I am trying to build this program https://github.com/ros-controls/ros_control/wiki/hardware_interface

libarmlib.h

  #ifndef LIBARMLIB_H
    #define LIBARMLIB_H

    #include <hardware_interface/joint_command_interface.h>
    #include <hardware_interface/joint_state_interface.h>
    #include <hardware_interface/robot_hw.h>

   class MyRobot : public hardware_interface::RobotHW
   {
   public:
     MyRobot() 
    { 
      // connect and register the joint state interface
      hardware_interface::JointStateHandle state_handle_a("joint1", &pos[0], &vel[0], &eff[0]);
      jnt_state_interface.registerHandle(state_handle_a);


      registerInterface(&jnt_state_interface);

      // connect and register the joint position interface
      hardware_interface::JointHandle pos_handle_a(jnt_state_interface.getHandle("joint1"), &cmd[0]);
      jnt_pos_interface.registerHandle(pos_handle_a);



      registerInterface(&jnt_pos_interface);
     }

   private:
     hardware_interface::JointStateInterface jnt_state_interface;
     hardware_interface::PositionJointInterface jnt_pos_interface;
     double cmd[1];
     double pos[1];
     double vel[1];
     double eff[1];
   };

   #endif

program1.cpp

#include <controller_manager/controller_manager.h>
#include <iostream>
#include <iomanip>
#include "libarmlib.h"

int main()
{


  MyRobot robot;
  controller_manager::ControllerManager cm(&robot);

  while (true)
  {
     robot.read();
     cm.update(robot.get_time(), robot.get_period());
     robot.write();
     sleep();
  }
}

Cmakelists.txt

   cmake_minimum_required(VERSION 2.8.3)
  project(armbot_description)


  find_package(catkin REQUIRED COMPONENTS
    hardware_interface
    controller_manager
    joint_limits_interface
    roscpp
  )

  add_library(armlib4 src/libarmlib.h)
  target_link_libraries(armlib4 ${catkin_LIBRARIES})
  set_target_properties(armlib4 PROPERTIES LINKER_LANGUAGE CXX)

  catkin_package(
    INCLUDE_DIRS include
    LIBRARIES armlib4
    CATKIN_DEPENDS 
      controller_manager
      hardware_interface
      joint_limits_interface
      roscpp
    DEPENDS Boost
  )

  include_directories(
    include
    ${catkin_INCLUDE_DIRS}
  )

  add_executable(armbot_description src/program1.cpp)
  target_link_libraries(armbot_description armlib4)

  install(TARGETS armlib4
          LIBRARY DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION})

and I get this:

Base path: /home/sofia/catkin_ws
Source space: /home/sofia/catkin_ws/src
Build space: /home/sofia/catkin_ws/build
Devel space: /home/sofia/catkin_ws/devel
Install space: /home/sofia/catkin_ws/install
####
#### Running command: "make cmake_check_build_system" in "/home/sofia/catkin_ws/build"
####
####
#### Running command: "make -j2 -l2" in "/home/sofia/catkin_ws/build/armbot_description"
####
[  0%] Built target armlib4
[100%] Building CXX object armbot_description/CMakeFiles/armbot_description.dir/src/program1.cpp.o
/home/sofia/catkin_ws/src/armbot_description/src/program1.cpp: In function ‘int main()’:
/home/sofia/catkin_ws/src/armbot_description/src/program1.cpp:15:12: error: ‘class MyRobot’ has no member named ‘read’
      robot.read();
            ^
/home/sofia/catkin_ws/src/armbot_description/src/program1.cpp:16:22: error: ‘class MyRobot’ has no member named ‘get_time’
      cm.update(robot.get_time(), robot.get_period());
                      ^
/home/sofia/catkin_ws/src/armbot_description/src/program1.cpp:16:40: error: ‘class MyRobot’ has no member named ‘get_period’
      cm.update(robot.get_time(), robot.get_period());
                                        ^
/home/sofia/catkin_ws/src/armbot_description/src/program1.cpp:17:12: error: ‘class MyRobot’ has no member named ‘write’
      robot.write();
            ^
/home/sofia/catkin_ws/src/armbot_description/src/program1.cpp:18:12: error: too few arguments to function ‘unsigned int sleep(unsigned int)’
      sleep();
            ^
In file included from /usr/include/boost/config/stdlib/libstdcpp3.hpp:77:0,
                 from /usr/include/boost/config.hpp:44,
                 from /usr/include/boost/smart_ptr/shared_ptr.hpp:17,
                 from /usr/include/boost/shared_ptr.hpp:17,
                 from /opt/ros/indigo/include/ros/forwards.h:37,
                 from /opt/ros/indigo/include/ros/node_handle.h:31,
                 from /opt/ros/indigo/include/controller_interface/controller_base.h:36,
                 from /opt/ros/indigo/include/controller_manager/controller_spec.h:41,
                 from /opt/ros/indigo/include/controller_manager/controller_manager.h:36,
                 from /home/sofia/catkin_ws/src/armbot_description/src/program1.cpp:1:
/usr/include/unistd.h:444:21: note: declared here
 extern unsigned int sleep (unsigned int __seconds);
                     ^
make[2]: *** [armbot_description/CMakeFiles/armbot_description.dir/src/program1.cpp.o] Error 1
make[1]: *** [armbot_description/CMakeFiles/armbot_description.dir/all] Error 2
make: *** [all] Error 2
Invoking "make -j2 -l2" failed