I'm using CLion as my IDE for C++ development and I'm trying to get Eigen included.
How do I do this?
I've downloaded and unzipped Eigen and placed it in C:/ (Which I've read online is the path where CMake looks for libs when you use find_library())
In the CMakeLists.txt I've added
find_library(Eigen3 3.4 REQUIRED NO_MODULE)
add_executable(Lecture03 main.cpp)
target_link_libraries (Lecture03 Eigen3::Eigen)
But then it can't find Eigen, I get the following error when reloading my CMakeLists:
CMake Error at CMakeLists.txt:6 (find_library):
Could not find Eigen3 using the following names: 3.4
My question is, what did I do wrong? Did I place the Eigen folder in the wrong directory? Can I change where CMake looks for libs in CLion?
Eigen (https://eigen.tuxfamily.org/index.php?title=Main_Page) is a template library. That means it is header only, there is nothing to link against.
For CMake that means you can use find_path to find the header file
The solution ended up being to use
include_directories(C:/CPP_Libs/Eigen3)
in my CMakeLists.txt, and
#include <Eigen/Dense>
in whichever file needs it
Related
I'm trying to use external libraries (specifically opencv) with C++ but I'm having some trouble. It seems like using vcpkg is the easiest way to go about this. So far I've followed these tutorials: https://www.youtube.com/watch?v=b7SdgK7Y510 and https://www.youtube.com/watch?v=iZeK3Ie5Fz0 but I keep getting these errors when I try to include a file:
cannot open source file "opencv2/core.hpp"
'opencv2/core.hpp' file not found
The quick fix provided by vscode says to install opencv through vcpkg but I've already done that. I've linked vcpkg according to the tutorials and included the path to the cmake toolchain file in my settings.json file.
Here is the change I made to my settings.json file:
{
"cmake.configureSettings": {
"CMAKE_TOOLCHAIN_FILE": "/Users/oliverpasquesi/coding/dev/vcpkg/scripts/buildsystems/vcpkg.cmake"
}
}
Here is the CMakeLists.txt file (it is the same as the one from the 2nd tutorial listed):
cmake_minimum_required(VERSION 3.0.0)
project(photoText.cpp VERSION 0.1.0)
add_executable(photoText.cpp main.cpp)
Here is the includePath portion of the c_cpp_properties.json file (including the 2nd path doesn't make any difference in the errors being thrown):
"includePath": [
"${default}",
"/Users/oliverpasquesi/coding/dev/vcpkg/installed/x64-osx/include/opencv2/**"
]
If it's useful, I'm using vscode 1.49.2 on a mac running Darwin x64 21.5.0.
I appreciate the help!
You need to reference your library in the CMakeLists.txt file as well, since that's the file CMake uses to prepare your project for a build.
A modern way to do this is to add two lines:
A find_package() line to find the libraries you are using. As you already referenced the vcpkg.cmake toolchain file, CMake should be able to find any libraries already installed by vcpkg when you add that line. See https://cmake.org/cmake/help/latest/command/find_package.html for documentation.
A target_link_libraries() line that lists libraries to link against your project. See the CMake documentation here: https://cmake.org/cmake/help/latest/command/target_link_libraries.html
As you are using the opencv library, you may want to look at the answers to this question as well: Linking Opencv in a project using cmake
Specifically, try adding these lines to your CMakeLists.txt:
find_package(OpenCV REQUIRED)
target_link_libraries(photoText.cpp ${OpenCV_LIBS})
vcpkg documentation on its CMake integration (for additional reference): https://vcpkg.io/en/docs/users/buildsystems/cmake-integration.html
Hopefully this helps!
Disclaimer: I work on the vcpkg tool.
I'm currently learning CMake and I'm trying to create my first test project. I'm able to get a simple project up and running in visual studio via CMake. However, I'm having trouble trying to add a library. I've read some guides and things but I keep getting errors. Basically, I'm trying to link SDL libraries (a game programming library) in my sample project. I've placed these libraries in a top level, 'ThirdParty' folder. Here is what my CmakeLists.txt file looks like in my top level directory:
cmake_minimum_required(VERSION 2.8.11)
project(Hello)
#Find necessary header files
find_path(SDL_INCLUDE_DIR SDL.h HINTS ${CMAKE_SOURCE_DIR}/ThirdParty/SDL2/include/)
#Find necessary library files
find_library(SDL_LIB_DIR SDL2 HINTS ${CMAKE_SOURCE_DIR}/ThirdParty/SDL2/lib/x86)
find_library(SDLMAIN_LIB_DIR SDLmain HINTS ${CMAKE_SOURCE_DIR}/ThirdParty/SDL2/lib/x86)
#Add/Link files to project
include_directories(${SDL_INCLUDE_DIR})
target_link_libraries(Test PUBLIC ${SDL_LIB_DIR})
target_link_libraries(Test PUBLIC ${SDLMAIN_LIB_DIR})
add_executable(Test "${CMAKE_SOURCE_DIR}/Source/Main.cpp")
I'm not 100 percent sure of the HINTS parameter, but I saw it used on another thread. Anyway, here's the error I keep getting:
CMake Error: The following variables are used in this project, but they are set to NOTFOUND.
Please set them or make sure they are set and tested correctly in the CMake files:
SDLMAIN_LIB_DIR
linked by target "Test" in directory C:/Users/Jason/Desktop/Test
What am I doing wrong and how do I properly link libraries in CMake?
In cmake, you first create the executable, and then you link it to a library
You have to understand how finding libraries and packages works in CMake. Typically the way it works is that you use find_library or find_package, and then cmake will set some variables that you can use to link to/use the library.
I'm not familiar with SDL, but by googling a little bit about it, I would say this is how it should look like:
find_file(SDL2_INCLUDE_DIR NAME SDL.h HINTS SDL2)
find_library(SDL2_LIBRARY NAME SDL2)
add_executable(MyExec main.cpp)
target_include_directories(MyExec ${SDL2_INCLUDE_DIR})
target_link_libraries(MyExec ${SDL2_LIBRARY})
That find_library will set the variables SDL2_INCLUDE_DIR and SDL2_LIBRARY, which you can use to link to SDL and add its includes to your project.
I am trying to compile a piece of C++ code on a server with CentOS. I need to include a library (NLopt) that is installed as a module at the location "/services/tools". I have tried "module load NLopt", but CMake does still not find the library.
What do I need to do to make CMake find the package?
"By default, [it] installs the NLopt static library (libnlopt.a) in /usr/local/lib and the NLopt header file (nlopt.h) in /usr/local/include, as well manual pages and a few other files."
So, you can include the header as
include_directories("/usr/local/include")
and link the library as
target_link_libraries(project "/usr/local/lib/lbnlopt.a")
Ideally you could try to find a CMake find module for the library.
Assuming your libraries are in /service/tools/lib and the headers in /service/tools/include, you can also set CMAKE_PREFIX_PATH, like this:
list(APPEND CMAKE_PREFIX_PATH /service/tools)
Boost header files are on /usr/include/boost.
In CMakeLists.txt I include the folder with include_directories
include_directories(/usr/include /usr/include/boost/
/usr/include/boost/smart_ptr)
However, cmake insists in not finding header files. The problem arises in intrusive_ptr.hpp, which includes #include <boost/smart_ptr/intrusive_ptr.hpp:
boost/smart_ptr/intrusive_ptr.hpp: No such file or directory
/usr/include/boost/intrusive_ptr.hpp
My guess is it does not like boost/smart_ptr/ prefix.
So, include_directories did not work.
CMake Error:
CMake Error at /usr/local/share/cmake-3.3/Modules/FindBoost.cmake:1245
(message):
Unable to find the requested Boost libraries.
Unable to find the Boost header files. Please set BOOST_ROOT to the root
directory containing Boost or BOOST_INCLUDEDIR to the directory containing
Boost's headers.
What should I do?
Thanks.
While I do not know what failed in your case, I'd recommend to simply use find_package with the included FindBoost.cmake file:
find_package(Boost REQUIRED)
include_directories(${Boost_INCLUDE_DIRS})
Done
I think you are using 3.3 cmake version, which support target_include_directories.
Even target_link_library should help here which gives the include path free if we link the library.
How do you add boost libraries in CMakeLists.txt
I am building my project for Visual Studio with CMake. I used this lines in my CMakeList.txt to include FFTW3.
find_library(FFTW_LIBRARY
NAMES fftw3 fftw)
set(FFTW_LIBRARIES "${FFTW_LIBRARY}")
I got this error from CMake:
CMake Error: The following variables are used in this project, but they are set to NOTFOUND.
Please set them or make sure they are set and tested correctly in the CMake files:
FFTW_LIBRARY
linked by target "windows_SHT" in directory C:/...
I think I did not install fftw properly. I got .dll .lib and .h files in a folder but I don't know how to explain to CMake where is the library.
Specify additional paths for find_library to use.
See: http://www.cmake.org/cmake/help/v2.8.11/cmake.html#command:find_library
You will need to include the path to your custom FFTW installation.
A similar technique will need to be used when you use find_file to locate the headers
http://www.cmake.org/cmake/help/v2.8.11/cmake.html#command:find_file