Hi, I am using the RPLidar ROS SDK on ROS Kinetic Kame on Ubuntu 16.04. This code outputs laser scan data from the RPlidar.

include "ros/ros.h"

#include "sensor_msgs/LaserScan.h"


#define RAD2DEG(x) ((x)*180./M_PI)


void scanCallback(const sensor_msgs::LaserScan::ConstPtr& scan)
{
    int count = scan->scan_time / scan->time_increment;
    ROS_INFO("I heard a laser scan %s[%d]:", scan->header.frame_id.c_str(), count);
    ROS_INFO("angle_range, %f, %f", RAD2DEG(scan->angle_min), RAD2DEG(scan->angle_max));

    for(int i = 0; i < count; i++) {
        float degree = RAD2DEG(scan->angle_min + scan->angle_increment * i);
        ROS_INFO(": [%f, %f]", degree, scan->ranges[i]);
    }
}


int main(int argc, char **argv)
{
    ros::init(argc, argv, "rplidar_node_client");
    ros::NodeHandle n;


    ros::Subscriber sub = n.subscribe<sensor_msgs::LaserScan>("/scan", 1000, scanCallback);


    ros::spin();


    return 0;
}

So here is my question, I want to use the "scan->ranges[i])" data in my Int main for a robot I am using to avoid objects. I never programmed in ROS and C++ before so I am at a loss. I want my if statement to do something like

if(scan->ranges[i] > 1.5){ robotstop; }