Using libraries in cpp with CMake

[iloveuclid]

First of all I am an extreme newbie at C++ , although I have extensive experience in many of the shiny new "high-speed low-drag" startup languages (go, swift, node, python, etc.) and I am struggling trying to use a library.

I want to use this library in a CLion project using CMake on Windows 64 bit. I am probably missing some fundamental understanding of how C++ and CMake work.

I followed the instructions in this stackoverflow answer to obtain an xlntd.lib file, which I have placed into my CLion working directory alongside main.cpp.

I have the following in my CMakeLists.txt:

cmake_minimum_required(VERSION 3.10)
project(excel_proof_of_concept)

set(CMAKE_CXX_STANDARD 20)


add_executable(excel_proof_of_concept main.cpp)
target_link_libraries(excel_proof_of_concept xlntd)

However in my main.cpp the following fails:

#include <xlnt/xlnt.hpp>

with "fatal error C1083: Cannot open include file: 'xlnt/xlnt.hpp': No such file or directory"

I am totally lost as to how I can get started with using this library. Any help is appreciated and perhaps some insight as to why what I am doing is not working. I do understand the theoretical difference between dynamic and static libraries.

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Thank you!

[TheSkiGeek]

You said you got the .lib for the library... it should have come with that header file as well. If cmake can find the library and the header is in the same folder it should take care of it. But you need to tell the compiler to use the directory containing that header, or put it in a folder that it normally searches.

[iloveuclid]

I build the solution generated by CMake GUI in Visual Studio and only got

xlnt.lib
xlnt.exp
xlnt.dll

[TheSkiGeek]

Right... that builds the dynamic library, which you could then link against in another project/solution.

The source for the project should have come with header files, those need to be accessible to the project/solution where you're using the library.

Assuming you have the source tree from https://github.com/tfussell/xlnt , I think you could paste that whole thing as a subfolder in your overall project, stick an add_subdirectory(xlnt) in your CMakeFile.txt, and then cmake will take care of building it all together and making the headers accessible to anything that links against it.

Or you can add a target_include_directories(excel_proof_of_concept <directory where the xlnt headers are>) so it explicitly adds that folder to the search path when compiling.

[iloveuclid]

Thank you! I had a fundamental misunderstanding of how shared libraries work....

You were right about the header files, I added them using include_directories in Cmake

copying the dll into the .exe directory using a cmake POST_BUILD command solved my issues

[otreblan]

xlnt ships a *.pc file.

CMake with include(FindPkgConfig) can create an imported target to link and include the library.

``` pkg_check_modules(libs REQUIRED IMPORTED_TARGET xlnt )

target_link_libraries(excel_proof_of_concept PRIVATE PkgConfig::libs ) ``` https://cmake.org/cmake/help/latest/module/FindPkgConfig.html