This is Info file pm.info, produced by Makeinfo version 1.68 from the input file bigpm.texi.  File: pm.info, Node: Data/Walker, Next: Data/Xtab, Prev: Data/Table, Up: Module List A tool for navigating through Perl data structures ************************************************** NAME ==== *Data::Walker* - A tool for navigating through Perl data structures SYNOPSIS ======== Without any explicit objects: use Data::Walker; Data::Walker->cli( $data_structure ); Object-style invocation: use Data::Walker; my $w = new Data::Walker; $w->walk( $data_structure ); $w->ls("-al"); $w->pwd; $w->cli; Importing methods into the current package: use Data::Walker qw(:direct); walk $data_structure; ls "-al"; pwd; cli; DESCRIPTION =========== This module allows you to "walk" an arbitrary Perl data structure in the same way that you can walk a directory tree from a UNIX command line. It reuses familiar unix commands (such as "ls", "cd", "pwd") and applies these to data structures. It has a command-line interface which behaves like a UNIX shell. You can also use object-style sytax to invoke the CLI commands from outside the CLI. Data::Walker objects are encapsulated, so that you can hop into and out of a CLI without losing state, and you can have several Data::Walker objects pointing at different structures. The main functions can also be imported and used directly from within the Perl debugger's CLI. INSTALLATION ============ To install this package, just into the directory which you created by untarring the package, and type the following: perl Makefile.PL make test make make install This will copy Walker.pm to your perl library directory for use by all perl scripts. You probably must be root to do this, unless you have installed a personal copy of perl or you have write access to a Perl lib directory. USAGE ===== You open a command-line interface by invoking the cli() function. use Data::Walker; Data::Walker->cli( $data_structure ); You can customize certain features, like so: use Data::Walker; $Data::Walker::Config{'skipdoublerefs'} = 0; Data::Walker->cli( $data_structure ); If you prefer to use object-style notation, then you can use this syntax to customize the settings. You can invoke the walk() method directly, our you can let the cli() method call walk() implicitly: use Data::Walker; my $w1 = new Data::Walker; $w1->walk( $data_structure ); $w1->cli; my $w2 = new Data::Walker; $w2->cli( $data_structure ); my $w3 = new Data::Walker( 'skipdoublerefs' => 0 ); $w3->walk( $data_structure ); $w3->cli(); $w3->showrecursion(0); $w3->cli(); You can also import most of the functions directly into the current package. This is especially useful from within the debugger (see the example below). use Data::Walker qw(:direct); walk $data_structure; ls "-al"; pwd; cli; When you use the :direct pragma and invoke the walk() function, a Data::Walker object is implicitly created, and is available as $Data::Walker::WALKER. Imagine a data structure like so: my $s = { a => [ 10, 20, "thirty" ], b => { "w" => "forty", "x" => "fifty", "y" => 60, "z" => \70, }, c => sub { print "I'm a data structure!\n"; }, d => 80, }; $s->{e} = \$s->{d}; Here is a sample CLI session examining this structure ('/>' is the prompt): /> /> ls -l a ARRAY (3) b HASH (4) c CODE d scalar 80 e SCALAR 80 /> cd a /->{a}> ls -al .. HASH (5) . ARRAY (3) 0 scalar 10 1 scalar 20 2 scalar 'thirty' /->{a}> cd ../b /->{b}> ls -al .. HASH (5) . HASH (4) w scalar 'forty' x scalar 'fifty' y scalar 60 z SCALAR 70 /->{b}> cd .. /> dump b dump--> 'b' $b = { 'x' => 'fifty', 'y' => 60, 'z' => \70, 'w' => 'forty' }; /> ls -al .. HASH (5) . HASH (5) a ARRAY (3) b HASH (4) c CODE d scalar 80 e SCALAR 80 /> ! $cur->{d} += 3 eval--> $cur->{d} += 3 retv--> 83 /> ls -al .. HASH (5) . HASH (5) a ARRAY (3) b HASH (4) c CODE d scalar 83 e SCALAR 83 /> Below is a sample debugger session examining this structure. Note that the walk() function returns a reference to the "cursor", which is itself a reference to whatever is the "current directory," so to speak. The actual Data::Walker object iself is managed implicitly, and is available as $Data::Walker::WALKER. When you are finished, you can undef this object directly, or use the unwalk() function, which does this for you. But if you saved a copy of the cursor, then you will need to undef this on your own. (violet) ~/perl/walker/Data-Walker-0.18 > perl -d sample_db Loading DB routines from perl5db.pl version 1.0401 Emacs support available. Enter h or `h h' for help. main::(sample:19): d => 80, DB<1> n main::(sample:22): $s->{e} = \$s->{d}; DB<1> n main::(sample:30): 1; DB<1> use Data::Walker qw(:direct) DB<2> $cur = walk $s DB<3> pwd / DB<4> ls a b c d e DB<5> lal .. HASH (5) . HASH (5) a ARRAY (3) b HASH (4) c CODE d scalar 80 e SCALAR 80 DB<6> cd a /->{a} DB<7> ll 0 scalar 10 1 scalar 20 2 scalar 'thirty' DB<8> cd '../b' /->{b} DB<9> lal .. HASH (5) . HASH (4) w scalar 'forty' x scalar 'fifty' y scalar 60 z SCALAR 70 DB<10> cd '..' / DB<11> dump b dump--> 'b' $b = { 'x' => 'fifty', 'y' => 60, 'z' => \70, 'w' => 'forty' }; DB<12> ll a ARRAY (3) b HASH (4) c CODE d scalar 80 e SCALAR 80 DB<13> $$cur->{d} += 3 DB<14> ll a ARRAY (3) b HASH (4) c CODE d scalar 83 e SCALAR 83 DB<15> DB<16> pwd / DB<17> cli /> cd b /->{b}> ls -l w scalar 'forty' x scalar 'fifty' y scalar 60 z SCALAR 70 /->{b}> print y 60 /->{b}> print x fifty /->{b}> exit DB<18> pwd /->{b} DB<19> ll w scalar 'forty' x scalar 'fifty' y scalar 60 z SCALAR 70 DB<20> unwalk DB<21> undef $cur DB<22> The following commands are available from within the CLI. With these commands, you can navigate around the data structure as if it were a directory tree. cd like UNIX cd ls like UNIX ls (also respects options -a, -l) print prints the item as a scalar dump invokes Data::Dumper set set configuration variables show show configuration variables ! or eval eval arbitrary perl (careful!) help this help message help set lists the available config variables For each session (or object) the following items can be configured: rootname (default: '/' ) displays the root node refname (default: 'ref' ) displays embedded refs scalarname (default: 'scalar') displays simple scalars undefname (default: 'undef' ) displays undefined scalars maxdepth (default: 1 ) maximum dump-depth (Data::Dumper) indent (default: 1 ) amount of indent (Data::Dumper) lscol1width (default: 15 ) column widths for 'ls' displays lscol2width (default: 25 ) column widths for 'ls' displays showrecursion (default: 1 ) note recursion in the prompt showids (default: 0 ) show ref id numbers in ls lists skipdoublerefs (default: 1 ) hop over ref-to-refs during walks skipwarning (default: 1 ) warn when hopping over ref-to-refs truncatescalars (default: 37 ) truncate scalars in 'ls' displays autoprint (default: 1 ) print directory after chdir when not in CLI promptchar (default: '>') customize the session prompt arrowshaft (default: '-') ('-' in '->') arrowhead (default: '>') ('>' in '->') curname (default: 'cur' ) how to refer to the cursor for evals parname (default: 'par' ) how to refer to the parent ref for evals CHANGES ======= * Version 1.02-1.04 Minor changes to installer tests. * Version 1.01 Minor changes to the documentation. Added walker_http.pl, which is a library for using Data::Walker together with HTTP::Daemon to view objects with a Web browser. Two example scripts are also included. * Version 0.21 Minor changes to the documentation * Version 0.19-0.20 Added new tests and updated the documentation. * Version 0.18 Completely separated the CLI loop, command-parsing regexes, and the functions which implement the commands. AUTOLOAD is now set up to handle any commands that the CLI can parse (except for eval() ). By using the :direct pragma, you can now import AUTOLOADed functions into the current package, so that you can easily invoke them from the perl debugger. * Version 0.16-0.17 The Data::Walker objects are now fully encapsulated. NOTE: The walk() function has been separated into two functions, namely walk() and cli(). The usage instructions have changed. Please have a look. * Version 0.15 Reorganized the installation tests. A few minor changes to the module itself. * Version 0.13-0.14 Moved some functionality from the CLI-loop into distinct functions. * Version 0.12 Blessed references to non-hashes are now handled correctly. Modified the output of "ls" commands (looks different). Added new options: showids, lscol2width, scalarname, undefname, skipwarning Numerous internal changes. * Version 0.11 Fixed some misspellings in the help information. Modified the pretty-print format of scalars. Added some new comments to the source code. Various other small updates. THANKS ====== Thanks to Gurusamy Sarathy for writing Data::Dumper, and to Dominique Dumont for writing Tk::ObjScanner. Thanks to Matthew Persico for sending some ideas on how this module might be useful in the debugger. Thanks to Scott Lindsey for pointing out that this module is useful for reading files created with the Storable module, and for sending a sample script to do this. AUTHOR ====== John Nolan jpnolan@sonic.net 1999,2000. A copyright statment is contained within the source code itself.  File: pm.info, Node: Data/Xtab, Next: Date/Business, Prev: Data/Walker, Up: Module List Pivot (cross-tabulate) a table of data. *************************************** NAME ==== Data::Xtab - Pivot (cross-tabulate) a table of data. DESCRIPTION =========== This module allows you to feed it tables of data to be pivoted in such a way that they can be easily used in a report or graph. Here is an example of input data: 'A', 'JUN', 7 'A', 'JAN', 4 'B', 'JAN', 3 'B', 'FEB', 39 'C', 'MAY', 8 'A', 'JUN', 100 The output would be rendered as: JAN FEB MAR APR MAY JUN A 4 0 0 0 0 107 B 3 39 0 0 0 0 C 0 0 0 0 8 0 The first column in the table ends up becoming the data series. The second column becomes the headers, under which the third column is summed. If more than one data records for the same data series and header column appear in the input data, the values are totalled for that intersection. This module was designed to be used in conjunction with the GIFGraph module, but no doubt has other uses. SYNOPSIS ======== #!/usr/local/bin/perl use Data::Xtab; use GIFgraph::lines; use CGI; $query = new CGI; print $query->header("image/gif"); my @data = ( ['A', 'FEB', 31], ['A', 'FEB', 12], ['A', 'MAR', 18], ['A', 'MAR', 29], ['A', 'APR', 142], ['B', 'FEB', 217], ['B', 'FEB', 14], ['B', 'MAR', 121], ['B', 'APR', 37], ['C', 'MAR', 39], ['C', 'MAR', 8], ['C', 'APR', 100] ); # The outputcols parameter is used to enumerate the # columns that should be used in the output table, and # more importantly, the order in which they should appear. # my @outputcols = ('JAN', 'FEB', 'MAR', 'APR'); my $xtab = new Data::Xtab(\@data, \@outputcols); my @graph_data = $xtab->graph_data; $my_graph = new GIFgraph::lines(); $my_graph->set( 'x_label' => 'Month', 'y_label' => 'Sales', 'title' => 'Monthly Sales', 'y_max_value' => 450, 'y_tick_number' => 5, 'y_label_skip' => 2 ); print $my_graph->plot( \@graph_data ); AUTHOR ====== Copyright (c) 1997, Brian Jepson You may distribute this kit under the same terms as Perl itself.  File: pm.info, Node: Date/Business, Next: Date/Calc, Prev: Data/Xtab, Up: Module List fast calendar and business date calculations ******************************************** NAME ==== Date::Business - fast calendar and business date calculations SYNOPSIS ======== All arguments to the Date::Business constructor are optional. # simplest case, default is today's date (localtime) $d = new Date::Business(); # initialize with date string, # offset in business days is optional $d = new Date::Business(DATE => '19991124' [, OFFSET => ]); # initialize with another Date::Business object # offset in business days is optional $x = new Date::Business(DATE => $d [, OFFSET => ]); # initialize with holiday function (see Holidays, below) $d = new Date::Business(HOLIDAY => \&holiday); # force weekends/holidays to the previous or next business day $d = new Date::Business(FORCE => 'prev'); # Friday (usually) $d = new Date::Business(FORCE => 'next'); # Monday (usually) $d->image(); # returns YYYYMMDD string $d->value(); # returns Unix time as integer $d->day_of_week(); # 0 = Sunday $d->datecmp($x); # are two dates equal? $d->eq($x); # synonym for datecmp $d->lt($x); # less than $d->gt($x); # greater than Calendar date functions $d->next(); # next calendar day $d->prev(); # previous calendar day $d->add(); # adds n calendar days $d->sub(); # subtracts n calendar days $d->diff($x); # difference between two dates Business date functions $d->nextb(); # next business day $d->prevb(); # previous business day $d->addb(); # adds n business days $d->subb(); # subtracts n business days $d->diffb($x); # difference between two business dates $d->diffb($x, 'next'); # treats $d weekend/holiday as next business date $d->diffb($x, 'next', 'next'); # treats $x weekend/holiday as above DESCRIPTION =========== Date::Business provides the functionality to perform simple date manipulations quickly. Support for calendar date and business date math is provided. Business dates are weekdays only. Adding 1 to a weekend returns Monday, subtracting 1 returns Friday. The difference in business days between Friday and the following Monday (using the diffb function) is one business day. The number of business days between Friday and the following Monday (using the betweenb function) is zero. EXAMPLE ======= Date::Business works very well for iterating over dates, and determining start and end dates of arbitray n business day periods (e.g. consider how to perform a computation for a series of business days starting from an arbitrary day). $end = new Date::Business(); # today # 10 business days ago $start = new Date::Business(DATE => $end, OFFSET => -10); while (!$start->gt($end)) { compute_something($start); $start->nextb(); } HOLIDAYS ======== Optionally, a reference to a function that counts the number of holidays in a given date range can be passed. Business date addition, subtraction, and difference functions will consider holidays. Sample holiday function: # MUST BE NON-WEEKEND HOLIDAYS !!! sub holiday($$) { my($start, $end) = @_; my($numHolidays) = 0; my($holiday, @holidays); push @holidays, '19981225'; # Christmas push @holidays, '19990101'; $ New Year's foreach $holiday (@holidays) { $numHolidays++ if ($start le $holiday && $end ge $holiday); } return $numHolidays; } Example using the holiday function: # 10 business days after 21 DEC 1998, where # 25 DEC 1998 and 01 JAN 1999 are holidays # $d = new Date::Business(DATE => '19981221', OFFSET => 10, HOLIDAY => \&holiday); print $d->image."\n"; # prints 19990106 The diffb() function explained ============================== The difference between two business days is relatively straightforward when the operands are business days. The difference (in business days) between two days when one or both of those days is a weekend or holiday is ambiguous. The 'next' and 'prev' parameters are used to resolve the ambiguity. The first parameter to the diffb function is the other date. The second parameter indicates that 'self' is to be treated as the previous or next business date if it is not a business date. The third parameter is similar to the second parameter but applies to the 'other' date. The default behavior is treat both dates as if the 'prev' option was set. For example: $d = new Date::Business(DATE => '19991225'); # saturday $x = new Date::Business(DATE => '19991225'); # saturday print $d->image; # prints 19991225 print $d->diffb($x); # prints 0 print $d->diffb($x, 'prev', 'next'); # prints -1 print $d->diffb($x, 'next', 'prev'); # prints 1 print $d->diffb($x, 'next', 'next'); # prints 0 CAVEATS ======= Business dates may be initialized with values in the range of '19700101' through '20380119'. The range of valid results are '19011213' through '20380119'. Computations on dates that exceed the maximum value will wrap around. (i.e. the day after '20380119' is '19011214'). Computations that exceed the minimum value will result in the minimum value. (i.e. the day before '19011213' is '19011213')  File: pm.info, Node: Date/Calc, Next: Date/Christmas, Prev: Date/Business, Up: Module List Gregorian calendar date calculations ************************************ NAME ==== Date::Calc - Gregorian calendar date calculations PREFACE ======= This package consists of a C library and a Perl module (which uses the C library, internally) for all kinds of date calculations based on the Gregorian calendar (the one used in all western countries today), thereby complying with all relevant norms and standards: ISO/R 2015-1971, DIN 1355 and, to some extent, ISO 8601 (where applicable). (See also http://www.engelschall.com/u/sb/download/Date-Calc/DIN1355/ for a scan of part of the "DIN 1355" document (in German)). The module of course handles year numbers of 2000 and above correctly ("Year 2000" or "Y2K" compliance) - actually all year numbers from 1 to the largest positive integer representable on your system (which is at least 32767) can be dealt with. Note that this package projects the Gregorian calendar back until the year 1 A.D. - even though the Gregorian calendar was only adopted in 1582 by most (not all) European countries, in obedience to the corresponding decree of catholic pope Gregor I in that year. Some (mainly protestant) countries continued to use the Julian calendar (used until then) until as late as the beginning of the 20th century. Finally, note that this package is not intended to do everything you could ever imagine automagically for you; it is rather intended to serve as a toolbox (in the best of UNIX spirit and traditions) which should, however, always get you where you want to go. See the section "RECIPES" at the bottom of this document for solutions to common problems! If nevertheless you can't figure out how to solve a particular problem, please let me know! (See e-mail address at the end of this document.) SYNOPSIS ======== use Date::Calc qw( Days_in_Year Days_in_Month Weeks_in_Year leap_year check_date check_business_date Day_of_Year Date_to_Days Day_of_Week Week_Number Week_of_Year Monday_of_Week Nth_Weekday_of_Month_Year Standard_to_Business Business_to_Standard Delta_Days Delta_DHMS Add_Delta_Days Add_Delta_DHMS Add_Delta_YMD System_Clock Today Now Today_and_Now Easter_Sunday Decode_Month Decode_Day_of_Week Decode_Language Decode_Date_EU Decode_Date_US Compress Uncompress check_compressed Compressed_to_Text Date_to_Text Date_to_Text_Long English_Ordinal Calendar Month_to_Text Day_of_Week_to_Text Day_of_Week_Abbreviation Language_to_Text Language Languages Decode_Date_EU2 Decode_Date_US2 Parse_Date ); use Date::Calc qw(:all); Days_in_Year $days = Days_in_Year($year,$month); Days_in_Month $days = Days_in_Month($year,$month); Weeks_in_Year $weeks = Weeks_in_Year($year); leap_year if (leap_year($year)) check_date if (check_date($year,$month,$day)) check_business_date if (check_business_date($year,$week,$dow)) Day_of_Year $doy = Day_of_Year($year,$month,$day); Date_to_Days $days = Date_to_Days($year,$month,$day); Day_of_Week $dow = Day_of_Week($year,$month,$day); Week_Number $week = Week_Number($year,$month,$day); Week_of_Year ($week,$year) = Week_of_Year($year,$month,$day); Monday_of_Week ($year,$month,$day) = Monday_of_Week($week,$year); Nth_Weekday_of_Month_Year if (($year,$month,$day) = Nth_Weekday_of_Month_Year($year,$month,$dow,$n)) Standard_to_Business ($year,$week,$dow) = Standard_to_Business($year,$month,$day); Business_to_Standard ($year,$month,$day) = Business_to_Standard($year,$week,$dow); Delta_Days $Dd = Delta_Days($year1,$month1,$day1, $year2,$month2,$day2); Delta_DHMS ($Dd,$Dh,$Dm,$Ds) = Delta_DHMS($year1,$month1,$day1, $hour1,$min1,$sec1, $year2,$month2,$day2, $hour2,$min2,$sec2); Add_Delta_Days ($year,$month,$day) = Add_Delta_Days($year,$month,$day, $Dd); Add_Delta_DHMS ($year,$month,$day, $hour,$min,$sec) = Add_Delta_DHMS($year,$month,$day, $hour,$min,$sec, $Dd,$Dh,$Dm,$Ds); Add_Delta_YMD ($year,$month,$day) = Add_Delta_YMD($year,$month,$day, $Dy,$Dm,$Dd); System_Clock ($year,$month,$day, $hour,$min,$sec, $doy,$dow,$dst) = System_Clock(); Today ($year,$month,$day) = Today(); Now ($hour,$min,$sec) = Now(); Today_and_Now ($year,$month,$day, $hour,$min,$sec) = Today_and_Now(); Easter_Sunday ($year,$month,$day) = Easter_Sunday($year); Decode_Month if ($month = Decode_Month($string)) Decode_Day_of_Week if ($dow = Decode_Day_of_Week($string)) Decode_Language if ($lang = Decode_Language($string)) Decode_Date_EU if (($year,$month,$day) = Decode_Date_EU($string)) Decode_Date_US if (($year,$month,$day) = Decode_Date_US($string)) Compress $date = Compress($year,$month,$day); Uncompress if (($century,$year,$month,$day) = Uncompress($date)) check_compressed if (check_compressed($date)) Compressed_to_Text $string = Compressed_to_Text($date); Date_to_Text $string = Date_to_Text($year,$month,$day); Date_to_Text_Long $string = Date_to_Text_Long($year,$month,$day); English_Ordinal $string = English_Ordinal($number); Calendar $string = Calendar($year,$month); Month_to_Text $string = Month_to_Text($month); Day_of_Week_to_Text $string = Day_of_Week_to_Text($dow); Day_of_Week_Abbreviation $string = Day_of_Week_Abbreviation($dow); Language_to_Text $string = Language_to_Text($lang); Language $lang = Language(); Language($lang); $oldlang = Language($newlang); Languages $max_lang = Languages(); Decode_Date_EU2 if (($year,$month,$day) = Decode_Date_EU2($string)) Decode_Date_US2 if (($year,$month,$day) = Decode_Date_US2($string)) Parse_Date if (($year,$month,$day) = Parse_Date($string)) Version $string = Date::Calc::Version(); IMPORTANT NOTES =============== (See the section "RECIPES" at the bottom of this document for solutions to common problems!) * "Year 2000" ("Y2K") compliance The upper limit for any year number in this module is only given by the size of the largest positive integer that can be represented in a variable of the C type "int" on your system, which is at least 32767, according to the ANSI C standard (exceptions see below). In order to simplify calculations, this module projects the gregorian calendar back until the year 1 A.D. - i.e., back *BEYOND* the year 1582 when this calendar was first decreed by the catholic pope Gregor I! Therefore, *BE SURE TO ALWAYS SPECIFY "1998" WHEN YOU MEAN "1998"*, for instance, and *DO NOT WRITE "98" INSTEAD*, because this will in fact perform a calculation based on the year "98" A.D. and *NOT* "1998"! The only exceptions from this rule are the functions which contain the word "compress" in their names (which only handle years between 1970 and 2069 and also accept the abbreviations "00" to "99"), and the functions whose names begin with "Decode_Date_" (which map year numbers below 100 to the range 1970 - 2069, using a technique known as "windowing"). * First index ALL ranges in this module start with "1", *NOT* "0"! I.e., the day of month, day of week, day of year, month of year, week of year, first valid year number and language ALL start counting at one, *NOT* zero! The only exception is the function "`Week_Number()'", which may in fact return "0" when the given date actually lies in the last week of the PREVIOUS year. * Function naming conventions Function names completely in lower case indicate a boolean return value. * Boolean values Boolean values in this module are always a numeric zero ("0") for "false" and a numeric one ("1") for "true". * Exception handling The functions in this module will usually die with a corresponding error message if their input parameters, intermediate results or output values are out of range. The following functions handle errors differently: - check_date() - check_business_date() - check_compressed() (which return a "false" return value when the given input does not represent a valid date), - Nth_Weekday_of_Month_Year() (which returns an empty list if the requested 5th day of week does not exist), - Decode_Month() - Decode_Day_of_Week() - Decode_Language() - Compress() (which return "0" upon failure or invalid input), and - Decode_Date_EU() - Decode_Date_US() - Decode_Date_EU2() - Decode_Date_US2() - Parse_Date() - Uncompress() (which return an empty list upon failure or invalid input). Note that you can always catch an exception thrown by any of the functions in this module and handle it yourself by enclosing the function call in an "eval" with curly brackets and checking the special variable "`$@'" (see `perlfunc(1)' in this node for details). DESCRIPTION =========== * `use Date::Calc qw( Days_in_Year Days_in_Month ... );' * `use Date::Calc qw(:all);' You can either specify the functions you want to import explicitly by enumerating them between the parentheses of the "`qw()'" operator, or you can use the ":all" tag instead to import ALL available functions. * `$days = Days_in_Year($year,$month);' This function returns the sum of the number of days in the months starting with January up to and including "$month" in the given year "$year". I.e., "`Days_in_Year(1998,1)'" returns "31", "`Days_in_Year(1998,2)'" returns "59", "`Days_in_Year(1998,3)'" returns "90", and so on. Note that "`Days_in_Year($year,12)'" returns the number of days in the given year "$year", i.e., either "`365'" or "`366'". * `$days = Days_in_Month($year,$month);' This function returns the number of days in the given month "$month" of the given year "$year". The year must always be supplied, even though it is only needed when the month is February, in order to determine wether it is a leap year or not. I.e., "`Days_in_Month(1998,1)'" returns "31", "`Days_in_Month(1998,2)'" returns "28", "`Days_in_Month(2000,2)'" returns "29", "`Days_in_Month(1998,3)'" returns "31", and so on. * `$weeks = Weeks_in_Year($year);' This function returns the number of weeks in the given year "$year", i.e., either "52" or "53". * `if (leap_year($year))' This function returns "true" ("1") if the given year "$year" is a leap year and "false" ("0") otherwise. * `if (check_date($year,$month,$day))' This function returns "true" ("1") if the given three numerical values "$year", "$month" and "$day" constitute a valid date, and "false" ("0") otherwise. * `if (check_business_date($year,$week,$dow))' This function returns "true" ("1") if the given three numerical values "$year", "`$week'" and "`$dow'" constitute a valid date in business format, and "false" ("0") otherwise. *Beware* that this function does *NOT* compute wether a given date is a business day (i.e., Monday to Friday)! To do so, use "`(Day_of_Week($year,$month,$day) < 6)'" instead. * `$doy = Day_of_Year($year,$month,$day);' This function returns the (relative) number of the day of the given date in the given year. E.g., "`Day_of_Year($year,1,1)'" returns "1", "`Day_of_Year($year,2,1)'" returns "32", and "`Day_of_Year($year,12,31)'" returns either "`365'" or "`366'". * `$days = Date_to_Days($year,$month,$day);' This function returns the (absolute) number of the day of the given date, where counting starts at the 1st of January of the year 1 A.D. I.e., "`Date_to_Days(1,1,1)'" returns "1", "`Date_to_Days(1,12,31)'" returns "`365'", "`Date_to_Days(2,1,1)'" returns "`366'", "`Date_to_Days(1998,5,1)'" returns "`729510'", and so on. * `$dow = Day_of_Week($year,$month,$day);' This function returns the number of the day of week of the given date. The function returns "1" for Monday, "2" for Tuesday and so on until "7" for Sunday. Note that in the Hebrew calendar (on which the Christian calendar is based), the week starts with Sunday and ends with the Sabbath or Saturday (where according to the Genesis (as described in the Bible) the Lord rested from creating the world). In medieval times, catholic popes have decreed the Sunday to be the official day of rest, in order to dissociate the Christian from the Hebrew belief. Nowadays, the Sunday AND the Saturday are commonly considered (and used as) days of rest, usually referred to as the "week-end". Consistent with this practice, current norms and standards (such as ISO/R 2015-1971, DIN 1355 and ISO 8601) define the Monday as the first day of the week. * `$week = Week_Number($year,$month,$day);' This function returns the number of the week the given date lies in. If the given date lies in the *LAST* week of the PREVIOUS year, "0" is returned. If the given date lies in the FIRST week of the NEXT year, "`Weeks_in_Year($year) + 1'" is returned. * `($week,$year) = Week_of_Year($year,$month,$day);' This function returns the number of the week the given date lies in, as well as the year that week belongs to. I.e., if the given date lies in the *LAST* week of the PREVIOUS year, "`(Weeks_in_Year($year-1), $year-1)'" is returned. If the given date lies in the FIRST week of the NEXT year, "`(1, $year+1)'" is returned. Otherwise, "`(Week_Number($year,$month,$day), $year)'" is returned. * `($year,$month,$day) = Monday_of_Week($week,$year);' This function returns the date of the first day of the given week, i.e., the Monday. "$year" must be greater than or equal to "1", and "`$week'" must lie in the range "1" to "`Weeks_in_Year($year)'". Note that you can write "`($year,$month,$day) = Monday_of_Week(Week_of_Year($year,$month,$day));'" in order to calculate the date of the Monday of the same week as the given date. * `if (($year,$month,$day) = Nth_Weekday_of_Month_Year($year,$month,$dow,$n))' This function calculates the date of the "$n"th day of week "`$dow'" in the given month "$month" and year "$year"; such as, for example, the 3rd Thursday of a given month and year. This can be used to send a notification mail to the members of a group which meets regularly on every 3rd Thursday of a month, for instance. (See the section "RECIPES" near the end of this document for a code snippet to actually do so.) "$year" must be greater than or equal to "1", "$month" must lie in the range "1" to "12", "`$dow'" must lie in the range "1" to "7" and "$n" must lie in the range "1" to "5", or a fatal error (with appropriate error message) occurs. The function returns an empty list when the 5th of a given day of week does not exist in the given month and year. * `($year,$week,$dow) = Standard_to_Business($year,$month,$day);' This function converts a given date from standard notation (year, month, day (of month)) to business notation (year, week, day of week). * `($year,$month,$day) = Business_to_Standard($year,$week,$dow);' This function converts a given date from business notation (year, week, day of week) to standard notation (year, month, day (of month)). * `$Dd = Delta_Days($year1,$month1,$day1, $year2,$month2,$day2);' This function returns the difference in days between the two given dates. The result is positive if the two dates are in chronological order, i.e., if date #1 comes chronologically *BEFORE* date #2, and negative if the order of the two dates is reversed. The result is zero if the two dates are identical. * `($Dd,$Dh,$Dm,$Ds) = Delta_DHMS($year1,$month1,$day1, $hour1,$min1,$sec1, $year2,$month2,$day2, $hour2,$min2,$sec2);' This function returns the difference in days, hours, minutes and seconds between the two given dates with times. All four return values will be positive if the two dates are in chronological order, i.e., if date #1 comes chronologically *BEFORE* date #2, and negative (in all four return values!) if the order of the two dates is reversed. This is so that the two functions "`Delta_DHMS()'" and "`Add_Delta_DHMS()'" (description see further below) are complementary, i.e., mutually inverse: Add_Delta_DHMS(@date1,@time1, Delta_DHMS(@date1,@time1, @date2,@time2)) yields "`(@date2,@time2)'" again, whereas Add_Delta_DHMS(@date2,@time2, map(-$_, Delta_DHMS(@date1,@time1, @date2,@time2))) yields "`(@date1,@time1)'", and Delta_DHMS(@date1,@time1, Add_Delta_DHMS(@date1,@time1, @delta)) yields "`@delta'" again. The result is zero (in all four return values) if the two dates and times are identical. * `($year,$month,$day) = Add_Delta_Days($year,$month,$day, $Dd);' This function has two principal uses: First, it can be used to calculate a new date, given an initial date and an offset (which may be positive or negative) in days, in order to answer questions like "today plus 90 days - which date gives that?". (In order to add a weeks offset, simply multiply the weeks offset with "7" and use that as your days offset.) Second, it can be used to convert the canonical representation of a date, i.e., the number of that day (where counting starts at the 1st of January in 1 A.D.), back into a date given as year, month and day. Because counting starts at "1", you will actually have to subtract "1" from the canonical date in order to get back the original date: $canonical = Date_to_Days($year,$month,$day); ($year,$month,$day) = Add_Delta_Days(1,1,1, $canonical - 1); Moreover, this function is the inverse of the function "`Delta_Days()'": Add_Delta_Days(@date1, Delta_Days(@date1, @date2)) yields "`@date2'" again, whereas Add_Delta_Days(@date2, -Delta_Days(@date1, @date2)) yields "`@date1'", and Delta_Days(@date1, Add_Delta_Days(@date1, $delta)) yields "`$delta'" again. * `($year,$month,$day, $hour,$min,$sec) = Add_Delta_DHMS($year,$month,$day, $hour,$min,$sec, $Dd,$Dh,$Dm,$Ds);' This function serves to add a days, hours, minutes and seconds offset to a given date and time, in order to answer questions like "today and now plus 7 days but minus 5 hours and then plus 30 minutes, what date and time gives that?": ($y,$m,$d,$H,$M,$S) = Add_Delta_DHMS(Today_and_Now(), +7,-5,+30,0); * `($year,$month,$day) = Add_Delta_YMD($year,$month,$day, $Dy,$Dm,$Dd);' This function serves to add a years, months and days offset to a given date. (In order to add a weeks offset, simply multiply the weeks offset with "7" and add this number to your days offset.) Note that the three offsets for years, months and days are applied separately from each other, in reverse order. (This also allows them to have opposite signs.) In other words, first the days offset is applied (using the function "`Add_Delta_Days()'", internally), then the months offset, and finally the years offset. If the resulting date happens to fall on a day beyond the end of the resulting month, like the 31st of April or the 29th of February (in non-leap years), then the day is replaced by the last valid day of that month in that year (e.g., the 30th of April or 28th of February). *BEWARE* that this behaviour differs from that of previous versions of this module! (Formerly, only the 29th of February in non-leap years was checked for (which - in contrast to the current version - was replaced by the 1st of March). Other possible invalid dates were not checked (and returned unwittingly), constituting a severe bug of previous versions.) *BEWARE* also that because of this replacement, but even more because a year and a month offset is not equivalent to a fixed number of days, the transformation performed by this function is *NOT REVERSIBLE*! This is in contrast to the functions "`Add_Delta_Days()'" and "`Add_Delta_DHMS()'", which for this very reason have inverse functions (namely "`Delta_Days()'" and "`Delta_DHMS()'"), whereas there exists no inverse for this function. Note that for this same reason, even @date = Add_Delta_YMD( Add_Delta_YMD(@date, $Dy,$Dm,$Dd), -$Dy,-$Dm,-$Dd); will (in general!) *NOT* return the initial date "`@date'"! (This might work in some cases, though.) Note that this is *NOT* a program bug but *NECESSARILY* so because of the varying lengths of years and months! * `($year,$month,$day, $hour,$min,$sec, $doy,$dow,$dst) = System_Clock();' If your operating system supports the corresponding system calls ("`time()'" and "`localtime()'"), this function will return the information provided by your system clock, i.e., the current date and time, the number of the day of year, the number of the day of week and a flag signaling wether daylight savings time is currently in effect or not. The ranges of values returned (and their meanings) are as follows: $year : should at least cover 1900..2038 $month : 1..12 $day : 1..31 $hour : 0..23 $min : 0..59 $sec : 0..59 (0..61 on some systems) $doy : 1..366 $dow : 1..7 $dst : -1..1 The day of week ("`$dow'") will be "1" for Monday, "2" for Tuesday and so on until "7" for Sunday. The daylight savings time flag ("$dst") will be "`-1'" if this information is not available on your system, "0" for no daylight savings time (i.e., normal time) and "1" when daylight savings time is in effect. If your operating system does not provide the necessary system calls, calling this function will result in a fatal "not available on this system" error message. If you want to handle this exception yourself, use "eval" as follows: eval { ($year,$month,$day, $hour,$min,$sec, $doy,$dow,$dst) = System_Clock(); }; if ($@) { # Handle missing system clock # (For instance, ask user to enter this information manually) } Note that curlies ("{" and "}") are used here to delimit the statement to be "eval"ed (which is the way to catch exceptions in Perl), and not quotes (which is a way to evaluate Perl expressions at runtime). * `($year,$month,$day) = Today();' This function returns a subset of the values returned by the function "`System_Clock()'" (see above for details), namely the current year, month and day. A fatal "not available on this system" error message will appear if the corresponding system calls are not supported by your current operating system. * `($hour,$min,$sec) = Now();' This function returns a subset of the values returned by the function "`System_Clock()'" (see above for details), namely the current time (hours, minutes and full seconds). A fatal "not available on this system" error message will appear if the corresponding system calls are not supported by your current operating system. * `($year,$month,$day, $hour,$min,$sec) = Today_and_Now();' This function returns a subset of the values returned by the function "`System_Clock()'" (see above for details), namely the current date (year, month, day) and time (hours, minutes and full seconds). A fatal "not available on this system" error message will appear if the corresponding system calls are not supported by your current operating system. * `($year,$month,$day) = Easter_Sunday($year);' This function calculates the date of easter sunday for all years in the range from 1583 to 2299 (all other year numbers will result in a fatal "year out of range" error message) using the method known as the "Gaussian Rule". Some related christian feast days which depend on the date of easter sunday: Carnival Monday / Rosenmontag / Veille du Mardi Gras = -48 days Mardi Gras / Karnevalsdienstag / Mardi Gras = -47 days Ash Wednesday / Aschermittwoch / Mercredi des Cendres = -46 days Palm Sunday / Palmsonntag / Dimanche des Rameaux = -7 days Easter Friday / Karfreitag / Vendredi Saint = -2 days Easter Saturday / Ostersamstag / Samedi de Paques = -1 day Easter Monday / Ostermontag / Lundi de Paques = +1 day Ascension of Christ / Christi Himmelfahrt / Ascension = +39 days Whitsunday / Pfingstsonntag / Dimanche de Pentecote = +49 days Whitmonday / Pfingstmontag / Lundi de Pentecote = +50 days Feast of Corpus Christi / Fronleichnam / Fete-Dieu = +60 days Use the offsets shown above to calculate the date of the corresponding feast day as follows: ($year,$month,$day) = Add_Delta_Days(Easter_Sunday($year), $offset)); * `if ($month = Decode_Month($string))' This function takes a string as its argument, which should contain the name of a month *IN THE CURRENTLY SELECTED LANGUAGE* (see further below for details about the multi-language support of this package), or any uniquely identifying abbreviation of a month's name (i.e., the first few letters), and returns the corresponding number (1..12) upon a successful match, or "0" otherwise (therefore, the return value can also be used as the conditional expression in an "if" statement). Note that the input string may not contain any other characters which do not pertain to the month's name, especially no leading or trailing whitespace. Note also that matching is performed in a case-insensitive manner (this may depend on the "locale" setting on your current system, though!) With "English" as the currently selected language (which is the default), the following examples will all return the value "9": $month = Decode_Month("s"); $month = Decode_Month("Sep"); $month = Decode_Month("septemb"); $month = Decode_Month("September"); * `if ($dow = Decode_Day_of_Week($string))' This function takes a string as its argument, which should contain the name of a day of week *IN THE CURRENTLY SELECTED LANGUAGE* (see further below for details about the multi-language support of this package), or any uniquely identifying abbreviation of the name of a day of week (i.e., the first few letters), and returns the corresponding number (1..7) upon a successful match, or "0" otherwise (therefore, the return value can also be used as the conditional expression in an "if" statement). Note that the input string may not contain any other characters which do not pertain to the name of the day of week, especially no leading or trailing whitespace. Note also that matching is performed in a case-insensitive manner (this may depend on the "locale" setting on your current system, though!) With "English" as the currently selected language (which is the default), the following examples will all return the value "3": $dow = Decode_Day_of_Week("w"); $dow = Decode_Day_of_Week("Wed"); $dow = Decode_Day_of_Week("wednes"); $dow = Decode_Day_of_Week("Wednesday"); * `if ($lang = Decode_Language($string))' This function takes a string as its argument, which should contain the name of one of the languages supported by this package (*IN THIS VERY LANGUAGE ITSELF*), or any uniquely identifying abbreviation of the name of a language (i.e., the first few letters), and returns its corresponding internal number (1..7 in the original distribution) upon a successful match, or "0" otherwise (therefore, the return value can also be used as the conditional expression in an "if" statement). Note that the input string may not contain any other characters which do not pertain to the name of a language, especially no leading or trailing whitespace. Note also that matching is performed in a case-insensitive manner (this may depend on the "locale" setting on your current system, though!) The original distribution supports the following seven languages: English ==> 1 (default) Français (French) ==> 2 Deutsch (German) ==> 3 Español (Spanish) ==> 4 Português (Portuguese) ==> 5 Nederlands (Dutch) ==> 6 Italiano (Italian) ==> 7 See the section "How to install additional languages" in the file "INSTALL.txt" in this distribution for how to add more languages to this package. In the original distribution (no other languages installed), the following examples will all return the value "3": $lang = Decode_Language("d"); $lang = Decode_Language("de"); $lang = Decode_Language("Deutsch"); Note that you may not be able to enter the special international characters in some of the languages' names over the keyboard directly on some systems. This should never be a problem, though; just enter an abbreviation of the name of the language consisting of the first few letters up to the character before the first special international character. * `if (($year,$month,$day) = Decode_Date_EU($string))' This function scans a given string and tries to parse any date which might be embedded in it. The function returns an empty list if it can't successfully extract a valid date from its input string, or else it returns the date found. The function accepts almost any format, as long as the date is given in the european order (hence its name) day-month-year. Thereby, zero or more *NON-NUMERIC* characters may *PRECEDE* the day and *FOLLOW* the year. Moreover, zero or more *NON-ALPHANUMERIC* characters are permitted *BETWEEN* these three items (i.e., between day and month and between month and year). The month may be given either numerically (i.e., a number from "1" to "12"), or alphanumerically, i.e., as the name of the month *IN THE CURRENTLY SELECTED LANGUAGE*, or any uniquely identifying abbreviation thereof. (See further below for details about the multi-language support of this package!) If the year is given as one or two digits only (i.e., if the year is less than 100), it is mapped to the window "`1970 - 2069'" as follows: 0 Less_Than_Special_Sequence= $year Less_Than_Special_Sequence 70 ==> $year += 2000; 70 Less_Than_Special_Sequence= $year Less_Than_Special_Sequence 100 ==> $year += 1900; If the day, month and year are all given numerically but *WITHOUT* any delimiting characters between them, this string of digits will be mapped to the day, month and year as follows: Length: Mapping: 3 dmy 4 dmyy 5 dmmyy 6 ddmmyy 7 dmmyyyy 8 ddmmyyyy (Where "d" stands for "day", "m" stands for "month" and "y" stands for "year".) All other strings consisting purely of digits (without any intervening delimiters) are rejected, i.e., not recognized. Examples: "3.1.64" "3 1 64" "03.01.64" "03/01/64" "3. Jan 1964" "Birthday: 3. Jan '64 in Backnang/Germany" "03-Jan-64" "3.Jan1964" "3Jan64" "030164" "3ja64" "3164" Experiment! (See the corresponding example applications in the "examples" subdirectory of this distribution in order to do so.) * `if (($year,$month,$day) = Decode_Date_US($string))' This function scans a given string and tries to parse any date which might be embedded in it. The function returns an empty list if it can't successfully extract a valid date from its input string, or else it returns the date found. The function accepts almost any format, as long as the date is given in the U.S. american order (hence its name) month-day-year. Thereby, zero or more *NON-ALPHANUMERIC* characters may *PRECEDE* and *FOLLOW* the month (i.e., precede the month and separate it from the day which follows behind). Moreover, zero or more *NON-NUMERIC* characters are permitted *BETWEEN* the day and the year, as well as *AFTER* the year. The month may be given either numerically (i.e., a number from "1" to "12"), or alphanumerically, i.e., as the name of the month *IN THE CURRENTLY SELECTED LANGUAGE*, or any uniquely identifying abbreviation thereof. (See further below for details about the multi-language support of this package!) If the year is given as one or two digits only (i.e., if the year is less than 100), it is mapped to the window "`1970 - 2069'" as follows: 0 Less_Than_Special_Sequence= $year Less_Than_Special_Sequence 70 ==> $year += 2000; 70 Less_Than_Special_Sequence= $year Less_Than_Special_Sequence 100 ==> $year += 1900; If the month, day and year are all given numerically but *WITHOUT* any delimiting characters between them, this string of digits will be mapped to the month, day and year as follows: Length: Mapping: 3 mdy 4 mdyy 5 mddyy 6 mmddyy 7 mddyyyy 8 mmddyyyy (Where "m" stands for "month", "d" stands for "day" and "y" stands for "year".) All other strings consisting purely of digits (without any intervening delimiters) are rejected, i.e., not recognized. If only the day and the year form a contiguous string of digits, they will be mapped as follows: Length: Mapping: 2 dy 3 dyy 4 ddyy 5 dyyyy 6 ddyyyy (Where "d" stands for "day" and "y" stands for "year".) Examples: "1 3 64" "01/03/64" "Jan 3 '64" "Jan 3 1964" "===> January 3rd 1964 (birthday)" "Jan31964" "Jan364" "ja364" "1364" Experiment! (See the corresponding example applications in the "examples" subdirectory of this distribution in order to do so.) * `$date = Compress($year,$month,$day);' This function encodes a date in 16 bits, which is the value being returned. The encoding scheme is as follows: Bit number: FEDCBA9 8765 43210 Contents: yyyyyyy mmmm ddddd (Where the "yyyyyyy" contain the number of the year, "mmmm" the number of the month and "ddddd" the number of the day.) The function returns "0" if the given input values do not represent a valid date. Therefore, the return value of this function can also be used as the conditional expression in an "if" statement, in order to check wether the given input values constitute a valid date). Through this special encoding scheme, it is possible to *COMPARE* compressed dates for equality and order (less than/greater than) *WITHOUT* any previous *DECODING*! Note however that contiguous dates do *NOT* necessarily have contiguous compressed representations! I.e., incrementing the compressed representation of a date *MAY OR MAY NOT* yield a valid new date! Note also that this function can only handle dates within one century. This century can be chosen at random by defining a base century and year (also called the "epoch"). In the original distribution of this package, the base century is set to "1900" and the base year to "70" (which is standard on UNIX systems). This allows this function to handle dates from "1970" up to "2069". If the given year is equal to, say, "95", this package will automatically assume that you really mean "1995" instead. However, if you specify a year number which is *SMALLER* than 70, like "64", for instance, this package will assume that you really mean "2064". You are not confined to two-digit (abbreviated) year numbers, though. The function also accepts "full-length" year numbers, provided that they lie in the supported range (i.e., from "1970" to "2069", in the original configuration of this package). Note that this function is maintained mainly for backward compatibility, and that its use is not recommended. * `if (($century,$year,$month,$day) = Uncompress($date))' This function decodes dates that were encoded previously using the function "`Compress()'". It returns the century, year, month and day of the date encoded in "`$date'" if "`$date'" represents a valid date, or an empty list otherwise. The year returned in "$year" is actually a two-digit year number (i.e., the year number taken modulo 100), and only the expression "`$century + $year'" yields the "full-length" year number (for example, `1900 + 95 = 1995'). Note that this function is maintained mainly for backward compatibility, and that its use is not recommended. * `if (check_compressed($date))' This function returns "true" ("1") if the given input value constitutes a valid compressed date, and "false" ("0") otherwise. Note that this function is maintained mainly for backward compatibility, and that its use is not recommended. * `$string = Compressed_to_Text($date);' This function returns a string of fixed length (always 9 characters long) containing a textual representation of the compressed date encoded in "`$date'". This string has the form "dd-Mmm-yy", where "dd" is the two-digit number of the day, "Mmm" are the first three letters of the name of the month in the currently selected language (see further below for details about the multi-language support of this package), and "yy" is the two-digit year number (i.e., the year number taken modulo 100). If "`$date'" does not represent a valid date, the string "??-???-??" is returned instead. Note that this function is maintained mainly for backward compatibility, and that its use is not recommended. * `$string = Date_to_Text($year,$month,$day);' This function returns a string containing a textual representation of the given date of the form "www dd-Mmm-yyyy", where "www" are the first three letters of the name of the day of week in the currently selected language, or a special abbreviation, if special abbreviations have been defined for the currently selected language (see further below for details about the multi-language support of this package), "dd" is the day (one or two digits), "Mmm" are the first three letters of the name of the month in the currently selected language, and "yyyy" is the number of the year in full length. If the given input values do not constitute a valid date, a fatal "not a valid date" error occurs. (See the section "RECIPES" near the end of this document for a code snippet for how to print dates in any format you like.) * `$string = Date_to_Text_Long($year,$month,$day);' This function returns a string containing a textual representation of the given date roughly of the form "Wwwwww, dd Mmmmmm yyyy", where "Wwwwww" is the name of the day of week in the currently selected language (see further below for details about the multi-language support of this package), "dd" is the day (one or two digits), "Mmmmmm" is the name of the month in the currently selected language, and "yyyy" is the number of the year in full length. The exact format of the output string depends on the currently selected language. In the original distribution of this package, these formats are defined as follows: 1 English : "Wwwwww, Mmmmmm ddth yyyy" 2 French : "Wwwwww, le dd Mmmmmm yyyy" 3 German : "Wwwwww, den dd. Mmmmmm yyyy" 4 Spanish : "Wwwwww, dd de Mmmmmm de yyyy" 5 Portuguese : "Wwwwww, dia dd de Mmmmmm de yyyy" 6 Dutch : "Wwwwww, dd. Mmmmmm yyyy" 7 Italian : "Wwwwww, dd Mmmmmm yyyy" (You can change these formats in the file "DateCalc.c" before building this module in order to suit your personal preferences.) If the given input values do not constitute a valid date, a fatal "not a valid date" error occurs. (See the section "RECIPES" near the end of this document for an example on how to print dates in any format you like.) * `$string = English_Ordinal($number);' This function returns a string containing the (english) abbreviation of the ordinal number for the given (cardinal) number "`$number'". I.e., 0 => '0th' 10 => '10th' 20 => '20th' 1 => '1st' 11 => '11th' 21 => '21st' 2 => '2nd' 12 => '12th' 22 => '22nd' 3 => '3rd' 13 => '13th' 23 => '23rd' 4 => '4th' 14 => '14th' 24 => '24th' 5 => '5th' 15 => '15th' 25 => '25th' 6 => '6th' 16 => '16th' 26 => '26th' 7 => '7th' 17 => '17th' 27 => '27th' 8 => '8th' 18 => '18th' 28 => '28th' 9 => '9th' 19 => '19th' 29 => '29th' etc. * `$string = Calendar($year,$month);' This function returns a calendar of the given month in the given year (somewhat similar to the UNIX "cal" command), *IN THE CURRENTLY SELECTED LANGUAGE* (see further below for details about the multi-language support of this package). Example: print Calendar(1998,5); This will print: May 1998 Mon Tue Wed Thu Fri Sat Sun 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 * `$string = Month_to_Text($month);' This function returns the name of the given month in the currently selected language (see further below for details about the multi-language support of this package). If the given month lies outside of the valid range from "1" to "12", a fatal "month out of range" error will occur. * `$string = Day_of_Week_to_Text($dow);' This function returns the name of the given day of week in the currently selected language (see further below for details about the multi-language support of this package). If the given day of week lies outside of the valid range from "1" to "7", a fatal "day of week out of range" error will occur. * `$string = Day_of_Week_Abbreviation($dow);' This function returns the special abbreviation of the name of the given day of week, IF such special abbreviations have been defined for the currently selected language (see further below for details about the multi-language support of this package). (In the original distribution of this package, this is only true for Portuguese.) If not, the first three letters of the name of the day of week in the currently selected language are returned instead. If the given day of week lies outside of the valid range from "1" to "7", a fatal "day of week out of range" error will occur. Currently, this table of special abbreviations is only used by the functions "`Date_to_Text()'" and "`Calendar()'", internally. * `$string = Language_to_Text($lang);' This function returns the name of any language supported by this package when the internal number representing that language is given as input. The original distribution supports the following seven languages: 1 ==> English (default) 2 ==> Français (French) 3 ==> Deutsch (German) 4 ==> Español (Spanish) 5 ==> Português (Portuguese) 6 ==> Nederlands (Dutch) 7 ==> Italiano (Italian) See the section "How to install additional languages" in the file "INSTALL.txt" in this distribution for how to add more languages to this package. See the description of the function "`Languages()'" further below to determine how many languages are actually available in a given installation of this package. * `$lang = Language();' * `Language($lang);' * `$oldlang = Language($newlang);' This function can be used to determine which language is currently selected, and to change the selected language. Thereby, each language has a unique internal number. The original distribution contains the following seven languages: 1 ==> English (default) 2 ==> Français (French) 3 ==> Deutsch (German) 4 ==> Español (Spanish) 5 ==> Português (Portuguese) 6 ==> Nederlands (Dutch) 7 ==> Italiano (Italian) See the section "How to install additional languages" in the file "INSTALL.txt" in this distribution for how to add more languages to this package. See the description of the function "`Languages()'" further below to determine how many languages are actually available in a given installation of this package. *BEWARE* that in order for your programs to be portable, you should *NEVER* actually use the internal number of a language in this package *EXPLICITLY*, because the same number could mean different languages on different systems, depending on what languages have been added to any given installation of this package. Therefore, you should always use a statement such as Language(Decode_Language("Name_of_Language")); to select the desired language, and $language = Language_to_Text(Language()); or $old_language = Language_to_Text(Language("Name_of_new_Language")); to determine the (previously) selected language. If the so chosen language is not available in the current installation, this will result in an appropriate error message, instead of silently using the wrong (a random) language (which just happens to have the same internal number in the other installation). Note that in the current implementation of this package, the selected language is a global setting valid for ALL functions that use the names of months, days of week or languages internally, valid for *ALL PROCESSES* using the same copy of the "Date::Calc" shared library in memory! This may have surprising side-effects in a multi-user environment, and even more so when Perl will be capable of multi-threading in some future release. * `$max_lang = Languages();' This function returns the (maximum) number of languages which are currently available in your installation of this package. (This may vary from installation to installation.) See the section "How to install additional languages" in the file "INSTALL.txt" in this distribution for how to add more languages to this package. In the original distribution of this package there are seven built-in languages, therefore the value returned by this function will be "7" if no other languages have been added to your particular installation. * `if (($year,$month,$day) = Decode_Date_EU2($string))' This function is the Perl equivalent of the function "`Decode_Date_EU()'" (implemented in C), included here merely as an example to demonstrate how easy it is to write your own routine in Perl (using regular expressions) adapted to your own special needs, should the necessity arise, and intended primarily as a basis for your own development. In one particular case this Perl version is actually slightly more permissive than its C equivalent, as far as the class of permitted intervening (i.e., delimiting) characters is concerned. (Can you tell the subtle, almost insignificant difference by looking at the code? Or by experimenting? Hint: Try the string "a3b1c64d" with both functions.) * `if (($year,$month,$day) = Decode_Date_US2($string))' This function is the Perl equivalent of the function "`Decode_Date_US()'" (implemented in C), included here merely as an example to demonstrate how easy it is to write your own routine in Perl (using regular expressions) adapted to your own special needs, should the necessity arise, and intended primarily as a basis for your own development. In one particular case this Perl version is actually slightly more permissive than its C equivalent. (Hint: This is the same difference as with the "`Decode_Date_EU()'" and "`Decode_Date_EU2()'" pair of functions.) In a different case, the C version is a little bit more permissive than its Perl equivalent. (Can you tell the difference by looking at the code? Or by experimenting? Hint: Try the string "(1/364)" with both functions.) * `if (($year,$month,$day) = Parse_Date($string))' This function is useful for parsing dates as returned by the UNIX "date" command or as found in the headers of e-mail (in order to determine the date at which some e-mail has been sent or received, for instance). Example #1: ($year,$month,$day) = Parse_Date(`/bin/date`); Example #2: while () { if (/^From \S/) { ($year,$month,$day) = Parse_Date($_); ... } ... } The function returns an empty list if it can't extract a valid date from the input string. * `$string = Date::Calc::Version();' This function returns a string with the (numeric) version number of the C library ("DateCalc.c") at the core of this package (which is also (automatically) the version number of the "Calc.xs" file). Note that under all normal circumstances, this version number should be identical with the one found in the Perl variable "`$Date::Calc::VERSION'" (the version number of the "Calc.pm" file). Since this function is not exported, you always have to qualify it explicitly, i.e., "`Date::Calc::Version()'". This is to avoid possible name space conflicts with version functions from other modules. RECIPES ======= 1. How do I compare two dates? Solution #1: use Date::Calc qw( Date_to_Days ); if (Date_to_Days($year1,$month1,$day1) < Date_to_Days($year2,$month2,$day2)) if (Date_to_Days($year1,$month1,$day1) <= Date_to_Days($year2,$month2,$day2)) if (Date_to_Days($year1,$month1,$day1) > Date_to_Days($year2,$month2,$day2)) if (Date_to_Days($year1,$month1,$day1) >= Date_to_Days($year2,$month2,$day2)) if (Date_to_Days($year1,$month1,$day1) == Date_to_Days($year2,$month2,$day2)) if (Date_to_Days($year1,$month1,$day1) != Date_to_Days($year2,$month2,$day2)) $cmp = (Date_to_Days($year1,$month1,$day1) <=> Date_to_Days($year2,$month2,$day2)); Solution #2: use Date::Calc qw( Delta_Days ); if (Delta_Days($year1,$month1,$day1, $year2,$month2,$day2) > 0) if (Delta_Days($year1,$month1,$day1, $year2,$month2,$day2) >= 0) if (Delta_Days($year1,$month1,$day1, $year2,$month2,$day2) < 0) if (Delta_Days($year1,$month1,$day1, $year2,$month2,$day2) <= 0) if (Delta_Days($year1,$month1,$day1, $year2,$month2,$day2) == 0) if (Delta_Days($year1,$month1,$day1, $year2,$month2,$day2) != 0) 2. How do I check wether a given date lies within a certain range of dates? use Date::Calc qw( Date_to_Days ); $lower = Date_to_Days($year1,$month1,$day1); $upper = Date_to_Days($year2,$month2,$day2); $date = Date_to_Days($year,$month,$day); if (($date >= $lower) && ($date <= $upper)) { # ok } else { # not ok } 3. How do I verify wether someone has a certain age? use Date::Calc qw( Decode_Date_EU Today leap_year Delta_Days ); $date = ; # get birthday ($year1,$month1,$day1) = Decode_Date_EU($date); ($year2,$month2,$day2) = Today(); if (($day1 == 29) && ($month1 == 2) && !leap_year($year2)) { $day1--; } if ( (($year2 - $year1) > 18) || ( (($year2 - $year1) == 18) && (Delta_Days($year2,$month1,$day1, $year2,$month2,$day2) >= 0) ) ) { print "Ok - you are over 18.\n"; } else { print "Sorry - you aren't 18 yet!\n"; } 4. How do I calculate the number of the week of month the current date lies in? For example: April 1998 Mon Tue Wed Thu Fri Sat Sun 1 2 3 4 5 = week #1 6 7 8 9 10 11 12 = week #2 13 14 15 16 17 18 19 = week #3 20 21 22 23 24 25 26 = week #4 27 28 29 30 = week #5 Solution: use Date::Calc qw( Today Day_of_Week ); ($year,$month,$day) = Today(); $week = int(($day + Day_of_Week($year,$month,1) - 2) / 7) + 1; 5. How do I calculate wether a given date is the 1st, 2nd, 3rd, 4th or 5th of that day of week in the given month? For example: October 2000 Mon Tue Wed Thu Fri Sat Sun 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 Is Sunday, the 15th of October 2000, the 1st, 2nd, 3rd, 4th or 5th Sunday of that month? Solution: use Date::Calc qw( Day_of_Week Delta_Days Nth_Weekday_of_Month_Year Date_to_Text_Long English_Ordinal Day_of_Week_to_Text Month_to_Text ); ($year,$month,$day) = (2000,10,15); $dow = Day_of_Week($year,$month,$day); $n = int( Delta_Days( Nth_Weekday_of_Month_Year($year,$month,$dow,1), $year,$month,$day) / 7) + 1; printf("%s is the %s %s in %s %d.\n", Date_to_Text_Long($year,$month,$day), English_Ordinal($n), Day_of_Week_to_Text($dow), Month_to_Text($month), $year); This prints: Sunday, October 15th 2000 is the 3rd Sunday in October 2000. 6. How do I calculate the date of the Wednesday of the same week as the current date? Solution #1: use Date::Calc qw( Today Day_of_Week Add_Delta_Days ); $searching_dow = 3; # 3 = Wednesday @today = Today(); $current_dow = Day_of_Week(@today); @date = Add_Delta_Days(@today, $searching_dow - $current_dow); Solution #2: use Date::Calc qw( Today Add_Delta_Days Monday_of_Week Week_of_Year ); $searching_dow = 3; # 3 = Wednesday @today = Today(); @date = Add_Delta_Days( Monday_of_Week( Week_of_Year(@today) ), $searching_dow - 1 ); Solution #3: use Date::Calc qw( Standard_to_Business Today Business_to_Standard ); @business = Standard_to_Business(Today()); $business[2] = 3; # 3 = Wednesday @date = Business_to_Standard(@business); 7. How can I add a week offset to a business date (including across year boundaries)? use Date::Calc qw( Business_to_Standard Add_Delta_Days Standard_to_Business ); @temp = Business_to_Standard($year,$week,$dow); @temp = Add_Delta_Days(@temp, $week_offset * 7); ($year,$week,$dow) = Standard_to_Business(@temp); 8. How do I calculate the last and the next Saturday for any given date? use Date::Calc qw( Today Day_of_Week Add_Delta_Days Day_of_Week_to_Text Date_to_Text ); $searching_dow = 6; # 6 = Saturday @today = Today(); $current_dow = Day_of_Week(@today); if ($searching_dow == $current_dow) { @prev = Add_Delta_Days(@today,-7); @next = Add_Delta_Days(@today,+7); } else { if ($searching_dow > $current_dow) { @next = Add_Delta_Days(@today, $searching_dow - $current_dow); @prev = Add_Delta_Days(@next,-7); } else { @prev = Add_Delta_Days(@today, $searching_dow - $current_dow); @next = Add_Delta_Days(@prev,+7); } } $dow = Day_of_Week_to_Text($searching_dow); print "Today is: ", ' ' x length($dow), Date_to_Text(@today), "\n"; print "Last $dow was: ", Date_to_Text(@prev), "\n"; print "Next $dow will be: ", Date_to_Text(@next), "\n"; This will print something like: Today is: Sun 12-Apr-1998 Last Saturday was: Sat 11-Apr-1998 Next Saturday will be: Sat 18-Apr-1998 9. How can I calculate the last business day (payday!) of a month? Solution #1 (holidays *NOT* taken into account): use Date::Calc qw( Days_in_Month Day_of_Week Add_Delta_Days ); $day = Days_in_Month($year,$month); $dow = Day_of_Week($year,$month,$day); if ($dow > 5) { ($year,$month,$day) = Add_Delta_Days($year,$month,$day, 5-$dow); } Solution #2 (holidays taken into account): This solution expects a multi-dimensional array "`@holiday'", which contains all holidays, as follows: "`$holiday[$year][$month][$day] = 1;'". (See the description of the function "`Easter_Sunday()'" further above for how to calculate the moving (variable) christian feast days!) Days which are not holidays remain undefined or should have a value of zero in this array. use Date::Calc qw( Days_in_Month Add_Delta_Days Day_of_Week ); $day = Days_in_Month($year,$month); while (1) { while ($holiday[$year][$month][$day]) { ($year,$month,$day) = Add_Delta_Days($year,$month,$day, -1); } $dow = Day_of_Week($year,$month,$day); if ($dow > 5) { ($year,$month,$day) = Add_Delta_Days($year,$month,$day, 5-$dow); } else { last; } } 10. How do I convert a MS Visual Basic "DATETIME" value into its date and time constituents? use Date::Calc qw( Add_Delta_DHMS Date_to_Text ); $datetime = "35883.121653"; ($Dd,$Dh,$Dm,$Ds) = ($datetime =~ /^(\d+)\.(\d\d)(\d\d)(\d\d)$/); ($year,$month,$day, $hour,$min,$sec) = Add_Delta_DHMS(1900,1,1, 0,0,0, $Dd,$Dh,$Dm,$Ds); printf("The given date is %s %02d:%02d:%02d\n", Date_to_Text($year,$month,$day), $hour, $min, $sec); This prints: The given date is Tue 31-Mar-1998 12:16:53 11. How can I send a reminder to members of a group on the day before a meeting which occurs every first Friday of a month? use Date::Calc qw( Today Date_to_Days Add_Delta_YMD Nth_Weekday_of_Month_Year ); ($year,$month,$day) = Today(); $tomorrow = Date_to_Days($year,$month,$day) + 1; $dow = 5; # 5 = Friday $n = 1; # 1 = First of that day of week $meeting_this_month = Date_to_Days( Nth_Weekday_of_Month_Year($year,$month,$dow,$n) ); ($year,$month,$day) = Add_Delta_YMD($year,$month,$day, 0,1,0); $meeting_next_month = Date_to_Days( Nth_Weekday_of_Month_Year($year,$month,$dow,$n) ); if (($tomorrow == $meeting_this_month) || ($tomorrow == $meeting_next_month)) { # Send reminder e-mail! } 12. How can I print a date in a different format than provided by the functions "`Date_to_Text()'", "`Date_to_Text_Long()'" or "`Compressed_to_Text()'"? use Date::Calc qw( Today Day_of_Week_to_Text Day_of_Week Month_to_Text English_Ordinal ); ($year,$month,$day) = Today(); For example with leading zeros for the day: "Fri 03-Jan-1964" printf("%.3s %02d-%.3s-%d\n", Day_of_Week_to_Text(Day_of_Week($year,$month,$day)), $day, Month_to_Text($month), $year); For example in U.S. american format: "April 12th, 1998" $string = sprintf("%s %s, %d", Month_to_Text($month), English_Ordinal($day), $year); (See also `perlfunc(1)' in this node and/or `perlfunc(1)' in this node!) 13. How can I iterate through a range of dates? use Date::Calc qw( Delta_Days Add_Delta_Days ); @start = (1999,5,27); @stop = (1999,6,1); $j = Delta_Days(@start,@stop); for ( $i = 0; $i <= $j; $i++ ) { @date = Add_Delta_Days(@start,$i); printf("%4d/%02d/%02d\n", @date); } Note that the loop can be improved; see also the recipe below. 14. How can I create a (Perl) list of dates in a certain range? use Date::Calc qw( Delta_Days Add_Delta_Days Date_to_Text ); sub date_range { my(@date) = (@_)[0,1,2]; my(@list); my($i); $i = Delta_Days(@_); while ($i-- >= 0) { push( @list, [ @date ] ); @date = Add_Delta_Days(@date, 1) if ($i >= 0); } return(@list); } @range = &date_range(1999,11,3, 1999,12,24); # in chronological order foreach $date (@range) { print Date_to_Text(@{$date}), "\n"; } Note that you probably shouldn't use this one, because it is much more efficient to iterate through all the dates (as shown in the recipe immediately above) than to construct such an array and then to loop through it. Also, it is much more space-efficient not to create this array. 15. How can I calculate the difference in days between dates, but without counting Saturdays and Sundays? sub Delta_Business_Days { my(@date1) = (@_)[0,1,2]; my(@date2) = (@_)[3,4,5]; my($minus,$result,$dow1,$dow2,$diff,$temp); $minus = 0; $result = Delta_Days(@date1,@date2); if ($result != 0) { if ($result < 0) { $minus = 1; $result = -$result; $dow1 = Day_of_Week(@date2); $dow2 = Day_of_Week(@date1); } else { $dow1 = Day_of_Week(@date1); $dow2 = Day_of_Week(@date2); } $diff = $dow2 - $dow1; $temp = $result; if ($diff != 0) { if ($diff < 0) { $diff += 7; } $temp -= $diff; $dow1 += $diff; if ($dow1 > 6) { $result--; if ($dow1 > 7) { $result--; } } } if ($temp != 0) { $temp /= 7; $result -= ($temp << 1); } } if ($minus) { return -$result; } else { return $result; } } This solution is probably of little practical value, however, because it doesn't take legal holidays into account. SEE ALSO ======== perl(1), perlfunc(1), perlsub(1), perlmod(1), perlxs(1), perlxstut(1), perlguts(1). news:news.answers "Calendar FAQ, v. 1.9 (modified 25 Apr 1998) Part 1/3" news:news.answers "Calendar FAQ, v. 1.9 (modified 25 Apr 1998) Part 2/3" news:news.answers "Calendar FAQ, v. 1.9 (modified 25 Apr 1998) Part 3/3" http://www.math.uio.no/faq/calendars/faq.html http://www.pip.dknet.dk/~pip10160/calendar.html (All authored by Claus Tondering ) LIMITATIONS =========== In the current implementation of this package, the selected language is stored in a global variable. Therefore, when you are using a threaded Perl, this may cause undesired side effects (of one thread always selecting the language for *ALL OTHER* threads as well). VERSION ======= This man page documents "Date::Calc" version 4.3. AUTHOR ====== Steffen Beyer Ainmillerstr. 5 / App. 513 D-80801 Munich Germany mailto:sb@engelschall.com http://www.engelschall.com/u/sb/download/ *Please contact me by e-mail whenever possible!* COPYRIGHT ========= Copyright (c) 1995 - 2000 by Steffen Beyer. All rights reserved. LICENSE ======= This package is free software; you can redistribute it and/or modify it under the same terms as Perl itself, i.e., under the terms of the "Artistic License" or the "GNU General Public License". The C library at the core of this Perl module can additionally be redistributed and/or modified under the terms of the "GNU Library General Public License". Please refer to the files "Artistic.txt", "GNU_GPL.txt" and "GNU_LGPL.txt" in this distribution for details! DISCLAIMER ========== This package is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the "GNU General Public License" for more details.