c 将年月日转化为星期

/*得到年月日转化为星期几*/
LOCAL ulong_t DateWeekGet(ulong_t year,ulong_t month,ulong_t day)
{
    ulong_t c = 0;
    ulong_t s = 0;
    ulong_t w = 0;
    ulong_t week_day = 0;
    if (month==1) c=day;
    else if (month==2) c=31+day;
    else if (month==3) c=31+28+day;
    else if (month==4) c=31+28+31+day;
    else if (month==5) c=31+28+31+30+day;
    else if (month==6) c=31+28+31+30+31+day;
    else if (month==7) c=31+28+31+30+31+30+day;
    else if (month==8) c=31+28+31+30+31+30+31+day;
    else if (month==9) c=31+28+31+30+31+30+31+31+day;
    else if (month==10) c=31+28+31+30+31+30+31+31+30+day;
    else if (month==11) c=31+28+31+30+31+30+31+31+30+31+day;
    else if (month==12) c=31+28+31+30+31+30+31+31+30+31+30+day;
    if (month>2)
    {
      if (year%100==0) 
      {
          if (year%400==0) 
              c=c+1;
      }    
      else if (year%4==0)
          c=c+1;
    }   
    s=(year-1)*365+(year-1)/4-(year-1)/100+(year-1)/400+c;
    w=s%7;
    if(w == 0)
    {
        week_day = 7;
    }
    else
    {
        week_day = w;
    }
    return week_day;
}

    static char *monthNames[] =
    {
        "???",
        "Jan",
        "Feb",
        "Mar",
        "Apr",
        "May",
        "Jun",
        "Jul",
        "Aug",
        "Sep",
        "Oct",
        "Nov",
        "Dec"
    };
    
    static char *weekNames[] =
    {
        "???",
        "Mon",
        "Tue",
        "Wed",
        "Thu",
        "Fri",
        "Sat",
        "Sun"
    };