I've programmed only in Java in my career and started using C++ since 10 days, so this question may seem strange to many of you. I have defined the structure of a class in a header file:
#include "ros/ros.h" #include "nav_msgs/Odometry.h" #include "geometry_msgs/Pose.h" #include "geometry_msgs/Point.h" #include "stdio.h" #include "sensor_msgs/LaserScan.h" #include "list" #include "vector" #include "scan_node.h" #include "odom_node.h" #include "coord.h" class stage_listener{ public: stage_listener(); private: std::list odom_list; std::list scan_list; std::list corners_list; std::list polar2cart(std::vector, float, float, float, float); void addOdomNode (const nav_msgs::Odometry); void addScanNode (const sensor_msgs::LaserScan); void extractCorners(std::vector, float, float, float, float); int distance (float, float, float, float, float); void nodes2text(std::vector, std::vector); int numOdom(); int numScan(); };
In the associated .cpp file, I wrote a main:
int main(int argc, char **argv){ char buffer [1024]; while(1){ int i = fscanf(stdin,"%s",buffer); if(strcmp("exit",buffer) == 0) exit(0); else if(strcmp("num_nodes",buffer) == 0){ ROS_INFO("Odometry nodes: %i\nScan nodes: %i",numOdom(),numScan()); } else{} } }
The ROS_INFO function is part of Willow Garage's ROS and you can intend it like a normal printf, taking exactly arguments in the same form. On compiling code, I get the following:
/home/ubisum/fuerte_workspace/beginner/src/stage_listener.cpp: In function ‘int main(int, char**)’: /home/ubisum/fuerte_workspace/beginner/src/stage_listener.cpp:223:5: error: ‘numOdom’ was not declared in this scope /home/ubisum/fuerte_workspace/beginner/src/stage_listener.cpp:223:5: error: ‘numScan’ was not declared in this scope
Do you know the cause of the errors? In Java, you can access private fields/functions, so I can't understand the reason why in C++ it's not possible.
main
is a class member (or whatever the Java terminology for that is) and so can access private members of that class - but not of others. Perhaps that's what you mean? – Mike Seymourmain
is astatic
method. You'd still need to create a class instance formain
to be able to invoke its methods, unless all methods in question arestatic
as well, but clearly that's not the case here. – Praetorian