/* A version of array_path.cpp that uses a struct Point to store the each 
   point, instead of separately storing the x and y coordinates.  Note the 
   syntax for using an array of structs.  Also, the function path_length
   is simpler in this version, since it doesn't have to refer to the x and
   y coordinates explicitly.
*/

#include<iostream.h>
#include<fstream.h>
#include<math.h>

const int NUM_POINTS = 10;

struct Point{
  public:
    double x_coord, y_coord;
};

double line_seg_length (Point, Point);
double path_length(Point[]);

void main(){

  ifstream infile("points.dat");

  Point pts[NUM_POINTS];

  for (int i = 0; i< NUM_POINTS; i++)
    infile >> pts[i].x_coord >> pts[i].y_coord;

  cout << "The length of the connect-the-dots path starting at\npoint 0"
       << " and ending at point " << NUM_POINTS - 1 << " is " 
       << path_length(pts) << ".\n";
}

double line_seg_length (Point pt1, Point pt2){
  return sqrt(pow(pt2.x_coord - pt1.x_coord,2) 
                  + pow(pt2.y_coord - pt1.y_coord,2));
}

double path_length (Point pts[]){

  double length = 0;

  for (int i=0; i < NUM_POINTS - 1; i++)
    length += line_seg_length(pts[i], pts[i+1]);

  return length;
}