Mid-point Circle Algorithm

/* Midpoint circle algorithm - Subhranath Chunder */

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

void circleMidPoint(int,int,int);
int equ(float,float,int);
void setPixel(int,int);
void setOthers(int x,int y,int xCenter,int yCenter);

void main()
{
  int x,y,radius,driver=DETECT,mode;
  clrscr();

  printf("Enter the co-ordinate of the centre: ");
  scanf("%d %d",&x,&y);
  printf("Enter the radius of the circle: ");
  scanf("%d",&radius);
  printf("<Press any key to continue>");

  initgraph(&driver,&mode,"F:\\tc\\bgi");
  circleMidPoint(x,y,radius);
  getch();
  closegraph();
}

void circleMidPoint(int xCenter,int yCenter,int radius)
{
  int x=0,y=radius;
  setOthers(x,y,xCenter,yCenter);
  while(x<y)
  {
     ++x;
     if( equ(x,y-(float)1/2,radius) >=0 )
        --y;
     setOthers(x,y,xCenter,yCenter);
  }
}

int equ(float x,float y,int r)
{
  int res;
  if( pow(x,2)+pow(y,2)-pow(r,2) == 0)
     res=0;
  else if( pow(x,2)+pow(y,2)-pow(r,2) < 0)
     res=-1;
  else if( pow(x,2)+pow(y,2)-pow(r,2) > 0)
     res=1;
  return res;
}

void setOthers(int x,int y,int xCenter,int yCenter)
{
  setPixel(xCenter+x,yCenter+y);
  setPixel(xCenter-x,yCenter+y);
  setPixel(xCenter+x,yCenter-y);
  setPixel(xCenter-x,yCenter-y);
  setPixel(xCenter+y,yCenter+x);
  setPixel(xCenter-y,yCenter+x);
  setPixel(xCenter+y,yCenter-x);
  setPixel(xCenter-y,yCenter-x);
}

void setPixel(int x,int y)
{
  putpixel(x,y,2);
}