怎样用C语言画圆？

#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=0y=rd=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=20i<=620i+=20) /*使用双循环画点函数画出表格中的纵坐标*/

for(j=20j<=460j++)

putpixel(i,j,2)

for(j=20j<=460j+=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=20i<=620i++)

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java画圆要用到绘图类Graphics，下面是实例代码和运行效果：

package com.dikea.demo01

import java.awt.*

import javax.swing.*

// java绘图原理

public class demo_01  extends JFrame {

MyPanel mp = null

public static void main(String[] args) {

// TODO 自动生成的方法存根

demo_01 demo01 = new demo_01()

}

public demo_01(){

mp = new MyPanel()

this.add(mp)

this.setSize(400, 300)

this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE)

this.setVisible(true)

}

}

// 定义一个MyPanel面板，用于绘图区域

class MyPanel extends JPanel{

//覆盖JPanel

// Graphics 是绘图的重要类，可以理解成一支画笔

public void paint(Graphics g){

//  1. 调用父类函数完成初始化任务

//  这句话不可以少

super.paint(g)

// 先画出一个圆圈

g.drawOval(100, 100, 30, 30)

}

}

代码复制进ide编程工具，运行效果如下：

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