ROS fuerte - check subscriber

edit

Well, thats a bit misleading in the documentation you linked.

ros::NodeHandle cannot be converted to bool, ros::Subscriber can and the conversion returns true, i. e. 1, if the subscriber is valid:

http://docs.ros.org/api/roscpp/html/c... http://docs.ros.org/api/roscpp/html/s...

In your case it'd be:

ros::NodeHandle n;
/* ... */
intruder_sub[i]=n.subscribe(topicname.c_str(), 0,Intruder_StateCallBack);
if( intruder_sub[i] ){
    cout << "cant subscribe to " << topicname << endl;
    assert(false);
}

In the docu you linked ( http://docs.ros.org/api/roscpp/html/c... ) it'd be clearer to understand if it were:

if (sub)
{
...
}

Maybe someone should open a ticket to update that....