void sprintf_comma(char *buf, char *fmt, ...)
{

     register long i, r, flag, len;
     va_list args;

     va_start(args, fmt);
     vsprintf(buf, fmt, args);
     va_end(args);

     for (len = i = strlen(buf), flag = 0; i >= 0; i--)
     {
	if (buf[i] >= '0' && buf[i] <= '9')
	{
	   if (++flag > 3)
	   {
	      flag = 1;
	      for (r = ++len; r > i; r--)
		 buf[r] = buf[r - 1];
	      buf[i + 1] = ',';
	   }
	}
     }
}