/* ==============  Program Description  ============= */
/*   program name : ch24_30.c                         */
/*   ball moving application.                         */
/* ================================================== */
#include  <graphics.h>
#include  <dos.h>

void main()
{
    int     driver = DETECT,mode;
    int     x = 100, y = 160, radius = 20, xdir;

    initgraph(&driver,&mode,"G:\\APPS\\BC31.WIN\\bgi");
    rectangle(79,139,521,181);
    while ( !kbhit() )
    {
       setcolor(BLACK);
       circle(x,y,radius);
       if ( x == 500 )           /* touch the rightmost */
          xdir = -4;
       else if ( x == 100 )      /* touch the leftmost  */
          xdir = 4;
       x += xdir;
       setcolor(WHITE);
       circle(x,y,radius);
       delay(50);
    }
    getch();
    closegraph();
}