BRESENHEM CIRCLE DRAWING PROGRAM IN C

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

void main()
{
  int gd=DETECT,gm;
  int r,x,y,p,xc=320,yc=240;
  initgraph(&gd,&gm,"c:\TC\BGI");
  cleardevice();
  printf("Enter the radius :");
  scanf("%d",&r);
  x=0;
  y=r;
  putpixel(xc+x,yc-y,1);
  p=3-(2*r);
  for(x=0;x<=y;x++)
  {
    if(p<0)
    {
      y=y;
      p=(p+(4*6)+6);
    }
    else
    {
      y=y-1;
      p=p+(4*(x-y)+10);
    }
    putpixel(xc+x,yc-y,4);
    putpixel(xc-x,yc-y,4);
    putpixel(xc+x,yc+y,4);
    putpixel(xc-x,yc+y,4);
    putpixel(xc+y,yc-x,4);
    putpixel(xc-y,yc-x,4);
    putpixel(xc+y,yc+x,4);
    putpixel(xc-y,yc+x,4);
  }
  getch();
  closegraph();
}