128.金刚石图案

/* diamond */
#include <graphics.h>
#include <math.h>
void main()
{
  float t;
  int x0=320,y0=240;
  int n,i,j,r;
  int x[50],y[50];
  int gdriver=DETECT,gmode;
  printf("Please input n(23<=n<=31) and r(100<=r<=200):\n");
  scanf("%d%d",&n,&r);
  initgraph(&gdriver,&gmode,"c:\\tc");
  cleardevice();
  setcolor(4);
  outtextxy(80,20,"This program show the Diamond picture.");
  t=6.28318/n;
  for(i=0;i<n;i++)
  {
    x[i]=x0+r*cos(i*t);
    y[i]=y0+r*sin(i*t);
  }
  for(i=0;i<=n-2;i++)
  {
    for(j=i+1;j<=n-1;j++)
      line(x[i],y[i],x[j],y[j]);
  }
  outtextxy(80,460,"Press any key to quit...");
  getch();
  closegraph();
}