undefined Reference to ros::init on kinetic in non-ros-domain workspace
Hi All,
I am trying to compile a .cpp file which uses some of the ROS library functions like "ros/ros.h" , "std_msgs/String.h". In the make file , I have included the path for the respective include files in the include section.
But when I am compiling the .cpp , I am getting errors like
Undefined reference to 'ros::init(int&, char**, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>> const&, unsigned int)'.
Like wise I am getting some other errors like
:Undefined reference to ros::NodeHandle
:Undefined reference to ros::Rate::Rate(double)
:Undefined reference to ros::ok()
etc.
What could be the reason for such errors? can I get some suggestion to overcome these errors?
Thank you for your suggestion in advance?
"Undefined reference" is probably a linker error. You don't just need to add directories for searching for headers, you also need to add directories for the linker to search in (
-L), and you need to specify which libraries to search in when linking (-l).This is partially why tools like CMake/catkin exist - writing a Makefile for complex projects can be tough. It might help if we could see your Makefile or your compile command.
Hello @jarvisscchultz But I could not figure out which exact libraries are being used while I am creating .cpp file as a node in a ros package in catkin_ws.
It uses std_msgs and roscpp in the find_package() section of CMakeLists.txt. Is there any way to find out the libs used by the created ros package in the catkin_ws.
Not sure I understand your question.
find_packageonly creates variables that can be used later. For example, if youfind_packagestd_msgsandroscppthen you would be able to usetarget_link_librarieswith thecatkin_LIBRARIESvariable to link against all libs found infind_packageAgain, it would be helpful to actually see your Makefile. One other thought that might help is using
lddto test what libraries are dynamically loaded when running an executable. E.g.ldd /home/user/catkin_ws/devel/lib/package_name/executable_nameThank you so much @jarvisschultz. ldd command really helped me a lot. I could able to run my .cpp ros program outside of catkin_ workspace. I was struggling for last 2 weeks.