bresenham circle c

/* Program to implement Bresenhams line generation algorithm */

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

// method that plots the circle points in all the 8 quadrants
void drawcircle(int xc, int yc, int x,int y)
{
    putpixel(xc+x,yc+y,5);       //quad 1
    putpixel(xc+y,yc+x,6);       //quad 2
    putpixel(xc-x,yc+y,5);       //quad 3
    putpixel(xc-y,yc+x,6);       //quad 4
    putpixel(xc-x,yc-y,5);       //quad 5
    putpixel(xc-y,yc-x,6);       //quad 6
    putpixel(xc+x,yc-y,5);       //quad 7
    putpixel(xc+y,yc-x,6);       //quad 8
}

// function that calculates the points of the circle to be plotted
// inputs are the the center co-ordinates and value of the radius
void bresenhemCircle(int xc, int yc, int radius){

    // x, y are used to store the new points of the circle
    // parameter decides whether a point is inside , outside or on the circle
    int x, y, parameter;

    // initial values for x, y, parameter
    x=0;
    y=radius;
    parameter = 3-2*radius;

    // plot the initial point
    drawcircle(xc,yc,x,y);

    while(x<y)
    {
        // parameter is less than 0 hence point is inside the circle so we increase the value of x
        if(parameter<0)
        {
            parameter=parameter+4*x+6;
            x++;
        }
        // parameter is 0 or greater than 0
        // so we increase both values of x and y
        else
        {
            parameter=parameter+4*(x-y)+10;
            x++;
            y--;

        }
        drawcircle(xc,yc,x,y);
        delay(10);

    }
}
void main()
{
    int gd=0,gm, i = 50;

    initgraph(&gd,&gm,"C:\\TC\\BGI");
    // circle with center (320, 240) and radius = 150
    bresenhemCircle(320, 240, 150);

    while(i < 100){
        bresenhemCircle(320, 240, i);
        i += 5;
    }
    getch();
}