#include<stdio.h>

#include<stdlib.h>

#include<graphics.h>

#include<math.h>

void MidBrehansemCircle(int x, int y, int radius);

int main()

{

    int gdriver = DETECT, gmove;

    int x, y, radius;

    printf("Please input circle corner:\n");

    scanf("%d%d", &x, &y);

    printf("Please input circle radius:\n");

    scanf("%d", &radius);

    initgraph(&gdriver, &gmove, "");

    MidBrehansemCircle(x, y, radius);

    system("pause");

    closegraph();

    return 0;

}

void MidBrehansemCircle(int x, int y, int radius)

{

    int d0 = 1-radius, di,x0=0,y0=radius;

    di = d0;

    while (x0<=y0)

    {

        putpixel(x0+x, y0+y, RED);      //45-90

        putpixel(y0+y, x0+x, YELLOW);   //0-45

        putpixel(x-x0, y0 + y, BLUE);   //90-135

        putpixel( y- y0, x+x0, WHITE);  //135-180

        putpixel( x- x0,  y- y0, RED);  //225-270

        putpixel( y- y0,  x- x0, YELLOW);//180-225

        putpixel(x0+x,  y- y0, BLUE);   //270-315

        putpixel(y0+y,  x- x0, WHITE);  //315-360

        if (di >= 0)

        {

            di += 2 * (x0 - y0) + 5;

            y0--;

        }

        else

            di += 2 * x0 + 3;

        x0++;

    }

}

中点Brehensam画圆算法