#include<stdio.h>  /* 0,200,100,50*/
#include <graphics.h>
#include <conio.h>
#include <math.h>
main()
{
 int gd=DETECT,gm;
 int i,xa,ya,xb,yb,dy,dx,pa,p,xk,yk,yend;
 printf("Enter the start co-ordinate (xa,ya) :");
 scanf("%d %d",&xa,&ya);
 printf("Enter the end co-ordinate (xb,yb) :");
 scanf("%d %d",&xb,&yb);
 initgraph(&gd,&gm,"c:\\turboc\\bgi");

 putpixel(xa,ya,WHITE);

	 /* computing for the constants dx, dy */
	dx=fabs(xb-xa);
	dy=fabs(yb-ya);
	/* computing for inital value of */
	p = dy-2*(dx);
if (ya > yb)
 {
    xk = xb;
    yk = yb;
    yend = ya;
 }
 else
 {
    xk = xa;
    yk = ya;
    yend = yb;
 }
 /* main loop */
 while (yk <= yend)
 {
  if(p<0)
    {
      xk--;
      yk++;
 /* //    putpixel(xk,yk,WHITE);*/
      p=p - 2*(fabs(dx)-fabs(dy));
     }
   else
     {
      yk++;
/*//      putpixel(xk,yk,WHITE);*/
      p=(p-2*fabs(dx));
     }
     putpixel(xk,yk,RED);
 }



 getch();
 line(xa,ya,xb,yb);
 getch();
 closegraph();
 return(0);
}