When I try to compile a vala or genie program needing libgee, I get undefined references to gee_array_list_new, etc. I have libgee installed from source; its .so file is right there in plain sight in /usr/local/lib, its other files as they should be. But when I install libgee with my distro's package manager, the vala program links fine! I'm looking for a difference to explain this, but am stumped. The libraries are slightly different versions, but not by much.
Does valac somehow fail to look in /usr/local/lib? What are likely explanations?
Most likely, you pkg-config --libs gee-1.0 doesn't include -L/usr/local/lib`.
Make sure you have PKG_CONFIG_PATH=/usr/local/lib/pkgconfig if you want valac to link with /usr/local/lib libraries.
Related
I made a program today, and I was wondering on how exactly to make it an executable. I've researched and I've came up with using srlua. I've asked this previously, but I usually mess up on the same instruction. I was told to 'compile srlua' While I know exactly what to do right after I compile srlua, I don't know how to compile them right now.
I've gone through a few YouTube tutorials, and I managed to find one but only in Spanish. I was able to slightly follow along until he downloaded a precompiled version of srlua, where the download link is no longer there at the same page he was at.
Would anyone be able to explain what they're trying to say?
You need to tell CMake where the Lua files it needs are.
For me, the Lua includes are in /usr/include/luaX.X, where X.X is your version number, e.g. 5.3. The Lua libraries may be in /usr/lib (with filenames like libluaX.X.so).
If the locations differ for you, you can try find / | grep "lua.h" and find / | grep "liblua".
Once you've located the folder which lua.h is in, and the appropriate library file like liblua5.3.so, you need to add these to the CMakeLists.txt file in the srlua folder.
For example, using lua5.3, you might replace this line:
include_directories(${LUA_INCLUDE_DIR})
with this one:
include_directories(/usr/include/lua5.3)
And for the libraries, you might replace this:
target_link_libraries(glue ${LUA_LIBRARIES})
target_link_libraries(srlua ${LUA_LIBRARIES})
with this:
target_link_libraries(glue /usr/lib/liblua5.3.so)
target_link_libraries(srlua /usr/lib/liblua5.3.so)
After this, run cmake ./ in the srlua folder, then run make. srlua should be built.
Note: you may also have to remove the line find_package ( Lua REQUIRED ), it was a false error for me (it only built when I removed that line).
I installed boost using brew install boost in order to use odeint library (the odeint webpage says : odeint is a header-only library, no linking against pre-compiled code is required).
I am on Mac Yosemite 10.10.5 . Now when I cd to /usr/local/include, I can see boost directory there. Inside boost (/usr/local/include/boost) there are all the header files I needed for my project, along with the numeric/odeint directories needed for my specific purposes. At the same time, when I cd to usr\local\lib, I can see a lot of libboost_* .dylib and .a files.
However, when I try to compile a c++ file that I temporarily save in ~/Downloads (the first header is #include <boost/array.hpp>), I got the error fatal error: 'boost/array.hpp' file not found.
I am inexperienced in programming, and I really appreciate your help! Thank you!
Use the following include statements and let us know if it works.
#include <boost/numeric/odeint.hpp>
#include <boost/numeric/ublas/matrix.hpp>
If not, some additional info is needed. What is your BOOST version, what is the structure of the /usr/local/include/boost directory, how about including other (non-boost) headers from /usr/local/include (maybe compiler include path is broken).
I asked my professor about this. He gave very detailed explanation, and I think I should share so that everyone can benefit from it:
Theory:
Your compiler needs to know where these files are. You need to find a way to tell it where the files are.
Depending on how you are doing the compiling there will be different solutions. If you are compiling via the command line, use something like
g++ -I/usr/local/Cellar/boost
The -I stands for "include files". There is a similar g++ "switch" called -L for libraries when you get to that stage.
There is also a whole series of tools to tell the compiler how to search for include files. The directory /usr/local/include is almost certainly on the list of places for it to look.
If you are using "make" and the associated tools for compiling, you can add the include directories to part of the "Makefile". Again, the details are different for every setting.
Bottom line -- you'll need to learn more about your compiler system. Find manuals and examples for your specific tools and system. Learn how those tools work and where to specify the boost libraries. Read the boost manuals and learn where they store files and what all the names are for the different directories where these files are stored.
It's not fun work, but it is worthwhile learning about how all the parts get put together.
I'm trying to install OpenCV on Windows. Following are how I installed it:
Download OpenCV 2.4.2.exe from sourceforge.
unarchived it.
open Eclipse CDT.
Add C:/opencv/include/opencv to "Includes"
Add opencv_highgui, opencv_core, opencv_ml... to "Libraries"
Create a small project and compiled it.
The compiler complained about "opencv2/core/core_c.h：No such file or directory"...
I remember that when I install OpenCV on Ubuntu, I did compiled the project (it took quite a bit of time). Do I have to do the same thing on Windows? Or is any other thing causing this error?
Thanks.
You should add correct directories to includes.
Since you added C:/opencv/include/opencv, there is no way for compiler to find C:/opencv/include/opencv2/core/core.h.
I believe you should enter C:/opencv/include/ to includes directories as well.
I'm very inexperienced with Linux and the terminal, but I'm trying to learn. I've also never included an external library before. Now I need to include the Boost.Asio library in a program being developed in Ubuntu with G++.
Could someone very kindly and very carefully explain how to go about this, from the beginning?
EDIT:
Expanding on the original question: if I need to send this code to someone else for them to run it on a completely separate machine but in the same environment, how do I take that into account? If this whole process involves literally placing library files into the same folder as the code, do I just send those library files along with the .cpp to this other person?
You have mentioned you are using Ubuntu, so the simplest way to use boost is to first install libboost-all-dev package (from synaptic), which will install everything for you including those that needed to be compiled. Then you just need to use g++ in the usual way.
Please note that whether the version is what you want, if not, you may want to install it yourself. On the other hand, boost is mostly header only library, so you only need to extract the files (right click in Ubuntu...) to a folder and link to it while compiling:
g++ hello_world.cpp -I boost_1_49_0/boost
where the last one specify the path for compiler to find the boost headers (please use absolute path).
If you want to send your program to others, dont copy only some boost files, it does not work because of the dependence. Ask them to install the same environment as you while is easy (just unzip a file...).
I don't know about your specific IDE, or about Boost.Asio specifically, but in general:
Whenever you need to link to a library, there is a file named similar to lib???.a, which you need. You need to pass the -l??? flag to g++ to link to the file.
(I'm not too familiar with the details myself, so there might be other file formats and whatnot too...)
Regarding the edit:
The "right" way would be to just have them download the library themselves, and just pass -l??? to their linker. Including Boost in your source code will make it huge, and for no good reason... it's not like you include the STL in your code, after all.
You don't include the library, but instead you declare a dependency on it. Eg. consider you use autoconf and automake then you would add AX_BOOST_BASE1 to require boost and AX_BOOST_ASIO to require the ASIO libraries. In your Makefile.am file(s) you use BOOST_CPPFLAGS and BOOST_LDFLAGS macros and rely on the ./configure to set them properly. Then whoever consumes your code will have to run the well know ./configure script which will analyze the environment for the location of boost and setup appropriate values in the build environment so that the make succeeds.
Well at least this is the theory. In practice there is a reason the whole thing is better known as autohell. Alternatives exists, like CMake or boost's own bjam. But the synopsis is always the same: you declare the dependency in your build configuration and the destination location that consumes you product has to satisfy the requirement (meaning it has to download/install the required version of boost, in your case). Otherwise you enter into the business of distributing binaries and this is frowned with problems due to richness of platforms/architectures/distributions your application is expected to be deployed in.
Obviously if you use a different build system, like ANT, then you should refer to that build system documentation on how to declare the requirement for boost.
1: ax_boost.m4 is not the only boost detecting m4 library, there are other out there, but is the one documented on the GNU autoconf list of macros
I use statically linked sqlite database and in order to compile every next version I sometimes have to do minor changes in the list of object files used.
But sometimes the changes I have to make puzzles me.
For example prior to version 3_6_10 this order
{$L 'Objs\is.OBJ'}
{$L 'Objs\mbisspc.OBJ'}
was ok, but starting 3_6_12 the linker said
unsatisfied forward or external declaration _isspace
but changing the order to
{$L 'Objs\mbisspc.OBJ'}
{$L 'Objs\is.OBJ'}
helped.
As for the changes in sqlite, it really stopped to use c function isspace in 3_6_12 and started to use an internal equivalent so "isspace" keyword even don't appear inside the obj file.
So why does the order of linked object file with $L directive matter and where I can read more about this? I suppose it is something related to cross-usage of the listed obj files, but I will feel more safe if I understand what is going on
Thanks
Edit:
As of the comment by David Heffernan linking to his answer to this other question on linking .obj file in Delphi, I replaced linker by compiler, and added a the italic portion below:
C compilers use a multi-pass linker compiler that knows how to resolve forward and circular dependencies between .obj files.
Since the Delphi linker compiler is targeted at the Delphi language, and the Delphi language does not allow for that, the linker compiler does not allow for this either.
Pro: the linker compiler is much faster.
Con: you need to help the linker compiler a bit by placing the .obj files in the right order
, or by manually resolving the dependencies (see the above mentioned answer by David Heffernan)
.
--jeroen