自学教程：C++ year函数代码示例

    void Date::add_month (int n) {        // Negative        if(n < 0)        {            int tmp = month();            this->m = tmp - abs(n) > 0 ? tmp - abs(n) : 12 - abs(n + tmp) % 12;            if(n + tmp <= 0) {                this->y -= (1 + floor(abs(n + tmp)/12));            }        } else {            int months = abs(n) + month();            if(months % 12 != 0)                this->m = months % 12;            else                this->m = 12;            if(months > 12 && months % 12 != 0) {                this->y += months / 12;            } else if (months > 12) {                this->y += months / 12 - 1;            }        }        if(!valid_date(year(), month(), day())) {            this->d = days_this_month();        }        this->julian_day_number = calc_julian_day_number(year(), month(), day());    }

 void Date::add_year (int n) {     this->y += n;     if(!valid_date(year(), month(), day())) {         this->d = days_this_month();     }     this->julian_day_number = calc_julian_day_number(year(), month(), day()); }

    Middle& Middle::add_year(int n) {        if(n == 0) return *this;        int sign = -1;        if( n > 0)  {            sign = 1;        }        if(isLeapYear()) {            if(std::abs(n) > 3 && isLeapYear(year() + 4*sign)) {                _numeric += (365*4 + 1 )*sign;                n -= sign * 4;                return add_year(n);            }else if((sign > 0 && (month() < 3 && !(month() == 2 && day() == 29 ))) ||                    (sign < 0 && (month() > 2 ||  (month() == 2 && day() == 29 )))) {                _numeric += 366 * sign;                n -= sign;                return add_year(n);            }        } else if(isLeapYear(year() + sign) &&                ((( month() > 2  ||  (month() == 2 && day() == 29 ))&& sign > 0) ||                    (sign < 0 && (month() < 3  && !(month() == 2 && day() == 29 ))))) {            _numeric += 366 * sign;            n -= sign;            return add_year(n);        }        _numeric += 365 * sign;        n -= sign;        return add_year(n);    }

// This method MUST be re-implemented in any new Calendar Systembool KCalendarSystem::isValid( int y, int month, int day ) const{    // Default to true Gregorian    if ( y < year( earliestValidDate() ) || y > year( latestValidDate() ) ) {        return false;    }    if ( month < 1 || month > 12 ) {        return false;    }    if ( month == 2 ) {        if ( isLeapYear( y ) ) {            return ( day >= 1 && day <= 29 );        } else {            return ( day >= 1 && day <= 28 );        }    }    if ( month == 4 || month == 6 || month == 9 || month == 11  ) {        return ( day >= 1 && day <= 30 );    }    return ( day >= 1 && day <= 31 );}

//日期/时间字符串//length对于年份，=2则为短格式（如2004年则返回"04"），其余//数值则为4位字符串//对于其他日期/时间，=2则为固定两位字符串，（如1返回"01"，//29返回"29"），其余数值则根据具体日期/时间返回1或2位字符串//因此只有length=2的情况才会有相应操作，其余均采用默认操作。LPCTSTR ringDateTime::year2str(int length/*=0*/){	if(length == 2)		return formatStr(m_str,year()%100,length);	else		return formatStr(m_str,year(),0);}

// Okint KCalendarSystemHebrew::daysInYear(const TQDate & date) const{  TQDate first, last;  setYMD(first, year(date), 1, 1); // 1 Tishrey  setYMD(last, year(date) + 1, 1, 1); // 1 Tishrey the year later  return first.daysTo(last);}

 BOOST_FORCEINLINE Date operator >(month_day md, Date d) {   Date res;   if (res.set_if_valid_date(year(d),month(md),day(md)) &&  res > d ) return res;   if (res.set_if_valid_date(year(year(d)+1),month(md),day(md)) &&  res > d ) return res;   res=Date(year(year(d)+2),month(md),day(md));   return res; }

/*----------------------------------------------------------------------* * Determine whether the given Local time_t is within the DST interval  * * or the Standard time interval.                                       * *----------------------------------------------------------------------*/boolean Timezone::locIsDST(time_t local){    //recalculate the time change points if needed    if (year(local) != year(_dstLoc)) calcTimeChanges(year(local));    if (_stdLoc > _dstLoc)    //northern hemisphere        return (local >= _dstLoc && local < _stdLoc);    else                      //southern hemisphere        return !(local >= _stdLoc && local < _dstLoc);}

/*----------------------------------------------------------------------* * Convert the given UTC time to local time, standard or                * * daylight time, as appropriate.                                       * *----------------------------------------------------------------------*/time_t Timezone::toLocal(time_t utc){    //recalculate the time change points if needed    if (year(utc) != year(_dstUTC)) calcTimeChanges(year(utc));    if (utcIsDST(utc))        return utc + _dst.offset * SECS_PER_MIN;    else        return utc + _std.offset * SECS_PER_MIN;}

/*----------------------------------------------------------------------* * Convert the given local time to UTC time.                            * *                                                                      * * WARNING:                                                             * * This function is provided for completeness, but should seldom be     * * needed and should be used sparingly and carefully.                   * *                                                                      * * Ambiguous situations occur after the Standard-to-DST and the         * * DST-to-Standard time transitions. When changing to DST, there is     * * one hour of local time that does not exist, since the clock moves    * * forward one hour. Similarly, when changing to standard time, there   * * is one hour of local times that occur twice since the clock moves    * * back one hour.                                                       * *                                                                      * * This function does not test whether it is passed an erroneous time   * * value during the Local -> DST transition that does not exist.        * * If passed such a time, an incorrect UTC time value will be returned. * *                                                                      * * If passed a local time value during the DST -> Local transition      * * that occurs twice, it will be treated as the earlier time, i.e.      * * the time that occurs before the transistion.                         * *                                                                      * * Calling this function with local times during a transition interval  * * should be avoided!                                                   * *----------------------------------------------------------------------*/time_t Timezone::toUTC(time_t local){    //recalculate the time change points if needed    if (year(local) != year(_dstLoc)) calcTimeChanges(year(local));    if (locIsDST(local))        return local - _dst.offset * SECS_PER_MIN;    else        return local - _std.offset * SECS_PER_MIN;}

/*----------------------------------------------------------------------* * Determine whether the given UTC time_t is within the DST interval    * * or the Standard time interval.                                       * *----------------------------------------------------------------------*/boolean Timezone::utcIsDST(time_t utc){    //recalculate the time change points if needed    if (year(utc) != year(_dstUTC)) calcTimeChanges(year(utc));    if (_stdUTC > _dstUTC)    //northern hemisphere        return (utc >= _dstUTC && utc < _stdUTC);    else                      //southern hemisphere        return !(utc >= _stdUTC && utc < _dstUTC);}

void ContentStructuredDocument::parseDate(const string& dateStr,                                  QDate& dateBegin,                                  QDate& dateEnd){  dateBegin=QDate();  dateEnd=QDate();  char sep('/');  //uint64_t firstSep,secondSep; portage 32 64  std::string::size_type firstSep,secondSep;  try {    if ( (firstSep=dateStr.find(sep)) != string::npos ) {      if ( (secondSep=dateStr.find(sep,firstSep+1)) != string::npos ) {        // suppose day/month/year        // from_uk_string only defined in recent versions of boost//         dateBegin=boost::gregorian::from_uk_string(dateStr);//         dateEnd=boost::gregorian::from_uk_string(dateStr);        // current version knows only year/month/day        string day(dateStr,0,firstSep);        string month(dateStr,firstSep+1,secondSep-firstSep);        string year(dateStr,secondSep+1);        string newDateStr=year+'/'+month+'/'+day;        dateBegin=QDate::fromString(newDateStr.c_str());        dateEnd=QDate::fromString(newDateStr.c_str());      }      else {         // one separator : suppose month/year        // find end of month        string month(dateStr,0,firstSep);        string year(dateStr,firstSep+1);        unsigned short monthNum=atoi(month.c_str());        unsigned short yearNum=atoi(year.c_str());        dateBegin=QDate(yearNum,monthNum,1);        dateEnd=dateBegin.addMonths(1).addDays(-1);      }    }    else if (! dateStr.empty()) {      // no separator : suppose year      unsigned short yearNum=atoi(dateStr.c_str());      dateBegin=QDate(yearNum,01,01);      dateEnd=QDate(yearNum,12,31);    }  }  //catch (boost::bad_lexical_cast& e) {   catch (std::exception& e) {     DRLOGINIT;    LWARN << "Warning: " << e.what();    LWARN << "Failed parsing of date [" << dateStr << "]";    // do nothing, keep not_a_date_time as default value  }}

QString PartialDate::range(const PartialDate& d) const{	if (year() != d.year())		return asShortString() + "-" + d.asShortString();	QString result = numberToString(year());	if (month() != d.month())		return QString("%1.%2-%3").arg(year()).arg(asShortString(Month | Day))				.arg(d.asShortString(Month | Day));	else if (day() != d.day())		return QString("%1.%2.%3-%4").arg(year()).arg(month())				.arg(asShortString(Day)).arg(d.asShortString(Day));	else return asShortString();}

Datetime Datetime::preMonth() const {    Datetime result;    if (*this == Null<Datetime>())        return result;    try {        int m = month();        result = (m == 1) ? Datetime(year()-1, 12, 1) : Datetime(year(), m-1, 1);    } catch(...) {        result = Datetime::min();    }    return result;}

Datetime Datetime::preHalfyear() const {    Datetime result;    if (*this == Null<Datetime>())        return result;    try {        int m = startOfHalfyear().month();        result = (m <= 6) ? Datetime(year()-1, 7, 1) : Datetime(year(), 1, 1);    } catch(...) {        result = Datetime::min();    }    return result;}

Datetime Datetime::preQuarter() const {    Datetime result;    if (*this == Null<Datetime>())        return result;    try {        int m = startOfQuarter().month();        result = (m == 1) ? Datetime(year()-1, 10, 1) : Datetime(year(), m-3, 1);    } catch(...) {        result = Datetime::min();    }    return result;}

  /* Negativa! */  Date & Julian::add_year(int y){    if(day()==29&&month()==2){ //b
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