I am trying to get mingw gcc to work.
I need it to link with libopengl32.a.
Said file exists in C:/mingw/lib.
I used g++ as follows:
g++ -L"C:/mingw/lib" main.o -o test.exe -llibopengl32.a
It has no trouble finding the includes, it just complains that it can't find the library.
It seems unable to find any other library as well.
Also: I installed all the mingw components manually by downloading them from sourceforge, since using the automatic installer produced a broken installation on my system.
The -l flag automatically adds the lib prefix and the .a extension- you want:
g++ -LC:/mingw/lib main.o -o test.exe -lopengl32
Note you don't need the quotes around the path either. You could also just specify the whole library name & path:
g++ main.o -o test.exe C:/mingw/lib/libopengl32.a
As regards your installation problems, use either http://tdragon.net/recentgcc/ or http://nuwen.net/mingw.html - using the MinGW site itself is a recipe for pain.
You need to use -lopengl32 without "lib" and ".a"
Related
I want to use a shared library (resides in a custom directory) into an executable.
I've created this makefile
all: SayHello
SayHello: compiledObjects/SayHello.o myLib/libNames.so
g++ compiledObjects/SayHello.o -o SayHello -Icommons -LmyLib -lNames
compiledObjects/SayHello.o: SayHello.cpp
g++ -c SayHello.cpp -o compiledObjects/SayHello.o
myLib/libNames.so: commons/Names.cpp commons/Names.h
g++ -shared -fPIC commons/Names.cpp -o myLib/libNames.so
That create correctly the executable and shared library infact I can Execute the program using this command
LD_LIBRARY_PATH=/custom/path/to/lib/myLib/libNames.so
./SayHello
How can I execute ./SayHello without specify LD_LIBRARY_PATH?
I'm not using any IDE and I'm on linux.
Use the -rpath option to link your executable. See the ld(1) manual page for more information.
P.S. Your makefile appears to have a bug. If you successfully make your program, and immediately run make again, looks like your makefile will attempt to recompile the program again, even though nothing has changed.
After all, the whole purpose of a makefile is to avoid doing unneeded compilations.
The SayHello.o build target should be compiledObjects/SayHello.o.
You need to tell g++ to pass the -rpath option to the linker using -Wl,-rpath. Also, you need to specify a path to the -rpath option.
Putting it all together your last build step should look like this:
SayHello: compiledObjects/SayHello.o myLib/libNames.so
g++ compiledObjects/SayHello.o -o SayHello -Icommons -LmyLib -lNames -Wl,-rpath=/custom/path/to/lib/myLib/
Relative RPATH:
If you want to specify an RPATH relative to your binary you should use
$ORIGIN as a placeholder: -rpath='$ORIGIN/rel/path'.
I have installed SDL2. I can link my program with
clang++ -lSDL2 -lv8 main.o test.o -o nano8
However, for distributing reasons, I'd like to give SDL2 away with the binary, and hence i've copied libSDL2-2.0.0.dylib under /myapp/lib/libSDL2-2.0.0.dylib
As for the documentation, #executable_path should allow me to link to that dylib instead of the one in /usr/local/lib, but if I run
clang++ #executable_path/lib/libSDL2-2.0.0.dylib -lv8 main.o test.o -o nano8
I get the error
clang: error: no such file or directory: '#executable_path/lib/libSDL2-2.0.0.dylib'
How to set the search path for a dylib?
This is a pain to get right.
I assume that /myapp can be anywhere in the filesystem, and want to load the library from #executable_path/../lib/libSDL2.dylib?
If so you have to use the Run Path and copy and modify the library during linking (this needs to be done every build):
cp /usr/local/lib/libSDL2.dylib build_dir/lib.
Change the install name of the .dylib using install_name_tool:
install_name_tool -change /usr/local/lib/libSDL2.dylib #rpath/libSDL2.dylib build_dir/lib/libSDL2.dylib
Link against build_dir/lib/libSDL2.dylib and set the rpath during linking:
cd build_dir/bin
clang++ obj_dir/main.o obj_dir/test.o -o nano8 -L ../lib -lv8 -lSDL2 -Xlinker -rpath -Xlinker "#executable_path/../lib"
I have not tested this and there is likely to be errors. Use otool -L to examine the library references in both the binary and the libraries in order to home-in on this issue.
A cleaner way:
Install your binaries into /usr/local/bin and provide any .dylibs to be installed into /usr/local/lib. This is better as /usr/local is the place for user-binaries and you don't need the faff above.
So I had successfully been using cmake and boost in my project.
I wanted to start incorporating armadillo (4.400.1)
I use enivronment modules (http://modules.sourceforge.net/) on my system.
I built with gcc-4.8.1.
CentOS 6.4.
I installed OpenBLAS (0.2.10) and armadillo from source and created environment modules.
In the past I only needed to prepend LD_LIBRARY_PATH with lib directories, but this was not sufficient for armadillo, as I was getting linking errors (unable to find lib) for the following:
g++ example1.cpp -o example1 -O2 -larmadillo
Using the -L option works:
g++ example1.cpp -o example1 -O2 -larmadillo -L${ARMADILLO_HOME}/lib
I am already placing the armadillo lib directory in LD_LIBRARY_PATH. How do I set environment variables so the following will link without error?
g++ example1.cpp -o example1 -O2 -larmadillo
I had to place the armadillo lib directory in the environment variable LIBRARY_PATH not LD_LIBRARY_PATH
Doing this allowed the linking to proceed without error when issuing the command:
g++ example1.cpp -o example1 -O2 -larmadillo
In Ubuntu 12.04.1 LTS I created a .so library file using this code:
g++ -c -Wall -Werror -fPIC someCode.cpp
g++ -shared -o libSomeCode.so someCode.o
I need to use that library file within an executable. But when running the .exe it cannot find the .so file. So I have to copy the library to /usr/lib/. I tried using this command (without success):
export LD_LIBRARY_PATH=/home/personalFolder/Desktop/codeFolder:$LD_LIBRARY_PATH
Is there a way to avoid copying the .so to /usr/lib/?
Thanks in advance.
Adding "; \" solved my problem.
I have a small project to create in a course at my University that requires using the Crypto++ libraries. The requirement is that we don't include the whole source code/binary files of Crypto++ but link it from an outside directory. (E.g. C:\cryptopp). This is because the reviewer will link his/her own directory to asses my code.
Now, I am really bad at creating Makefiles and don't understand the content of them completely.
I am using MinGW on Windows 7.
So my main question would be, what do I need to write in the Makefile to use Crypto++ in my project from an outside folder?
Suppose you have the following makefile:
unit.exe: unit.o
g++ unit.o -o unit.exe
unit.o: unit.cc unit.h
g++ -c unit.cc -o unit.o
In order to modify it to use an external library you have to use the GCC -I and -L options:
unit.exe: unit.o
g++ unit.o -o unit.exe -L /c/cryptopp -l ws2_32 -l cryptopp
unit.o: unit.cc unit.h
g++ -I /c/cryptopp -c unit.cc -o unit.o
Often a makefile would contain a variable that is passed to the compiler and a variable that is passed to the linker, for example CFLAGS and LDFLAGS. If that is the case, then it might be easier to add the "-I" and "L" options to the compiler and linker variables.
See also here for a way to comiple CryptoPP.