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Advanced Date/Time Handling with PHP

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Anis Berejeb

This document provides an overview of advanced date and time handling in PHP, including: - Setting default timezones and parsing date strings - Modifying dates and times using objects and intervals - Working with timezones and the timezone database - Iterating over periods defined by start date, interval, and end date

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Welcome! Advanced Date/Time Handling ZendCon - Santa Clara, US - Nov 2nd, 2010 Derick Rethans - derick@php.net - twitter: @derickr http://derickrethans.nl/talks.html http://joind.in/2232
About Me Derick Rethans ¡ñ Dutchman living in London ¡ñ PHP development ¡ñ Author of the mcrypt, input_filter, dbus, translit and date/time extensions ¡ñ Author of Xdebug ¡ñ Contributor to the Apache Zeta Components Incubator project (formerly eZ Components) ¡ñ Freelancer doing PHP (internals) development
Problems Timezones ¡ñ Most places have whole-hour timezone offsets ¡ñ Some places change timezones during the year ¡ñ One identifier can mean different zones: PST: Pacific Standard Time, Pakistan Standard Time EST: Eastern Standard Time (USA), Eastern Standard Time (Australia) and Eastern Brazil Standard Time
Timezone Support ¡ñ Bundled timezone database with 564 zones ¡ñ Not dependent on timezone abbreviations ¡ñ Timezones have the format: Continent/Location or Continent/Location/Sublocation - Like: Europe/Amsterdam, America/Indiana/Knox
Changing Timezone Definitions ¡ñ An updated database is released about 20 times a year. ¡ñ Some of the changes are very sudden. ¡ñ PHP releases will therefore often have an outdated version. ¡ñ The PECL extension timezonedb provides a drop in replacement for the timezone database. ¡ñ pecl install timezonedb
Default Timezones Setting a default timezone: <?php date_default_timezone_set("Europe/Oslo"); $ts = new DateTime("1978-12-22 09:15"); echo $ts->format("e"); ?> Getting a default timezone: <?php $default_identifier = date_default_timezone_get(); echo $default_identifier; ?> Default timezone is 'guessed' in the following order: ¡ñ date_default_timezone_set() value ¡ñ TZ environment variable ¡ñ php.ini's date.timezone setting ¡ñ System's rendering of timezone abbreviation
Problems with timestamps and timezones <?php $date = strtotime( '2010-03-07 20:48:21 America/Toronto' ); echo date( 'Y-m-d', $date ), "n"; ?> Explanation: 2010-03-07 20:48:21 America/Toronto 1268012901 string is turned into a number 2010-03-08 01:48:21 Europe/London number is converted to a date/time string using the default timezone
Parsing Dates Parsing strings for date time information by instantiating a DateTime object: <?php $dt = new DateTime("2010-03-08 08:43:57"); ?> This function will not return the timestamp as an integer, but instead returns a DateTime object which is a wrapper around a 64 bit integer, which you can access (as string) through: <?php $dt = new DateTime("2010-03-08 08:44:12"); echo $dt->format( 'U' ), "n"; ?> The DateTime class is what you can do the really cool things with.
Parsing Dates "22apr2006 8:36:14 #^ Europe/Oslo CEST" "22apr2006 8:36:14 #^ Europe/Oslo CEST" "22apr2006 8:36:14 Europe/Oslo CEST" "22apr2006 8:36:14 Europe/Oslo CEST" Parsing strings with the date_parse() function: <?php $date = "22apr2006 8:36:14.43 #^ Europe/Oslo CEST"; $t = date_parse( $date ); echo $t['year'], '-', $t['month'], '-', $t['day'], " "; echo $t['hour'], ':', $t['minute'], ':', $t['second'] + $t['fraction'], " "; echo $t['tz_id'], "n"; if ( $t['warning_count'] ) echo "Warnings:n"; foreach( $t['warnings'] as $pos => $message ) echo "- $message @$posn"; if ( $t['error_count'] ) echo "Errors:n"; foreach( $t['errors'] as $pos => $message ) echo "- $message @$posn";
Parsing Dates 08/03/10 08/03/10 August 3rd, 2010 (default) 08/03/10 2008 March 10 08/03/10 8 March 2010
Parsing Dates With user-defined format Creating strings with the date_create_from_format() function: <?php $date = "06/08/04"; echo DateTime::createFromFormat( '!d/m/y', $date )->format( DateTime::ISO8601 ), "n"; ?> Parsing strings with the date_parse_from_format() function: <?php $date = "06/08/04"; print_r( date_parse_from_format( '!y*d*m', $date ) ); ?> Example: Pattern String Y M D !y*d*m 06/08/04 false false false !y*d*m 06/08/04 1970 01 01 !y*d*m 06/08/04 2006 01 01 !y*d*m 06/08/04 2006 01 08 !y*d*m 06/08/04 2006 04 08
Modifying Dates Modifying dates and times: <?php date_default_timezone_set("Europe/London"); $ts = new DateTime("2010-03-08 15:53:55"); $ts->modify("+2 days"); $ts->modify("Friday +3 weeks"); $ts->modify("next friday"); ?> Result: Mon, 08 Mar 2010 15:53:55 +0000 Wed, 10 Mar 2010 15:53:55 +0000 Fri, 02 Apr 2010 15:53:55 +0100 Fri, 09 Apr 2010 15:53:55 +0100
Using Timezones The Timezone Object Creating a timezone resource: <?php $tz = new DateTimeZone("Asia/Singapore"); ?> Using the timezone when parsing a string with a date representation: <?php $tz = new DateTimeZone("Pacific/Honolulu"); $ts = new DateTime("1978-12-22 09:15", $tz); ?> A passed timezone object does not override a parsed timezone: <?php $tz = new DateTimeZone("Pacific/Honolulu"); $ts2 = new DateTime("1978-12-22 09:15 Europe/London", $tz); echo $ts2->format( DateTime::RFC2822 ); ?>
Using Timezones Changing timezones Using the timezone when parsing a string with a date representation: <?php $tz1 = new DateTimeZone("Pacific/Honolulu"); $tz2 = new DateTimeZone("Australia/Melbourne"); $ts = new DateTime("1978-12-22 09:15", $tz1); echo $ts->getTimezone()->getName(), ': ', $ts->format(DateTime::RFC2822), "<br/>"; $ts->setTimezone($tz2); echo $ts->getTimezone()->getName(), ': ', $ts->format(DateTime::RFC2822), "<br/>"; ?>
Timezones Utilities Transition Times and Location Information <?php $tz = new DateTimeZone("Europe/Berlin"); $trs = $tz->getTransitions( strtotime('1938-01-01 UTC'), strtotime('1948-01-01 UTC') ); foreach ($trs as $tr) { printf("%20s %7d %d %sn", $tr['time'], $tr['offset'], $tr['isdst'], $tr['abbr']); } $loc = $tz->getLocation(); echo 'Info: ', join( ' - ', $loc ), "n";
Timezones Utilities Restricting listing by geographical location Restrict by continent: <?php $ids = timezone_identifiers_list( DateTimeZone::EUROPE ); echo implode( ", ", $ids ); ?> Restrict by country: <?php $ids = timezone_identifiers_list( DateTimeZone::PER_COUNTRY, 'US' ); echo implode( ", ", $ids ); ?>
Intervals (PHP 5.3) Creating an interval <?php // full notation $i = new DateInterval( 'P0003-01-15T06:12:30' ); // abbreviated notation $i = new DateInterval( 'P3DT6H' ); // from a difference $d1 = new DateTime(); $d2 = new DateTime( "2010-10-10 10:10 Europe/Amsterdam" ); $i = $d1->diff( $d2 ); // displaying the difference echo $i->format( '%a days, %h hours, %i minutes' ), "n"; ?> <?php // create from string $i = DateInterval::createFromDateString( "next weekday" ); ?>
Intervals (PHP 5.3) Applying an interval <?php $d = new DateTime( 'August 27th, 2009' ); echo $d->format( "l Y-m-dn" ); $i = DateInterval::createFromDateString( "next weekday" ); echo $d->add( $i )->format( "l Y-m-dn" ); echo $d->add( $i )->format( "l Y-m-dn" ); $i = DateInterval::createFromDateString( "3 months 10 days" ); echo $d->sub( $i )->format( "l Y-m-dn" ); ?> Result: Thursday 2009-08-27 Friday 2009-08-28 Monday 2009-08-31 Thursday 2009-05-21
Relative Time "previous month" / "next month" <?php $date = new DateTime( '2010-01-31 15:48:21' ); echo $date->modify( 'next month' )->format( 'Y-m-d' ), "n"; ?> Explanation: 2010-01-31 15:48:21 2010-02-31 15:48:21 "next month" increases month number by 1 2010-03-03 15:48:21 February only has 28 days, so days are overflown into the next month
Relative Time "first day next month" <?php $date = new DateTime( '2010-01-31 15:48:21' ); echo $date->modify( 'first day next month' )->format( 'Y-m-d' ), "n"; ?> Explanation: 2010-01-31 15:48:21 2010-02-31 15:48:21 "next month" increases month number by 1 2010-03-03 15:48:21 February only has 28 days, so days are overflown into the next month 2010-03-04 15:48:21 "first day" adds one more day
Relative Time "first day *of* next month" <?php $date = new DateTime( '2010-01-31 15:48:21' ); echo $date->modify( 'first day of next month' )->format( 'Y-m-d' ), "n"; ?> Explanation: 2010-01-31 15:48:21 2010-02-31 15:48:21 "next month" increases month number by 1 2010-02-01 15:48:21 "first day of" resets the day number to 1
Relative Time "last day of third month" <?php $date = new DateTime( '2010-01-31 15:48:21' ); echo $date->modify( 'last day of third month' )->format( 'Y-m-d' ), "n"; ?> Explanation: 2010-01-31 15:48:21 2010-04-31 15:48:21 "third month" increases month number by 3 2010-05-00 15:48:21 "last day of" resets the day number to 0 and increases the month number by 1 2010-04-30 15:48:21 Day count is less than 1, so the algorithm corrects this to a proper date
Periods (PHP 5.3) Initializing a period <?php // start, interval and count $db = new DateTime( '2008-07-31' ) ; $di = DateInterval::createFromDateString( 'next weekday' ); $p = new DatePeriod( $db, $di, 3 ); // start, interval and end $de = new DateTime ( '2008-08-05' ); $p = new DatePeriod( $db, $di, $de ); // ISO 8601 string $s = "2008-10-04T20:56:18Z/P0000-00-20T03:15:54/2008-12-22T00:00:00Z"; $p = new DatePeriod( $s ); ?>
Periods (PHP 5.3) Iterating over a period <?php $db = new DateTime( '2008-12-31' ); $de = new DateTime( '2009-12-31' ); $di = DateInterval::createFromDateString( 'third tuesday of next month' ); $dp = new DatePeriod( $db, $di, $de, DatePeriod::EXCLUDE_START_DATE ); foreach ( $dp as $dt ) { echo $dt->format( "F jSn" ); } ?>
php|architect's guide to Date/Time handling
Resources ¡ñ This presentation: http://derickrethans.nl/talks.html ¡ñ World timezones: http://www.worldtimezone.com/index24.php ¡ñ Geonames: http://www.geonames.org/ ¡ñ Questions?: derick@php.net
Thanks! Derick Rethans - derick@php.net - twitter: @derickr http://derickrethans.nl/talks.html http://joind.in/2232

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Advanced Date/Time Handling with PHP

  • 1. Welcome! Advanced Date/Time Handling ZendCon - Santa Clara, US - Nov 2nd, 2010 Derick Rethans - derick@php.net - twitter: @derickr http://derickrethans.nl/talks.html http://joind.in/2232
  • 2. About Me Derick Rethans ¡ñ Dutchman living in London ¡ñ PHP development ¡ñ Author of the mcrypt, input_filter, dbus, translit and date/time extensions ¡ñ Author of Xdebug ¡ñ Contributor to the Apache Zeta Components Incubator project (formerly eZ Components) ¡ñ Freelancer doing PHP (internals) development
  • 3. Problems Timezones ¡ñ Most places have whole-hour timezone offsets ¡ñ Some places change timezones during the year ¡ñ One identifier can mean different zones: PST: Pacific Standard Time, Pakistan Standard Time EST: Eastern Standard Time (USA), Eastern Standard Time (Australia) and Eastern Brazil Standard Time
  • 4. Timezone Support ¡ñ Bundled timezone database with 564 zones ¡ñ Not dependent on timezone abbreviations ¡ñ Timezones have the format: Continent/Location or Continent/Location/Sublocation - Like: Europe/Amsterdam, America/Indiana/Knox
  • 5. Changing Timezone Definitions ¡ñ An updated database is released about 20 times a year. ¡ñ Some of the changes are very sudden. ¡ñ PHP releases will therefore often have an outdated version. ¡ñ The PECL extension timezonedb provides a drop in replacement for the timezone database. ¡ñ pecl install timezonedb
  • 6. Default Timezones Setting a default timezone: <?php date_default_timezone_set("Europe/Oslo"); $ts = new DateTime("1978-12-22 09:15"); echo $ts->format("e"); ?> Getting a default timezone: <?php $default_identifier = date_default_timezone_get(); echo $default_identifier; ?> Default timezone is 'guessed' in the following order: ¡ñ date_default_timezone_set() value ¡ñ TZ environment variable ¡ñ php.ini's date.timezone setting ¡ñ System's rendering of timezone abbreviation
  • 7. Problems with timestamps and timezones <?php $date = strtotime( '2010-03-07 20:48:21 America/Toronto' ); echo date( 'Y-m-d', $date ), "n"; ?> Explanation: 2010-03-07 20:48:21 America/Toronto 1268012901 string is turned into a number 2010-03-08 01:48:21 Europe/London number is converted to a date/time string using the default timezone
  • 8. Parsing Dates Parsing strings for date time information by instantiating a DateTime object: <?php $dt = new DateTime("2010-03-08 08:43:57"); ?> This function will not return the timestamp as an integer, but instead returns a DateTime object which is a wrapper around a 64 bit integer, which you can access (as string) through: <?php $dt = new DateTime("2010-03-08 08:44:12"); echo $dt->format( 'U' ), "n"; ?> The DateTime class is what you can do the really cool things with.
  • 9. Parsing Dates "22apr2006 8:36:14 #^ Europe/Oslo CEST" "22apr2006 8:36:14 #^ Europe/Oslo CEST" "22apr2006 8:36:14 Europe/Oslo CEST" "22apr2006 8:36:14 Europe/Oslo CEST" Parsing strings with the date_parse() function: <?php $date = "22apr2006 8:36:14.43 #^ Europe/Oslo CEST"; $t = date_parse( $date ); echo $t['year'], '-', $t['month'], '-', $t['day'], " "; echo $t['hour'], ':', $t['minute'], ':', $t['second'] + $t['fraction'], " "; echo $t['tz_id'], "n"; if ( $t['warning_count'] ) echo "Warnings:n"; foreach( $t['warnings'] as $pos => $message ) echo "- $message @$posn"; if ( $t['error_count'] ) echo "Errors:n"; foreach( $t['errors'] as $pos => $message ) echo "- $message @$posn";
  • 10. Parsing Dates 08/03/10 08/03/10 August 3rd, 2010 (default) 08/03/10 2008 March 10 08/03/10 8 March 2010
  • 11. Parsing Dates With user-defined format Creating strings with the date_create_from_format() function: <?php $date = "06/08/04"; echo DateTime::createFromFormat( '!d/m/y', $date )->format( DateTime::ISO8601 ), "n"; ?> Parsing strings with the date_parse_from_format() function: <?php $date = "06/08/04"; print_r( date_parse_from_format( '!y*d*m', $date ) ); ?> Example: Pattern String Y M D !y*d*m 06/08/04 false false false !y*d*m 06/08/04 1970 01 01 !y*d*m 06/08/04 2006 01 01 !y*d*m 06/08/04 2006 01 08 !y*d*m 06/08/04 2006 04 08
  • 12. Modifying Dates Modifying dates and times: <?php date_default_timezone_set("Europe/London"); $ts = new DateTime("2010-03-08 15:53:55"); $ts->modify("+2 days"); $ts->modify("Friday +3 weeks"); $ts->modify("next friday"); ?> Result: Mon, 08 Mar 2010 15:53:55 +0000 Wed, 10 Mar 2010 15:53:55 +0000 Fri, 02 Apr 2010 15:53:55 +0100 Fri, 09 Apr 2010 15:53:55 +0100
  • 13. Using Timezones The Timezone Object Creating a timezone resource: <?php $tz = new DateTimeZone("Asia/Singapore"); ?> Using the timezone when parsing a string with a date representation: <?php $tz = new DateTimeZone("Pacific/Honolulu"); $ts = new DateTime("1978-12-22 09:15", $tz); ?> A passed timezone object does not override a parsed timezone: <?php $tz = new DateTimeZone("Pacific/Honolulu"); $ts2 = new DateTime("1978-12-22 09:15 Europe/London", $tz); echo $ts2->format( DateTime::RFC2822 ); ?>
  • 14. Using Timezones Changing timezones Using the timezone when parsing a string with a date representation: <?php $tz1 = new DateTimeZone("Pacific/Honolulu"); $tz2 = new DateTimeZone("Australia/Melbourne"); $ts = new DateTime("1978-12-22 09:15", $tz1); echo $ts->getTimezone()->getName(), ': ', $ts->format(DateTime::RFC2822), "<br/>"; $ts->setTimezone($tz2); echo $ts->getTimezone()->getName(), ': ', $ts->format(DateTime::RFC2822), "<br/>"; ?>
  • 15. Timezones Utilities Transition Times and Location Information <?php $tz = new DateTimeZone("Europe/Berlin"); $trs = $tz->getTransitions( strtotime('1938-01-01 UTC'), strtotime('1948-01-01 UTC') ); foreach ($trs as $tr) { printf("%20s %7d %d %sn", $tr['time'], $tr['offset'], $tr['isdst'], $tr['abbr']); } $loc = $tz->getLocation(); echo 'Info: ', join( ' - ', $loc ), "n";
  • 16. Timezones Utilities Restricting listing by geographical location Restrict by continent: <?php $ids = timezone_identifiers_list( DateTimeZone::EUROPE ); echo implode( ", ", $ids ); ?> Restrict by country: <?php $ids = timezone_identifiers_list( DateTimeZone::PER_COUNTRY, 'US' ); echo implode( ", ", $ids ); ?>
  • 17. Intervals (PHP 5.3) Creating an interval <?php // full notation $i = new DateInterval( 'P0003-01-15T06:12:30' ); // abbreviated notation $i = new DateInterval( 'P3DT6H' ); // from a difference $d1 = new DateTime(); $d2 = new DateTime( "2010-10-10 10:10 Europe/Amsterdam" ); $i = $d1->diff( $d2 ); // displaying the difference echo $i->format( '%a days, %h hours, %i minutes' ), "n"; ?> <?php // create from string $i = DateInterval::createFromDateString( "next weekday" ); ?>
  • 18. Intervals (PHP 5.3) Applying an interval <?php $d = new DateTime( 'August 27th, 2009' ); echo $d->format( "l Y-m-dn" ); $i = DateInterval::createFromDateString( "next weekday" ); echo $d->add( $i )->format( "l Y-m-dn" ); echo $d->add( $i )->format( "l Y-m-dn" ); $i = DateInterval::createFromDateString( "3 months 10 days" ); echo $d->sub( $i )->format( "l Y-m-dn" ); ?> Result: Thursday 2009-08-27 Friday 2009-08-28 Monday 2009-08-31 Thursday 2009-05-21
  • 19. Relative Time "previous month" / "next month" <?php $date = new DateTime( '2010-01-31 15:48:21' ); echo $date->modify( 'next month' )->format( 'Y-m-d' ), "n"; ?> Explanation: 2010-01-31 15:48:21 2010-02-31 15:48:21 "next month" increases month number by 1 2010-03-03 15:48:21 February only has 28 days, so days are overflown into the next month
  • 20. Relative Time "first day next month" <?php $date = new DateTime( '2010-01-31 15:48:21' ); echo $date->modify( 'first day next month' )->format( 'Y-m-d' ), "n"; ?> Explanation: 2010-01-31 15:48:21 2010-02-31 15:48:21 "next month" increases month number by 1 2010-03-03 15:48:21 February only has 28 days, so days are overflown into the next month 2010-03-04 15:48:21 "first day" adds one more day
  • 21. Relative Time "first day *of* next month" <?php $date = new DateTime( '2010-01-31 15:48:21' ); echo $date->modify( 'first day of next month' )->format( 'Y-m-d' ), "n"; ?> Explanation: 2010-01-31 15:48:21 2010-02-31 15:48:21 "next month" increases month number by 1 2010-02-01 15:48:21 "first day of" resets the day number to 1
  • 22. Relative Time "last day of third month" <?php $date = new DateTime( '2010-01-31 15:48:21' ); echo $date->modify( 'last day of third month' )->format( 'Y-m-d' ), "n"; ?> Explanation: 2010-01-31 15:48:21 2010-04-31 15:48:21 "third month" increases month number by 3 2010-05-00 15:48:21 "last day of" resets the day number to 0 and increases the month number by 1 2010-04-30 15:48:21 Day count is less than 1, so the algorithm corrects this to a proper date
  • 23. Periods (PHP 5.3) Initializing a period <?php // start, interval and count $db = new DateTime( '2008-07-31' ) ; $di = DateInterval::createFromDateString( 'next weekday' ); $p = new DatePeriod( $db, $di, 3 ); // start, interval and end $de = new DateTime ( '2008-08-05' ); $p = new DatePeriod( $db, $di, $de ); // ISO 8601 string $s = "2008-10-04T20:56:18Z/P0000-00-20T03:15:54/2008-12-22T00:00:00Z"; $p = new DatePeriod( $s ); ?>
  • 24. Periods (PHP 5.3) Iterating over a period <?php $db = new DateTime( '2008-12-31' ); $de = new DateTime( '2009-12-31' ); $di = DateInterval::createFromDateString( 'third tuesday of next month' ); $dp = new DatePeriod( $db, $di, $de, DatePeriod::EXCLUDE_START_DATE ); foreach ( $dp as $dt ) { echo $dt->format( "F jSn" ); } ?>
  • 25. php|architect's guide to Date/Time handling
  • 26. Resources ¡ñ This presentation: http://derickrethans.nl/talks.html ¡ñ World timezones: http://www.worldtimezone.com/index24.php ¡ñ Geonames: http://www.geonames.org/ ¡ñ Questions?: derick@php.net
  • 27. Thanks! Derick Rethans - derick@php.net - twitter: @derickr http://derickrethans.nl/talks.html http://joind.in/2232