Reflecting Circle Animation

#include<stdio.h>
#include<graphics.h>
#include<dos.h>
#include<conio.h>


void init_graph();
void bresenham_circle(const int,const int,const int,int);

void main( )
{
 int ho = 95;
 int ko = 55;
 int ro = 25;
 int hdo = 2;
 int kdo = 2;

 init_graph();

 do
 {
 ho += hdo;
 ko += kdo;
 cleardevice();
 if(ho <= 40 || ho >= 600)
  hdo *= -1;
 if(ko <= 10 || ko >= 470)
  kdo *= -1;
 bresenham_circle(ho,ko,ro,RED);
 delay(5);
 }while(!kbhit());
 getch();
}

void init_graph()
{
 int gdriver = DETECT, gmode, errorcode;
 initgraph(&gdriver, &gmode, "");
 errorcode = graphresult();
 if (errorcode != grOk)  /* an error occurred */
 {
   printf("Graphics error: %s\n", grapherrormsg(errorcode));
   printf("Press any key to halt:");
   getch();
 }
}



void bresenham_circle(const int h,const int k,const int r,int col)
{
 int x=0;
 int y=r;
 int p=(3-(2*r));
 do
 {
  putpixel(h+x,k+y,col);
  putpixel(h+y,k+x,col);
  putpixel(h+y,k-x,col);
  putpixel(h+x,k-y,col);
  putpixel(h-x,k-y,col);
  putpixel(h-y,k-x,col);
  putpixel(h-y,k+x,col);
  putpixel(h-x,k+y,col);
  x++;
  if(p<0)
   p+=((4*x)+6);
  else
  {
   y--;
   p+=((4*(x-y))+10);
  }
 }while(x<=y);

}