Hydro: Unable to subscribe to topic : installation or coding ? [closed]

edit

First check this on your callback arguments (see the ConstPtr&)

void chatterCallback(const std_msgs::String::ConstPtr& msg)
{
   ROS_INFO("I heard: [%s]", msg->data.c_str());
}

Then, if that doesn't work, use ros::Subscriber sub = n.subscribe("chatter", 1000, chatterCallback); instead of just invoke the method 'subscribe'

This is from subscriber/publisher tutorial:

/**
   * The subscribe() call is how you tell ROS that you want to receive messages
   * on a given topic.  This invokes a call to the ROS
   * master node, which keeps a registry of who is publishing and who
   * is subscribing.  Messages are passed to a callback function, here
   * called chatterCallback.  subscribe() returns a Subscriber object that you
   * must hold on to until you want to unsubscribe.  When all copies of the Subscriber
   * object go out of scope, this callback will automatically be unsubscribed from
   * this topic.
   *
   * The second parameter to the subscribe() function is the size of the message
   * queue.  If messages are arriving faster than they are being processed, this
   * is the number of messages that will be buffered up before beginning to throw
   * away the oldest ones.
   */