laser_scan position transformer

edit

this is my code, but i get just zeros i run just topic /scan, i get the real value when i run /range topic. have you any idea for this problem?

  #include <ros/ros.h>
    #include <tf/transform_broadcaster.h>
    #include <sensor_msgs/LaserScan.h>
    #include "sensor_msgs/Range.h"
    #include "std_msgs/String.h"


    double range;
    void rangeCallback(const sensor_msgs::Range::ConstPtr& range_msg)
    {   
        range = range_msg->range;
        ROS_INFO("I heard: [%f]", range);
    }

    int main(int argc, char** argv){
    ros::init(argc, argv, "range_listner");
    ros::init(argc, argv, "laser_scan_publisher");
    tf::TransformBroadcaster broadcaster;
    ros::NodeHandle n;
    ros::Subscriber sub = n.subscribe("/ultrasound", 1000, rangeCallback);
    ros::Publisher scan_pub = n.advertise<sensor_msgs::LaserScan>("scan",50);
    unsigned int num_readings = 20;
    double laser_frequency = 40;
    double ranges[num_readings];
    int count = 10;
    ros::Rate r(1.0);
    while(n.ok()){

        for(unsigned int i=0; i<num_readings; i++)
        {
            ranges[i] = range;
        }
        ros::Time scan_time = ros::Time::now();
        sensor_msgs::LaserScan scan;
        scan.header.stamp = scan_time;
        scan.header.frame_id = "base_link";
        scan.angle_min = -1.57;
        scan.angle_max = 1.57;  
        scan.angle_increment = 3.14 / num_readings;
        scan.time_increment = (1/laser_frequency)/(num_readings);
        scan.range_min = 0.0;
        scan.range_max = 100.0;
        scan.ranges.resize(num_readings);
        scan.intensities.resize(num_readings);
        for(unsigned int i=0; i<num_readings; i++)
        {
            scan.ranges[i] = ranges[i];
        }
        scan_pub.publish(scan);
        ++count;
        broadcaster.sendTransform(
                tf::StampedTransform(
                    tf::Transform(tf::Quaternion(0, 0, 0, 1), tf::Vector3(0.1, 0.0, 0.2)),
                    ros::Time::now(),"base_link", "base_laser"));
        r.sleep();
    }
    }