teleop modification

    #include <sys/poll.h>
    #include "ros/ros.h"
    #include <geometry_msgs/Twist.h>
    #define KEYCODE_W 0x77
    #define KEYCODE_X 0x78
    #define KEYCODE_E 0x65
    #define KEYCODE_C 0x63

    double max_speed = 0.500; // m/second
    double max_turn = 60.0*M_PI/180.0; // rad/second
    int kfd = 0;

    int main(int argc, char **argv)
    {
      ros::init(argc, argv, "talker");
      ros::NodeHandle n;
      ros::Publisher chatter_pub = n.advertise<geometry_msgs::Twist>("chatter", 1000);
      ros::Rate loop_rate(10);

      int count = 1;
      while (ros::ok())
        {
          geometry_msgs::Twist cmdvel;
          char c;
          int speed=0;
          int turn=0;
          bool dirty=false;
          puts("Reading from keyboard");
          puts("---------------------------");
          puts("w/x : increase/decrease max linear speed by 10%");
          puts("e/c : increase/decrease max angular speed by 10%");
          puts("---------------------------");
          puts("anything else : stop");
          puts("---------------------------");

          //Keyboard polling
          struct pollfd ufd;
          ufd.fd = kfd;
          ufd.events = POLLIN;
          for(;;)
    	{
    	  // get the next event from the keyboard
    	  int num;
    	  if((num = poll(&ufd, 1, 250)) < 0)
    	    {
    	      perror("poll():");
    	      break;
    	      //return;
    	    }
    	  else if(num > 0)
    	    {
    	      if(read(kfd, &c, 1) < 0)
    		{
    		  perror("read():");
    		  break;
    		  //  return;
    		}
    	    }
    	  else
    	    continue;

    	  switch(c)
    	    {
    	    case KEYCODE_W:
    	      max_speed += max_speed / 10.0;
    	      // if(always_command)
    	      // 	dirty = true;
    	      break;
    	    case KEYCODE_X:
    	      max_speed -= max_speed / 10.0;
    	      // if(always_command)
    	      // 	dirty = true;
    	      break;
    	    case KEYCODE_E:
    	      max_turn += max_turn / 10.0;
    	      // if(always_command)
    	      // 	dirty = true;
    	      break;
    	    case KEYCODE_C:
    	      max_turn -= max_turn / 10.0;
    	      // if(always_command)
    	      // 	dirty = true;
    	      break;
    	    default:
    	      speed = 0;
    	      turn = 0;
    	      dirty = true;
    	    }
    	  if (dirty == true)
    	    {
    	      cmdvel.linear.x = speed * max_speed;
    	      cmdvel.angular.z = turn * max_turn;

    	     chatter_pub.publish(cmdvel);
    	     //Actual information:
    	     printf("The speed information sent is: \n Linear speed x %f  \n  Angular speed z %f  \n ", cmdvel.linear.x,cmdvel.angular.z);

    	    }
    	}
          ros::spinOnce();
          loop_rate.sleep();
        }


      return 0;
    }