want to create) a symlink that points to it like libboost_thread.a -> libboost_thread-mgw46-mt-1_50.a, in which case you can use the shorter -lboost_thread.
Hmm, seems like I completely forgot about the BOOST_THREAD_USE_LIB flag. Setting this made it work.
Strange error though.
I'm trying to port/build some of my code written for gcc (on linux) as a dll on windows. First I tried to build in under VC++ but there were so many errors/warnings (mainly in VC's own include files, which didn't really make much sense to me :)) so I installed MinGW distro (which includes Boost libraries). Compilation went quite smoothly, however linking failed with undefined references to functions from boost libraries. The "-t" parameter showed that the linker doesn't actually use the boost libraries for some reason (yes, the -L path is correct, the libraries are there, linker doesn't complain when I use -l).
After much googling I found out that the order is the problem, that I have to place my -l parameters after all my .o files (because of dependencies). This seemed to solve all the problems except one undefined reference to thread library. Again -t showed that this library is actually not used by the linker (not in the list) the others are (I use boost_system and boost_date_time as well). I played with the order of the parameters again but the result was the same. Any idea what am I missing?
The error is:
c:/x5/cpp/build//timed_cond.o:timed_cond.cpp:(.text$_ZN5boost6detail24basic_condition_variable7do_waitINS_11unique_lockINS_5mutexEEEEEbRT_NS0_7timeoutE[bool boost::detail::basic_condition_variable::do_wait<boost::unique_lock<boost::mutex> > (boost::unique_lock<boost::mutex>&, boost::detail::timeout)]+0x246): undefined reference to `_imp___ZN5boost11this_thread18interruptible_waitEPvNS_6detail7timeoutE'
I use same versions of Boost library (1.44.0) on both platforms
Ok, I found the answer. Looks like the problem is in boost libraries being static in MinGW-distro. Normally they are configured to be linked dynamically and that caused above issue. This answer explains it...
I'm wondering if there are any simple ways to link boost libraries (all or individual) via some entry like....
-lSDL_ttf
The above links SDL's True Type Font library. Can this be done with boost? If so, I'm not sure what file I'm linking for to link. I'm currently using boost_1_40_0.
If this isn't possible, or there are better ways to do this, I'd be happy to hear them.
P.S. I'm using the CodeBlocks IDE.
Most boost libraries don't need to be linked as they are header only.
For those that are not header only, see the instructions here on the naming conventions and make sure you put the folder containing the boost libraries in your library search path if you want to avoid specifying it explicitly.
For Xcode 7, A few updates to this post:
a. Following installation instructions the following link, I placed the zipped file in /usr/local, resulting in an installation directory of:
/usr/local/boost_1_60_0
http://www.boost.org/doc/libs/1_60_0/more/getting_started/unix-variants.html
b. As stated on the above page, many of the Boost libraries are "header only." In other words, there is no library, and you don't have to link the libraries; there is nothing to link! If you try and link them, you will get an error! You just have to specify the header location, like so:
Of course, if you're using a Boost library that must be compiled, you may have to link it differently, but it's important to keep this in mind.
c. Be sure to check the permissions on the installation directory. I installed as root, and had to do a chmod 755 on the install, as show below. If permission are not set, you will get the generic and utterly unhelpful "library not found" error.