NLOPT importing and using C++

Question

I have been trying on and off for the past year to import the NLopt library into my work. I have been unsuccessful, and I am desperate for help.

Here is some of my CMAKE file

cmake_minimum_required(VERSION 3.21)
project(DynamicRRT)
set(CMAKE_CXX_STANDARD 17)
set(CONAN_CMAKE_CXX_STANDARD 17)
include_directories(/opt/homebrew/Cellar/eigen/3.4.0_1/include/eigen3/)
find_library(nlopt /Users/brandon/Extern/nlopt_install/ NAMES libnlopt nlopt NLopt)
include_directories(/Users/brandon/Extern/nlopt_install/include/ )
link_directories(/Users/brandon/Extern/nlopt_install/include/ )
#INCLUDE_DIRECTORIES(/Users/brandon/CLionProjects/nlopt/)
#INCLUDE_DIRECTORIES(/opt/homebrew/Cellar/nlopt/2.7.1/include/)
#include_directories(/usr/local/include/)
#add_library(nlopt /Users/brandon/Extern/nlopt_install/include)
#add_compile_options(-Wa,-mbig-obj)¡

add_executable(DynamicRRT main.cpp  utilities.cpp utilities.h rrt_star.cpp rrt_star.h tree.cpp tree.h Nodes.cpp Nodes.h Obstacles.cpp Obstacles.h macro_rrt_star.cpp macro_rrt_star.h collisions.cpp collisions.h dynamic_rrt_star.cpp dynamic_rrt_star.h trajectory.cpp trajectory.h transformer.cpp transformer.h print_utilities.cpp print_utilities.h random_utilities.cpp random_utilities.h)# inverse_kinematics.cpp inverse_kinematics.h)# rrt_star.cpp rrt_star.h)#rrt_star_util.cpp rrt_star_util.h
target_link_libraries(DynamicRRT nlopt)

You can see that I've commented out a number of attempts at getting this imported. CMake does not throw any errors. However, if I try building the project, I get:

/Applications/CLion.app/Contents/bin/cmake/mac/bin/cmake --build /Users/brandonmeng/CLionProjects/DynamicRRT/cmake-build-default-gcc --target all -- -j 8
[ 14%] Building CXX object CMakeFiles/DynamicRRT.dir/Obstacles.cpp.o
[ 14%] Building CXX object CMakeFiles/DynamicRRT.dir/utilities.cpp.o
[ 35%] Building CXX object CMakeFiles/DynamicRRT.dir/rrt_star.cpp.o
[ 35%] Building CXX object CMakeFiles/DynamicRRT.dir/macro_rrt_star.cpp.o
[ 35%] Building CXX object CMakeFiles/DynamicRRT.dir/Nodes.cpp.o
[ 42%] Building CXX object CMakeFiles/DynamicRRT.dir/main.cpp.o
[ 50%] Building CXX object CMakeFiles/DynamicRRT.dir/tree.cpp.o
[ 57%] Building CXX object CMakeFiles/DynamicRRT.dir/collisions.cpp.o
[ 64%] Building CXX object CMakeFiles/DynamicRRT.dir/dynamic_rrt_star.cpp.o
[ 71%] Building CXX object CMakeFiles/DynamicRRT.dir/trajectory.cpp.o
[ 78%] Building CXX object CMakeFiles/DynamicRRT.dir/transformer.cpp.o
[ 85%] Building CXX object CMakeFiles/DynamicRRT.dir/print_utilities.cpp.o
[ 92%] Building CXX object CMakeFiles/DynamicRRT.dir/random_utilities.cpp.o
[100%] Linking CXX executable bin/DynamicRRT
ld: library not found for -lnlopt
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[2]: *** [bin/DynamicRRT] Error 1
make[1]: *** [CMakeFiles/DynamicRRT.dir/all] Error 2
make: *** [all] Error 2

Answer 1

link_directories(/Users/brandon/Extern/nlopt_install/include/ )

The library to link with is likely not in the include directory with the header files. It's more likely they're in a lib directory:

link_directories(/Users/brandon/Extern/nlopt_install/lib)