Time::Piece Perl日期时间处理

摘要:

    use Time::Piece;
    
    my $t = localtime;
    print "Time is $t\n";
    print "Year is ", $t->year, "\n";

用法:

    $t->sec                 # also available as $t->second
    $t->min                 # also available as $t->minute
    $t->hour                # 24 hour
    $t->mday                # also available as $t->day_of_month
    $t->mon                 # 1 = January
    $t->_mon                # 0 = January
    $t->monname             # Feb
    $t->month               # same as $t->monname
    $t->fullmonth           # February
    $t->year                # based at 0 (year 0 AD is, of course 1 BC)
    $t->_year               # year minus 1900
    $t->yy                  # 2 digit year
    $t->wday                # 1 = Sunday
    $t->_wday               # 0 = Sunday
    $t->day_of_week         # 0 = Sunday
    $t->wdayname            # Tue
    $t->day                 # same as wdayname
    $t->fullday             # Tuesday
    $t->yday                # also available as $t->day_of_year, 0 = Jan 01
    $t->isdst               # also available as $t->daylight_savings

    $t->hms                 # 12:34:56
    $t->hms(".")            # 12.34.56
    $t->time                # same as $t->hms

    $t->ymd                 # 2000-02-29
    $t->date                # same as $t->ymd
    $t->mdy                 # 02-29-2000
    $t->mdy("/")            # 02/29/2000
    $t->dmy                 # 29-02-2000
    $t->dmy(".")            # 29.02.2000
    $t->datetime            # 2000-02-29T12:34:56 (ISO 8601)
    $t->cdate               # Tue Feb 29 12:34:56 2000
    "$t"                    # same as $t->cdate

    $t->epoch               # seconds since the epoch
    $t->tzoffset            # timezone offset in a Time::Seconds object

    $t->julian_day          # number of days since Julian period began
    $t->mjd                 # modified Julian date (JD-2400000.5 days)

    $t->week                # week number (ISO 8601)

    $t->is_leap_year        # true if it its
    $t->month_last_day      # 28-31

    $t->time_separator($s)  # set the default separator (default ":")
    $t->date_separator($s)  # set the default separator (default "-")
    $t->day_list(@days)     # set the default weekdays
    $t->mon_list(@days)     # set the default months

    $t->strftime(FORMAT)    # same as POSIX::strftime (without the overhead
                            # of the full POSIX extension)
    $t->strftime()          # "Tue, 29 Feb 2000 12:34:56 GMT"
    
    Time::Piece->strptime(STRING, FORMAT)
                            # see strptime man page. Creates a new
                            # Time::Piece object

日期计算:

简单日期加减

    use Time::Seconds;
    
    my $seconds = $t1 - $t2;
    $t1 += ONE_DAY; # add 1 day (constant from Time::Seconds)

下列的算是是有效的($t1 and $t2 是Time::Piece objects)

    $t1 - $t2; # returns Time::Seconds object
    $t1 - 42; # returns Time::Piece object
    $t1 + 533; # returns Time::Piece object

然而 Time::Piece 相加会产生异常，相减返回Time::Seconds object，通过Time::Seconds API返回分钟，小时，天，星期，年。

除了能加秒, 还有两个API函数能加月，年:

$t->add_months(6);
$t->add_years(5);

月和年通过负数可以变为减。

日期比较操作

日期可以使用 "<", ">", "<=", ">=", "<=>", "==" and "!=" 进行比较

日期解析

Time::Piece 通过  strptime()  函数(from FreeBSD), 进行日期格式的转换.

  my $t = Time::Piece->strptime("Sunday 3rd Nov, 1943",
                                "%A %drd %b, %Y");
  
  print $t->strftime("%a, %d %b %Y");

附录一：Time::Seconds

常量:

    ONE_DAY
    ONE_WEEK
    ONE_HOUR
    ONE_MINUTE
    ONE_MONTH
    ONE_YEAR
    ONE_FINANCIAL_MONTH
    LEAP_YEAR
    NON_LEAP_YEAR

方法:

    my $val = Time::Seconds->new(SECONDS)
    $val->seconds;
    $val->minutes;
    $val->hours;
    $val->days;
    $val->weeks;
    $val->months;
    $val->financial_months; # 30 days
    $val->years;
    $val->pretty; # gives English representation of the delta

附录二：转义符说明：

     %A    is replaced by national representation of the full weekday name.

     %a    is replaced by national representation of the abbreviated weekday
       name.

     %B    is replaced by national representation of the full month name.

     %b    is replaced by national representation of the abbreviated month
       name.

     %C    is replaced by (year / 100) as decimal number; single digits are
       preceded by a zero.

     %c    is replaced by national representation of time and date.

     %D    is equivalent to ``%m/%d/%y''.

     %d    is replaced by the day of the month as a decimal number (01-31).

     %E* %O*
       POSIX locale extensions.  The sequences %Ec %EC %Ex %EX %Ey %EY %Od
       %Oe %OH %OI %Om %OM %OS %Ou %OU %OV %Ow %OW %Oy are supposed to
       provide alternate representations.

       Additionally %OB implemented to represent alternative months names
       (used standalone, without day mentioned).

     %e    is replaced by the day of the month as a decimal number (1-31);
       single digits are preceded by a blank.

     %F    is equivalent to ``%Y-%m-%d''.

     %G    is replaced by a year as a decimal number with century.  This year
       is the one that contains the greater part of the week (Monday as
       the first day of the week).

     %g    is replaced by the same year as in ``%G'', but as a decimal number
       without century (00-99).

     %H    is replaced by the hour (24-hour clock) as a decimal number
       (00-23).

     %h    the same as %b.

     %I    is replaced by the hour (12-hour clock) as a decimal number
       (01-12).

     %j    is replaced by the day of the year as a decimal number (001-366).

     %k    is replaced by the hour (24-hour clock) as a decimal number (0-23);
       single digits are preceded by a blank.

     %l    is replaced by the hour (12-hour clock) as a decimal number (1-12);
       single digits are preceded by a blank.

     %M    is replaced by the minute as a decimal number (00-59).

     %m    is replaced by the month as a decimal number (01-12).

     %n    is replaced by a newline.

     %O*   the same as %E*.

     %p    is replaced by national representation of either "ante meridiem"
       (a.m.)  or "post meridiem" (p.m.)  as appropriate.

     %R    is equivalent to ``%H:%M''.

     %r    is equivalent to ``%I:%M:%S %p''.

     %S    is replaced by the second as a decimal number (00-60).

     %s    is replaced by the number of seconds since the Epoch, UTC (see
       mktime(3)).

     %T    is equivalent to ``%H:%M:%S''.

     %t    is replaced by a tab.

     %U    is replaced by the week number of the year (Sunday as the first day
       of the week) as a decimal number (00-53).

     %u    is replaced by the weekday (Monday as the first day of the week) as
       a decimal number (1-7).

     %V    is replaced by the week number of the year (Monday as the first day
       of the week) as a decimal number (01-53).  If the week containing
       January 1 has four or more days in the new year, then it is week 1;
       otherwise it is the last week of the previous year, and the next
       week is week 1.

     %v    is equivalent to ``%e-%b-%Y''.

     %W    is replaced by the week number of the year (Monday as the first day
       of the week) as a decimal number (00-53).

     %w    is replaced by the weekday (Sunday as the first day of the week) as
       a decimal number (0-6).

     %X    is replaced by national representation of the time.

     %x    is replaced by national representation of the date.

     %Y    is replaced by the year with century as a decimal number.

     %y    is replaced by the year without century as a decimal number
       (00-99).

     %Z    is replaced by the time zone name.

     %z    is replaced by the time zone offset from UTC; a leading plus sign
       stands for east of UTC, a minus sign for west of UTC, hours and
       minutes follow with two digits each and no delimiter between them
       (common form for RFC 822 date headers).

     %+    is replaced by national representation of the date and time (the
       format is similar to that produced by date(1)).

     %-*   GNU libc extension.    Do not do any padding when performing numeri-
       cal outputs.

     %_*   GNU libc extension.    Explicitly specify space for padding.

     %0*   GNU libc extension.    Explicitly specify zero for padding.

     %%    is replaced by '%'.