Midpoint circle drawing algorithm

/* compiler- Turbo c++ author- Mangilal Sharma =================================

Midpoint circle algorithm=================================================*/ 

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

void plotpoints(int x, int y, int cx, int cy)
{
    putpixel(cx + x, cy + y, 4);
    putpixel(cx - x, cy + y, 4);
    putpixel(cx + x, cy - y, 4);
    putpixel(cx - x, cy - y, 4);
    putpixel(cx + y, cy + x, 4);
    putpixel(cx - y, cy + x, 4);
    putpixel(cx + y, cy - x, 4);
    putpixel(cx - y, cy - x, 4);
}

void main()
{
    int cx, cy, x = 0, y, r, p;
    int gd = DETECT, gm = DETECT;

    clrscr();

    printf("Enter the center \n");
    scanf("%d%d", &cx, &cy);
    printf("Enter the radius : ");
    scanf("%d", &r);

    y = r;
    p = 1 - r;

    initgraph(&gd, &gm, "");
    cleardevice();

    while (x < y) {
    plotpoints(x, y, cx, cy);
    x++;
    if (p < 0)
        p += 2 * x + 1;
    else {
        y--;
        p += 2 * (x - y) + 1;
    }
    }

    getch();

}

/*=============================19Nov.,2010=============================*/