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  int num=20,i;

  int top,bottom;

  initgraph(&driver,&mode,"");

  top=y-30;

  bottom=y-30;

  for(i=0;i

  {

  ellipse(250,250,0,360,top,bottom);

  top-=5;

  bottom+=5;

  }

  getch();

  }

  ==============================================================

  【程序64】

  题目：利用ellipse and rectangle 画图。

  1.程序分析：

  2.程序源代码：

  #include "stdio.h"

  #include "graphics.h"

  #include "conio.h"

  main()

  {

  int driver=VGA,mode=VGAHI;

  int i,num=15,top=50;

  int left=20,right=50;

  initgraph(&driver,&mode,"");

  for(i=0;i

  {

  ellipse(250,250,0,360,right,left);

  ellipse(250,250,0,360,20,top);

  rectangle(20-2*i,20-2*i,10*(i+2),10*(i+2));

  right+=5;

  left+=5;

  top+=10;

  }

  getch();

  }

  ==============================================================

  【程序65】

  题目：一个最优美的图案。　　　

  1.程序分析：

  2.程序源代码：

  #include "graphics.h"

  #include "math.h"

  #include "dos.h"

  #include "conio.h"

  #include "stdlib.h"

  #include "stdio.h"

  #include "stdarg.h"

  #define MAXPTS 15

  #define PI 3.1415926

  struct PTS {

  int x,y;

  };

  double AspectRatio=0.85;

  void LineToDemo(void)

  {

  struct viewporttype vp;

  struct PTS points[MAXPTS];

  int i, j, h, w, xcenter, ycenter;

  int radius, angle, step;

  double rads;

  printf(" MoveTo / LineTo Demonstration" );

  getviewsettings( &vp );

  h = vp.bottom - vp.top;

  w = vp.right - vp.left;

  xcenter = w / 2; /* Determine the center of circle */

  ycenter = h / 2;

  radius = (h - 30) / (AspectRatio * 2);

  step = 360 / MAXPTS; /* Determine # of increments */

  angle = 0; /* Begin at zero degrees */

  for( i=0 ; i

  rads = (double)angle * PI / 180.0; /* Convert angle to radians */

  points[i].x = xcenter + (int)( cos(rads) * radius );

  points[i].y = ycenter - (int)( sin(rads) * radius * AspectRatio );

  angle += step; /* Move to next increment */

  }

  circle( xcenter, ycenter, radius ); /* Draw bounding circle */

  for( i=0 ; i

  for( j=i ; j

  moveto(points[i].x, points[i].y); /* Move to beginning of cord */

  lineto(points[j].x, points[j].y); /* Draw the cord */

  } } }

  main()

  {int driver,mode;

  driver=CGA;mode=CGAC0;

  initgraph(&driver,&mode,"");

  setcolor(3);

  setbkcolor(GREEN);

  LineToDemo();}

  ==============================================================

  【程序66】

  题目：输入3个数a,b,c，按大小顺序输出。　　　

  1.程序分析：利用指针方法。

  2.程序源代码：

  /*pointer*/

  main()

  {

  int n1,n2,n3;

  int *pointer1,*pointer2,*pointer3;