怎样用C语言画圆？

说简单点谢谢

答案：
#include <math.h>
#include <graphics.h>            /*预定义库函数*/
void circlePoint(int x,int y)    /*八分法画圆程序*/
{
  circle(320+x*20,240+y*20,3);
  circle(320+y*20,240+x*20,3);
  circle(320-y*20,240+x*20,3);
  circle(320-x*20,240+y*20,3);
  circle(320-x*20,240+y*20,3);
  circle(320-x*20,240-y*20,3);
  circle(320-y*20,240-x*20,3);
  circle(320+y*20,240-x*20,3);
  circle(320+x*20,240-y*20,3);
}
void MidBresenhamcircle(int r)  /* 中点Bresenham算法画圆的程序 */
{
  int x,y,d;
  x=0;y=r;d=1-r;                /* 计算初始值 */
  while(x<y)
   { circlePoint(x,y);          /* 绘制点(x,y)及其在八分圆中的另外7个对称点 */
     if(d<0)  d+=2*x+3;         /* 根据误差项d的判断,决定非最大位移方向上是走还是不走 */
       else
            { d+=2*(x-y)+5;
              y--;
             }
              x++;
     delay(900000);
     }  /* while */
}
main()
{
  int i,j,r,graphmode,graphdriver;
  detectgraph(&graphdriver,&graphmode);
  initgraph(&graphdriver,&graphmode," ");
    printf("中点Bresenhamcircle算法画圆的程序\n");     /*提示信息*/
    printf("注意 |r|<=11");
    printf("\n输入半径值 r:");
    scanf("%d",&r);
  printf("按任意键显示图形...");
  getch();
  cleardevice();
  setbkcolor(BLACK);
  for(i=20;i<=620;i+=20)           /*使用双循环画点函数画出表格中的纵坐标*/
    for(j=20;j<=460;j++)
 putpixel(i,j,2);
  for(j=20;j<=460;j+=20)     &n欢迎光临学网,收藏本篇文章 [1] [2] 


$False$ 

bsp;     /*使用双循环画点函数画出表格中的横坐标*/
    for(i=20;i<=620;i++)
 putpixel(i,j,2);
  outtextxy(320,245,"0");                                     /*原点坐标*/
  outtextxy(320-5*20,245,"-5");circle(320-5*20,240,2);        /*横坐标值*/
  outtextxy(320+5*20,245,"5");circle(320+5*20,240,2);
  outtextxy(320-10*20,245,"-10");circle(320-10*20,240,2);
  outtextxy(320+10*20,245,"10");circle(320+10*20,240,2);
  outtextxy(320-15*20,245,"-15");circle(320-15*20,240,2);
  outtextxy(320+15*20,245,"15");circle(320+15*20,240,2);
  outtextxy(320,240-5*20,"-5");circle(320,240-5*20,2);        /*纵坐标值*/
  outtextxy(320,240+5*20,"5");circle(320,240+5*20,2);
  outtextxy(320,240-10*20,"-10");circle(320,240-10*20,2);
  outtextxy(320,240+10*20,"10");circle(320,240+10*20,2);
    outtextxy(20,10,"The center of the circle is (0,0) ");    /*坐标轴左上角显示提示信息*/
    setcolor(RED);                 /*标记坐标轴*/
    line(20,240,620,240);   outtextxy(320+15*20,230,"X");
    line(320,20,320,460);   outtextxy(330,20,"Y");
  setcolor(YELLOW);
  MidBresenhamcircle(r);
  setcolor(BLUE);         /*绘制圆*/
  circle(320,240,r*20);
    setcolor(2);
  getch();
  closegraph();
}
使用windows api创建一个窗口，然后调用Ellipse
用搞这么罗嗦吗？晕，我这个精简点
#include<stdio.h>
#include<math.h>
main()
{
 double y;
 int x,m;
 for(y=10;y>=-10;y--)
 {
  m=2.5*sqrt(100-y*y);
  for(x=1;x<50-m;x++)
   printf(" ");
  printf("*");
  for(;x<50+m;x++)
   printf(" ");
   printf("*\n");
 }
}

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