ros Getting started with ros Hello World Publisher

Example

Create a workspace

mkdir -p ~/catkin_ws/src
cd ~/catkin_ws/src
catkin_init_workspace

Build your workspace

cd ~/catkin_ws/
catkin_make

Source your setup file

source devel/setup.bash

Create a new package named hello_world with some basic dependencies

catkin_create_pkg hello_world std_msgs rospy roscpp

Navigate to your src directory and create a new file called talker.cpp

cd hello_world/src
touch talker.cpp

Edit your new file and paste this code in to publish a "hello world" message

#include "ros/ros.h"
#include "std_msgs/String.h"

#include <sstream>

int main(int argc, char **argv)
{
  ros::init(argc, argv, "talker");

  ros::NodeHandle n;

  ros::Publisher chatter_pub = n.advertise<std_msgs::String>("chatter", 1000);

  ros::Rate loop_rate(10);

  int count = 0;
  while (ros::ok())
  {
    std_msgs::String msg;

    std::stringstream ss;
    ss << "hello world " << count;
    msg.data = ss.str();

    ROS_INFO("%s", msg.data.c_str());

    chatter_pub.publish(msg);

    ros::spinOnce();

    loop_rate.sleep();
    ++count;
  }

  return 0;
}

Return to the root of your package directory

cd ..

Add/uncomment these lines to your CMakeLists.txt

catkin_package(
 INCLUDE_DIRS include
 LIBRARIES hello_world
#  CATKIN_DEPENDS roscpp rospy std_msgs
#  DEPENDS system_lib
)

include_directories(include ${catkin_INCLUDE_DIRS})

add_executable(talker src/talker.cpp)
target_link_libraries(talker ${catkin_LIBRARIES})
add_dependencies(talker hello_world_generate_messages_cpp)

Return to the root of your workspace

cd ..

Build your new publisher

catkin_make  

Source your setup file again so that you have the new package and publisher

source devel/setup.bash

Start ROS

roscore

Leave roscore running and in a new terminal tab/window, start your publisher

rosrun hello_world talker

Leave the publisher running and in ANOTHER new terminal tab/window, echo the output

rostopic echo /chatter