一个桌面闹钟源程序

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/*###############   CLOCK.C  ###############*/
/*$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$*/

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>
#include <dos.h>
#include <math.h>
#define X(a,b,c) x=a*cos(b*c*pi/180.0-pi/2)+midx;
#define Y(a,b,c) y=a*sin(b*c*pi/180.0-pi/2)+midy;
#define d(a,b,c) X(a,b,c);Y(a,b,c);line(midx,midy,x,y)
#define  pi   3.1415926

void main(void)
{
   float x,y;
   int gdriver = DETECT, gmode, errorcode;
   int midx, midy,l,x1,x2,y1,y2;
   int radius = 100;
   struct time t;
   float h,m,s;
   int i;

   /* initialize graphics  */
   initgraph(&gdriver, &gmode, " ");

   /* read result of initialization */
   errorcode = graphresult();
   if (errorcode != grOk)  /* an error occurred */
   {
      printf("Graphics error: %s\n", grapherrormsg(errorcode));
      printf("Press any key to halt:");
      getch();
      exit(1); /* terminate with an error code */
   }

   setwritemode(1);   /*she zhi wei fu gai xing shi,zuo yong shi*/
       /* mei hua yi ci xian jiou qing chu yi ci*/

   /*yi xia shi de dao yuan xi zuo biao */
   midx = getmaxx() / 2;
   midy = getmaxy() / 2;

   setbkcolor(1); /*bei jing yan se wei BLUE*/

   setcolor(2);             /*she zhi li mian circle de color*/
   circle(midx, midy, radius);   /* draw the li mian circle */
   setcolor(5);             /*she zhi wai mian circle de color*/
   circle(midx,midy,radius+5);     /*draw wai mian de circle*/
   setcolor(3);             /*she zhi yuan xin de color*/
   circle(midx, midy, 2);   /*draw the center of the circle*/

   /*the following lines are drawing the KE_DU pan */

   for(i=0;i<60;i++)
   {
     if(i%5==0) l=15;
     else l=5;

     x1=100*cos(i*6*pi/180)+midx;
     y1=100*sin(i*6*pi/180)+midy;

     x2=(100-l)*cos(i*6*pi/180)+midx;
     y2=(100-l)*sin(i*6*pi/180)+midy;

     line(x1,y1,x2,y2);
   }