Date manipulation

From Rosetta Code
Task
Date manipulation
You are encouraged to solve this task according to the task description, using any language you may know.
Task

Given the date string "March 7 2009 7:30pm EST",
output the time 12 hours later in any human-readable format.

As extra credit, display the resulting time in a time zone different from your own.

Ada[edit]

The Ada way: long, type-based, clear, reliable. Most of the code consists of declarations. Only standard libraries are required.

with Ada.Calendar;
with Ada.Calendar.Formatting;
with Ada.Calendar.Time_Zones;
with Ada.Integer_Text_IO;
with Ada.Text_IO;
 
procedure Date_Manipulation is
 
type Month_Name_T is
(January, February, March, April, May, June,
July, August, September, October, November, December);
 
type Time_Zone_Name_T is (EST, Lisbon);
 
type Period_T is (AM, PM);
 
package TZ renames Ada.Calendar.Time_Zones;
use type TZ.Time_Offset;
 
Time_Zone_Offset : array (Time_Zone_Name_T) of TZ.Time_Offset :=
(EST => -5 * 60,
Lisbon => 0);
 
Period_Offset : array (Period_T) of Natural :=
(AM => 0,
PM => 12);
 
package Month_Name_IO is
new Ada.Text_IO.Enumeration_IO (Month_Name_T);
 
package Time_Zone_Name_IO is
new Ada.Text_IO.Enumeration_IO (Time_Zone_Name_T);
 
package Period_IO is
new Ada.Text_IO.Enumeration_IO (Period_T);
 
package Std renames Ada.Calendar;
use type Std.Time;
 
package Fmt renames Std.Formatting;
 
function To_Number (Name : Month_Name_T) return Std.Month_Number is
begin
return Std.Month_Number (Month_Name_T'Pos (Name) + 1);
end;
 
function To_Time (S : String) return Std.Time is
Month : Month_Name_T;
Day : Std.Day_Number;
Year : Std.Year_Number;
Hour : Fmt.Hour_Number;
Minute : Fmt.Minute_Number;
Period : Period_T;
Time_Zone : Time_Zone_Name_T;
I : Natural;
begin
Month_Name_IO.Get
(From => S, Item => Month, Last => I);
Ada.Integer_Text_IO.Get
(From => S (I + 1 .. S'Last), Item => Day, Last => I);
Ada.Integer_Text_IO.Get
(From => S (I + 1 .. S'Last), Item => Year, Last => I);
Ada.Integer_Text_IO.Get
(From => S (I + 1 .. S'Last), Item => Hour, Last => I);
Ada.Integer_Text_IO.Get
(From => S (I + 2 .. S'Last), Item => Minute, Last => I);
-- here we start 2 chars down to skip the ':'
Period_IO.Get
(From => S (I + 1 .. S'Last), Item => Period, Last => I);
Time_Zone_Name_IO.Get
(From => S (I + 1 .. S'Last), Item => Time_Zone, Last => I);
return Fmt.Time_Of
(Year => Year,
Month => To_Number (Month),
Day => Day,
Hour => Hour + Period_Offset (Period),
Minute => Minute,
Second => 0,
Time_Zone => Time_Zone_Offset (Time_Zone));
end;
 
function Img
(Date : Std.Time; Zone : Time_Zone_Name_T) return String is
begin
return
Fmt.Image (Date => Date, Time_Zone => Time_Zone_Offset (Zone)) &
" " & Time_Zone_Name_T'Image (Zone);
end;
 
T1, T2 : Std.Time;
use Ada.Text_IO;
begin
T1 := To_Time ("March 7 2009 7:30pm EST");
T2 := T1 + 12.0 * 60.0 * 60.0;
Put_Line ("T1 => " & Img (T1, EST) & " = " & Img (T1, Lisbon));
Put_Line ("T2 => " & Img (T2, EST) & " = " & Img (T2, Lisbon));
end;

Result:

T1 => 2009-03-07 19:30:00 EST = 2009-03-08 00:30:00 LISBON
T2 => 2009-03-08 07:30:00 EST = 2009-03-08 12:30:00 LISBON

AppleScript[edit]

AppleScript has a built-in date class and can coerce a string to a date automatically. It also has reserved constants such as hours which are defined in the unit of seconds. There is no built-in support for time zones.

set x to "March 7 2009 7:30pm EST"
return (date x) + 12 * hours

Result is:

date "Sunday, March 8, 2009 7:30:00 AM"

AutoHotkey[edit]

DateString := "March 7 2009 7:30pm EST"
 
; split the given string with RegExMatch
Needle := "^(?P<mm>\S*) (?P<d>\S*) (?P<y>\S*) (?P<t>\S*) (?P<tz>\S*)$"
RegExMatch(DateString, Needle, $)
 
; split the time with RegExMatch
Needle := "^(?P<h>\d+):(?P<min>\d+)(?P<xm>[amp]+)$"
RegExMatch($t, Needle, $)
 
; convert am/pm to 24h format
$h += ($xm = "am") ? 0 : 12
 
; knitting YYYYMMDDHH24MI format
_YYYY := $y
_MM := Get_MonthNr($mm)
_DD := SubStr("00" $d, -1) ; last 2 chars
_HH24 := SubStr("00" $h, -1) ; last 2 chars
_MI := $min
YYYYMMDDHH24MI := _YYYY _MM _DD _HH24 _MI
 
; add 12 hours as requested
EnvAdd, YYYYMMDDHH24MI, 12, Hours
FormatTime, HumanReadable, %YYYYMMDDHH24MI%, d/MMM/yyyy HH:mm
 
; add 5 hours to convert to different timezone (GMT)
EnvAdd, YYYYMMDDHH24MI, 5, Hours
FormatTime, HumanReadable_GMT, %YYYYMMDDHH24MI%, d/MMM/yyyy HH:mm
 
; output
MsgBox, % "Given: " DateString "`n`n"
. "12 hours later:`n"
. "(" $tz "):`t" HumanReadable "h`n"
. "(GMT):`t" HumanReadable_GMT "h`n"
 
 
;---------------------------------------------------------------------------
Get_MonthNr(Month) { ; convert named month to 2-digit number
;---------------------------------------------------------------------------
If (Month = "January")
Result := "01"
Else If (Month = "February")
Result := "02"
Else If (Month = "March")
Result := "03"
Else If (Month = "April")
Result := "04"
Else If (Month = "May")
Result := "05"
Else If (Month = "June")
Result := "06"
Else If (Month = "July")
Result := "07"
Else If (Month = "August")
Result := "08"
Else If (Month = "September")
Result := "09"
Else If (Month = "October")
Result := "10"
Else If (Month = "November")
Result := "11"
Else If (Month = "December")
Result := "12"
Return, Result
}
Message box shows:
Given: March 7 2009 7:30pm EST

12 hours later:
(EST):	8/Mar/2009  07:30h
(GMT):	8/Mar/2009  12:30h

AWK[edit]

 
# syntax: GAWK -f DATE_MANIPULATION.AWK
BEGIN {
fmt = "%a %Y-%m-%d %H:%M:%S %Z" # DAY YYYY-MM-DD HH:MM:SS TZ
split("March 7 2009 7:30pm EST",arr," ")
M = (index("JanFebMarAprMayJunJulAugSepOctNovDec",substr(arr[1],1,3)) + 2) / 3
D = arr[2]
Y = arr[3]
hhmm = arr[4]
hh = substr(hhmm,1,index(hhmm,":")-1) + 0
mm = substr(hhmm,index(hhmm,":")+1,2) + 0
if (hh == 12 && hhmm ~ /am/) { hh = 0 }
else if (hh < 12 && hhmm ~ /pm/) { hh += 12 }
time = mktime(sprintf("%d %d %d %d %d %d",Y,M,D,hh,mm,0))
printf("time:  %s\n",strftime(fmt,time))
time += 12*60*60
printf("+12 hrs: %s\n",strftime(fmt,time))
exit(0)
}
 
Output:
time:    Sat 2009-03-07 19:30:00 Eastern Standard Time
+12 hrs: Sun 2009-03-08 08:30:00 Eastern Daylight Time

BBC BASIC[edit]

      INSTALL @lib$+"DATELIB"
 
date$ = "March 7 2009 7:30pm EST"
 
mjd% = FN_readdate(date$, "mdy", 0)
colon% = INSTR(date$, ":")
hours% = VAL(MID$(date$, colon%-2))
IF INSTR(date$, "am") IF hours%=12 hours% -= 12
IF INSTR(date$, "pm") IF hours%<>12 hours% += 12
mins% = VAL(MID$(date$, colon%+1))
 
now% = mjd% * 1440 + hours% * 60 + mins%
new% = now% + 12 * 60 : REM 12 hours later
 
PRINT FNformat(new%, "EST")
PRINT FNformat(new% + 5 * 60, "GMT")
PRINT FNformat(new% - 3 * 60, "PST")
END
 
DEF FNformat(datetime%, zone$)
LOCAL mjd%, hours%, mins%, ampm$
mjd% = datetime% DIV 1440
hours% = (datetime% DIV 60) MOD 24
mins% = datetime% MOD 60
 
IF hours% < 12 THEN ampm$ = "am" ELSE ampm$ = "pm"
IF hours% = 0 hours% += 12
IF hours% > 12 hours% -= 12
 
= FN_date$(mjd%, "MMMM d yyyy") + " " + STR$(hours%) + \
\ ":" + RIGHT$("0"+STR$(mins%), 2) + ampm$ + " " + zone$
ENDPROC
 
Output:
March 8 2009 7:30am EST
March 8 2009 12:30pm GMT
March 8 2009 4:30am PST

C[edit]

Works with: POSIX
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
 
int main()
{
struct tm ts;
time_t t;
const char *d = "March 7 2009 7:30pm EST";
 
strptime(d, "%B %d %Y %I:%M%p %Z", &ts);
/* ts.tm_hour += 12; instead of t += 12*60*60
works too. */

t = mktime(&ts);
t += 12*60*60;
printf("%s", ctime(&t));
 
return EXIT_SUCCESS;
}

Note: ctime treats the date as local, so that it is like the timezone information were discarded (to see the passage to daylight saving time I must change the date into March 28... no matter the timezone specified)

C#[edit]

class Program
{
static void Main(string[] args)
{
CultureInfo ci=CultureInfo.CreateSpecificCulture("en-US");
string dateString = "March 7 2009 7:30pm EST";
string format = "MMMM d yyyy h:mmtt z";
DateTime myDateTime = DateTime.ParseExact(dateString.Replace("EST","+6"),format,ci) ;
DateTime newDateTime = myDateTime.AddHours(12).AddDays(1) ;
Console.WriteLine(newDateTime.ToString(format).Replace("-5","EST")); //probably not the best way to do this
 
Console.ReadLine();
}
}

C++[edit]

Library: Boost

compiled with g++ -lboost_date_time

#include <string>
#include <iostream>
#include <boost/date_time/local_time/local_time.hpp>
#include <sstream>
#include <boost/date_time/gregorian/gregorian.hpp>
#include <vector>
#include <boost/algorithm/string.hpp>
#include <cstdlib>
#include <locale>
 
 
int main( ) {
std::string datestring ("March 7 2009 7:30pm EST" ) ;
//we must first parse the date string into a date , a time and a time
//zone part , to take account of present restrictions in the input facets
//of the Boost::DateTime library used for this example
std::vector<std::string> elements ;
//parsing the date string
boost::split( elements , datestring , boost::is_any_of( " " ) ) ;
std::string datepart = elements[ 0 ] + " " + "0" + elements[ 1 ] + " " +
elements[ 2 ] ; //we must add 0 to avoid trouble with the boost::date_input format strings
std::string timepart = elements[ 3 ] ;
std::string timezone = elements[ 4 ] ;
const char meridians[ ] = { 'a' , 'p' } ;
//we have to find out if the time is am or pm, to change the hours appropriately
std::string::size_type found = timepart.find_first_of( meridians, 0 ) ;
std::string twelve_hour ( timepart.substr( found , 1 ) ) ;
timepart = timepart.substr( 0 , found ) ; //we chop off am or pm
elements.clear( ) ;
boost::split( elements , timepart , boost::is_any_of ( ":" ) ) ;
long hour = std::atol( (elements.begin( ))->c_str( ) ) ;// hours in the string
if ( twelve_hour == "p" ) //it's post meridian, we're converting to 24-hour-clock
hour += 12 ;
long minute = std::atol( ( elements.begin( ) + 1)->c_str( ) ) ;
boost::local_time::tz_database tz_db ;
tz_db.load_from_file( "/home/ulrich/internetpages/date_time_zonespec.csv" ) ;
//according to the time zone database, this corresponds to one possible EST time zone
boost::local_time::time_zone_ptr dyc = tz_db.time_zone_from_region( "America/New_York" ) ;
//this is the string input format to initialize the date field
boost::gregorian::date_input_facet *f =
new boost::gregorian::date_input_facet( "%B %d %Y" ) ;
std::stringstream ss ;
ss << datepart ;
ss.imbue( std::locale( std::locale::classic( ) , f ) ) ;
boost::gregorian::date d ;
ss >> d ;
boost::posix_time::time_duration td ( hour , minute , 0 ) ;
//that's how we initialize the New York local time , by using date and adding
//time duration with values coming from parsed date input string
boost::local_time::local_date_time lt ( d , td , dyc ,
boost::local_time::local_date_time::NOT_DATE_TIME_ON_ERROR ) ;
std::cout << "local time: " << lt << '\n' ;
ss.str( "" ) ;
ss << lt ;
//we have to add 12 hours, so a new time duration object is created
boost::posix_time::time_duration td2 (12 , 0 , 0 , 0 ) ;
boost::local_time::local_date_time ltlater = lt + td2 ; //local time 12 hours later
boost::gregorian::date_facet *f2 =
new boost::gregorian::date_facet( "%B %d %Y , %R %Z" ) ;
std::cout.imbue( std::locale( std::locale::classic( ) , f2 ) ) ;
std::cout << "12 hours after " << ss.str( ) << " it is " << ltlater << " !\n" ;
//what's New York time in the Berlin time zone ?
boost::local_time::time_zone_ptr bt = tz_db.time_zone_from_region( "Europe/Berlin" ) ;
std::cout.imbue( std::locale( "de_DE.UTF-8" ) ) ; //choose the output forman appropriate for the time zone
std::cout << "This corresponds to " << ltlater.local_time_in( bt ) << " in Berlin!\n" ;
return 0 ;
}
 
Output:
local time: 2009-Mar-07 19:30:00 EST
12 hours after 2009-Mar-07 19:30:00 EST it is 2009-Mar-08 08:30:00 EDT !
This corresponds to 2009-Mär-08 13:30:00 CET in Berlin!

Clojure[edit]

(import java.util.Date
java.text.SimpleDateFormat)
 
(defn time+12 [s]
(let [sdf (SimpleDateFormat. "MMMM d yyyy h:mma zzz")]
(-> (.parse sdf s)
(.getTime ,)
(+ , 43200000)
long
(Date. ,)
(->> , (.format sdf ,)))))

COBOL[edit]

Tested with GnuCOBOL

Two parts to this example. Following the task spec using POSIX routines, and a more standardized COBOL form. COBOL 2014 uses ISO8601 date and time formats, and these formats may be more common in COBOL applications.

       identification division.
program-id. date-manipulation.
 
environment division.
configuration section.
repository.
function all intrinsic.
 
data division.
working-storage section.
01 given-date.
05 filler value z"March 7 2009 7:30pm EST".
01 date-spec.
05 filler value z"%B %d %Y %I:%M%p %Z".
 
01 time-struct.
05 tm-sec usage binary-long.
05 tm-min usage binary-long.
05 tm-hour usage binary-long.
05 tm-mday usage binary-long.
05 tm-mon usage binary-long.
05 tm-year usage binary-long.
05 tm-wday usage binary-long.
05 tm-yday usage binary-long.
05 tm-isdst usage binary-long.
05 tm-gmtoff usage binary-c-long.
05 tm-zone usage pointer.
01 scan-index usage pointer.
 
01 time-t usage binary-c-long.
01 time-tm usage pointer.
 
01 reform-buffer pic x(64).
01 reform-length usage binary-long.
 
01 current-locale usage pointer.
 
01 iso-spec constant as "YYYY-MM-DDThh:mm:ss+hh:mm".
01 iso-date constant as "2009-03-07T19:30:00-05:00".
01 date-integer pic 9(9).
01 time-integer pic 9(9).
 
procedure division.
 
call "strptime" using
by reference given-date
by reference date-spec
by reference time-struct
returning scan-index
on exception
display "error calling strptime" upon syserr
end-call
display "Given: " given-date
 
if scan-index not equal null then
*> add 12 hours, and reform as local
call "mktime" using time-struct returning time-t
add 43200 to time-t
perform form-datetime
 
*> reformat as Pacific time
set environment "TZ" to "PST8PDT"
call "tzset" returning omitted
perform form-datetime
 
*> reformat as Greenwich mean
set environment "TZ" to "GMT"
call "tzset" returning omitted
perform form-datetime
 
 
*> reformat for Tokyo time, as seen in Hong Kong
set environment "TZ" to "Japan"
call "tzset" returning omitted
call "setlocale" using by value 6 by content z"en_HK.utf8"
returning current-locale
on exception
display "error with setlocale" upon syserr
end-call
move z"%c" to date-spec
perform form-datetime
else
display "date parse error" upon syserr
end-if
 
*> A more standard COBOL approach, based on ISO8601
display "Given: " iso-date
move integer-of-formatted-date(iso-spec, iso-date)
to date-integer
 
move seconds-from-formatted-time(iso-spec, iso-date)
to time-integer
 
add 43200 to time-integer
if time-integer greater than 86400 then
subtract 86400 from time-integer
add 1 to date-integer
end-if
display " " substitute(formatted-datetime(iso-spec
date-integer, time-integer, -300), "T", "/")
 
goback.
 
form-datetime.
call "localtime" using time-t returning time-tm
call "strftime" using
by reference reform-buffer
by value length(reform-buffer)
by reference date-spec
by value time-tm
returning reform-length
on exception
display "error calling strftime" upon syserr
end-call
if reform-length > 0 and <= length(reform-buffer) then
display " " reform-buffer(1 : reform-length)
else
display "date format error" upon syserr
end-if
.
end program date-manipulation.
 
Output:
prompt$ cobc -xj date-manipulation.cob
Given: March 7 2009 7:30pm EST
       March 08 2009 08:30AM EDT
       March 08 2009 05:30AM PDT
       March 08 2009 12:30PM GMT
       Sunday, March 08, 2009 PM09:30:00 JST
Given: 2009-03-07T19:30:00-05:00
       2009-03-08/07:30:00-05:00

Delphi[edit]

 
program DateManipulation;
 
{$APPTYPE CONSOLE}
 
uses
SysUtils,
DateUtils;
 
function MonthNumber(aMonth: string): Word;
begin
//Convert a string value representing the month
//to its corresponding numerical value
if aMonth = 'January' then Result:= 1
else if aMonth = 'February' then Result:= 2
else if aMonth = 'March' then Result:= 3
else if aMonth = 'April' then Result:= 4
else if aMonth = 'May' then Result:= 5
else if aMonth = 'June' then Result:= 6
else if aMonth = 'July' then Result:= 7
else if aMonth = 'August' then Result:= 8
else if aMonth = 'September' then Result:= 9
else if aMonth = 'October' then Result:= 10
else if aMonth = 'November' then Result:= 11
else if aMonth = 'December' then Result:= 12
else Result:= 12;
end;
 
function ParseString(aDateTime: string): TDateTime;
var
strDay,
strMonth,
strYear,
strTime: string;
iDay,
iMonth,
iYear: Word;
TimePortion: TDateTime;
begin
//Decode the month from the given string
strMonth:= Copy(aDateTime, 1, Pos(' ', aDateTime) - 1);
Delete(aDateTime, 1, Pos(' ', aDateTime));
iMonth:= MonthNumber(strMonth);
 
//Decode the day from the given string
strDay:= Copy(aDateTime, 1, Pos(' ', aDateTime) - 1);
Delete(aDateTime, 1, Pos(' ', aDateTime));
iDay:= StrToIntDef(strDay, 30);
 
//Decode the year from the given string
strYear:= Copy(aDateTime, 1, Pos(' ', aDateTime) -1);
Delete(aDateTime, 1, Pos(' ', aDateTime));
iYear:= StrToIntDef(strYear, 1899);
 
//Decode the time value from the given string
strTime:= Copy(aDateTime, 1, Pos(' ', aDateTime) -1);
 
//Encode the date value and assign it to result
Result:= EncodeDate(iYear, iMonth, iDay);
 
//Encode the time value and add it to result
if TryStrToTime(strTime, TimePortion) then
Result:= Result + TimePortion;
end;
 
function Add12Hours(aDateTime: string): string;
var
tmpDateTime: TDateTime;
begin
//Adding 12 hours to the given
//date time string value
tmpDateTime:= ParseString(aDateTime);
tmpDateTime:= IncHour(tmpDateTime, 12);
 
//Formatting the output
Result:= FormatDateTime('mm/dd/yyyy hh:mm AM/PM', tmpDateTime);
end;
 
begin
Writeln(Add12Hours('March 7 2009 7:30pm EST'));
Readln;
end.
 
Output:
"03/08/2009 07:30 AM" 

EchoLisp[edit]

 
(define my-date (string->date "March 7 2009 7:30 pm EST"))
→ Sun Mar 08 2009 01:30:00 GMT+0100 (CET)
 
(date-add! my-date (* 12 3600))
→ Sun Mar 08 2009 13:30:00 GMT+0100 (CET)
(string->date my-date)
 
(date->string my-date)
"8/3/2009 13:30:00" ;; human localized, Paris time.
 

Erlang[edit]

It is human readable to me.

 
-module( date_manipulation ).
 
-export( [task/0] ).
 
task() ->
{Date_time, TZ} = date_time_tz_from_string( "March 7 2009 7:30pm EST" ),
Seconds1 = calendar:datetime_to_gregorian_seconds( Date_time ),
Seconds2 = calendar:datetime_to_gregorian_seconds( {calendar:gregorian_days_to_date(0), {12, 0, 0}} ),
Date_time_later = calendar:gregorian_seconds_to_datetime( Seconds1 + Seconds2 ),
{Date_time_later, TZ}.
 
 
 
date_time_tz_from_string( String ) ->
[Month, Date, Year, Time, TZ] = string:tokens( String, " " ),
[Hour, Minute] = string:tokens( Time, ":" ),
{{date_from_strings(Year, Month, Date), time_from_strings(Hour, Minute)}, TZ}.
 
date_from_strings( Year, Month, Date ) ->
{erlang:list_to_integer(Year), date_from_strings_month(Month), erlang:list_to_integer(Date)}.
 
date_from_strings_month( "January" ) -> 1;
date_from_strings_month( "February" ) -> 2;
date_from_strings_month( "March" ) -> 3;
date_from_strings_month( "April" ) -> 4;
date_from_strings_month( "May" ) -> 5;
date_from_strings_month( "June" ) -> 6;
date_from_strings_month( "July" ) -> 7;
date_from_strings_month( "August" ) -> 8;
date_from_strings_month( "September" ) -> 9;
date_from_strings_month( "October" ) -> 10;
date_from_strings_month( "November" ) -> 11;
date_from_strings_month( "December" ) -> 12.
 
time_from_strings( Hour, Minute_12hours ) ->
{ok, [Minute], AM_PM} = io_lib:fread("~d", Minute_12hours ),
{time_from_strings_hour( Hour, string:to_lower(AM_PM) ), Minute, 0}.
 
time_from_strings_hour( Hour, "am" ) -> erlang:list_to_integer( Hour );
time_from_strings_hour( Hour, "pm" ) -> erlang:list_to_integer( Hour ) + 12.
 
Output:
24> date_manipulation:task().
{{{2009,3,8},{7,30,0}},"EST"}

Euphoria[edit]

 
--Date Manipulation task from Rosetta Code wiki
--User:Lnettnay
 
include std/datetime.e
 
datetime dt
 
dt = new(2009, 3, 7, 19, 30)
dt = add(dt, 12, HOURS)
printf(1, "%s EST\n", {format(dt, "%B %d %Y %I:%M %p")})
 
Output:
March 08 2009 07:30 AM EST

F#[edit]

The .NET framework does not support parsing of time zone identifiers like "EST". We have to use time zone offsets like "-5".

open System
 
let main() =
let est = TimeZoneInfo.FindSystemTimeZoneById("Eastern Standard Time")
let date = DateTime.Parse("March 7 2009 7:30pm -5" )
let date_est = TimeZoneInfo.ConvertTime( date, est)
let date2 = date.AddHours(12.0)
let date2_est = TimeZoneInfo.ConvertTime( date2, est)
Console.WriteLine( "Original date in local time : {0}", date )
Console.WriteLine( "Original date in EST  : {0}", date_est )
Console.WriteLine( "12 hours later in local time: {0}", date2 )
Console.WriteLine( "12 hours later in EST  : {0}", date2_est )
 
main()
Output:
(depends on locale settings):
Original date in local time : 08.03.2009 01:30:00
Original date in EST        : 07.03.2009 19:30:00
12 hours later in local time: 08.03.2009 13:30:00
12 hours later in EST       : 08.03.2009 07:30:00

Fantom[edit]

In the expression "d + 12hr", the "12hr" defines an instance of the Duration class, interpreting the duration in nanoseconds.

 
fansh> d := DateTime.fromLocale("March 7 2009 7:30pm EST", "MMMM D YYYY h:mmaa zzz")
fansh> d
2009-03-07T19:30:00-05:00 EST
fansh> d + 12hr
2009-03-08T07:30:00-05:00 EST
fansh> (d+12hr).toTimeZone(TimeZone("London")) // the extra credit!
2009-03-08T12:30:00Z London
 

Frink[edit]

Frink parses a large number of date/time formats, has robust date/time math, and automatically converts between timezones. By default, output times are in the user's defined timezone.

 
### MMM dd yyyy h:mma ###
d = parseDate["March 7 2009 7:30pm EST"]
println[d + 12 hours -> Eastern]
println[d + 12 hours -> Switzerland] // Extra credit
 
Output:
AD 2009-03-08 AM 08:30:00.000 (Sun) Eastern Daylight Time
AD 2009-03-08 PM 01:30:00.000 (Sun) Central European Time

FunL[edit]

import time.{TimeZone, Date, SimpleDateFormat, Hour}
 
pattern = SimpleDateFormat( 'MMMM d yyyy h:mma zzz' )
date = pattern.parse( 'March 7 2009 7:30pm EST' )
later = Date( date.getTime() + 12 Hour )
println( pattern.format(later) ) // Eastern Daylight Time
pattern.setTimeZone( TimeZone.getTimeZone('America/Los_Angeles') )
println( pattern.format(later) ) // U.S. Pacific Time
Output:
March 8 2009 8:30AM EDT
March 8 2009 5:30AM PDT

Go[edit]

package main
 
import (
"fmt"
"time"
)
 
const taskDate = "March 7 2009 7:30pm EST"
const taskFormat = "January 2 2006 3:04pm MST"
 
func main() {
if etz, err := time.LoadLocation("US/Eastern"); err == nil {
time.Local = etz
}
fmt.Println("Input: ", taskDate)
t, err := time.Parse(taskFormat, taskDate)
if err != nil {
fmt.Println(err)
return
}
t = t.Add(12 * time.Hour)
fmt.Println("+12 hrs: ", t)
if _, offset := t.Zone(); offset == 0 {
fmt.Println("No time zone info.")
return
}
atz, err := time.LoadLocation("US/Arizona")
if err == nil {
fmt.Println("+12 hrs in Arizona:", t.In(atz))
}
}
Output:
Input:              March 7 2009 7:30pm EST
+12 hrs:            2009-03-08 08:30:00 -0400 EDT
+12 hrs in Arizona: 2009-03-08 05:30:00 -0700 MST

Groovy[edit]

Solution:

Library: Joda Time version 2.1
import org.joda.time.*
import java.text.*
 
def dateString = 'March 7 2009 7:30pm EST'
 
def sdf = new SimpleDateFormat('MMMM d yyyy h:mma zzz')
 
DateTime dt = new DateTime(sdf.parse(dateString))
 
println (dt)
println (dt.plusHours(12))
println (dt.plusHours(12).withZone(DateTimeZone.UTC))
Output:
2009-03-07T18:30:00.000-06:00
2009-03-08T07:30:00.000-05:00
2009-03-08T12:30:00.000Z

Haskell[edit]

import Data.Time.Clock.POSIX
import Data.Time.Format
import System.Locale
 
main = print t2
where t1 = readTime defaultTimeLocale
"%B %e %Y %l:%M%P %Z"
"March 7 2009 7:30pm EST"
t2 = posixSecondsToUTCTime $ 12*60*60 + utcTimeToPOSIXSeconds t1

HicEst[edit]

 
CHARACTER date="March 7 2009 7:30pm EST", am_pm, result*20
 
EDIT(Text=date, Parse=cMonth, GetPosition=next)
month = 1 + EDIT(Text='January,February,March,April,May,June,July,August,September,October,November,December', Right=cMonth, Count=',' )
READ(Text=date(next:)) day, year, hour, minute, am_pm
hour = hour + 12*(am_pm == 'p')
TIME(MOnth=month, Day=day, Year=year, Hour=hour, MInute=minute, TO, Excel=xls_day)
WRITE(Text=result, Format="UWWW CCYY-MM-DD HH:mm") xls_day + 0.5
! result = "Sun 2009-03-08 07:30"
END
 

Icon and Unicon[edit]

This uses the datetime procedures from the Icon Programming Library. Several supplemental procedures were needed to normalize the date format (as the one used in the task isn't fully compatible with the library), and to better handle time zones (as the library routines don't handle part hour time zones).

link datetime
 
procedure main()
write("input = ",s := "March 7 2009 7:30pm EST" )
write("+12 hours = ",SecToTZDateLine(s := TZDateLineToSec(s) + 12*3600,"EST"))
write(" = ",SecToTZDateLine(s,"UTC"))
write(" = ",SecToTZDateLine(s,"NST"))
end
 
procedure SecToTZDateLine(s,tz) #: returns dateline + time zone given seconds
return NormalizedDate(SecToDateLine(s+\(_TZdata("table")[\tz|"UTC"]))||" "|| tz)
end
 
procedure TZDateLineToSec(s) #: returns seconds given dateline (and time zone)
return (
NormalizedDate(s) ? (
d := tab(find("am"|"pm")+2),tab(many('\t ,')),
tz := \_TZdata("table")[tab(0)]
),
DateLineToSec(d) - tz)
end
 
procedure NormalizedDate(s) #: returns a consistent dateline
static D,M
initial {
D := ["Saturday","Sunday","Monday","Tuesday","Wednesday","Thursday","Friday"]
M := ["January","February","March","April","May","June",
"July","August","September","October","November","December"]
}
 
map(s) ? { # parse and build consistent dateline
ds := 1(x := !D, =map(x)) | "" # Weekday
ds ||:= 1(", ", tab(many('\t ,')|&pos))
ds ||:= 1(x := !M, =map(x)) | fail # Month
ds ||:= 1(" ", tab(many('\t ,')|&pos))
ds ||:= tab(many(&digits)) | fail # day
ds ||:= 1(", ", tab(many('\t ,'))) | fail
ds ||:= tab(many(&digits)) | fail # year
ds ||:= 1(" ", tab(many('\t ,'))) | fail
ds ||:= tab(many(&digits))||(=":"||tab(many(&digits))|&null) | fail # time
ds ||:= 1(" ", tab(many('\t ,')|&pos))
ds ||:= =("am"|"pm") | fail # halfday
ds ||:= 1(" ", tab(many('\t ,')|&pos))
tz := map(=!_TZdata("list"),&lcase,&ucase)
}
 
if ds[1] == "," then
ds := SecToDateLine(DateLineToSec("Sunday"||ds)) # get IPL to fix weekday
 
return ds ||:= " " || \tz|"UTC"
end
 
procedure _TZdata(x) #: internal return TZ data (demo version incomplete)
static TZ,AZ
initial {
TZ := table()
AZ := []
"UTC/0;ACDT/+10.5;CET/1;EST/-5;NPT/+5.75;NST/-3.5;PST/-8;" ?
while ( a := tab(find("/")), move(1), o := tab(find(";")), move(1) ) do {
TZ[map(a)] := TZ[a] := integer(3600*o)
put(AZ,a,map(a))
}
every TZ[&null|""] := TZ["UTC"]
}
return case x of { "list" : AZ ; "table" : TZ }
end

datetime provides SecToDateLine, and DateLineToSec these convert between Icon's &dateline format and seconds from a configurable base date (which defaults to the normal 1970 epoch).

Output:
input      = March 7 2009 7:30pm EST
+12 hours  = Sunday, March 8, 2009 7:30 am  EST
           = Sunday, March 8, 2009 12:30 pm  UTC
           = Sunday, March 8, 2009 9:00 am  NST

J[edit]

A natural mechanism for representing dates in J is what J's documentation refers to as a "timestamp" -- a list of six numbers in ISO 8601 order (year, month, date, hour, minute, second). An alternate representation uses a single number specifying the number of milliseconds since January 1, 1800.

With that in mind:

require'dates'
months=: <;._2 tolower 0 :0
January
February
March
April
May
June
July
August
September
October
November
December
)
 
numbers=: _".' '"_`(1 I.@:-e.&(":i.10)@])`]}~
words=: [:;:@tolower' '"_`(I.@(tolower = toupper)@])`]}~
getyear=: >.[email protected]
getmonth=: 1 + months <.[email protected] words
getday=: {.@(numbers -. getyear)
gethour=: (2 { numbers) + 12 * (<'pm') e. words
getminsec=: 2 {. 3}. numbers
 
getts=: getyear, getmonth, getday, gethour, getminsec
timeadd=: 1&tsrep@+&tsrep
deltaT=: (1 tsrep 0)&([ + -@#@[ {. ])

This parser assumes that numeric date information appears to the left of time information, that month name is spelled out in full and that time zone may be ignored. (Alternate date representations are straightforward to implement but turn this into a somewhat open-ended problem).

Note that J's tsrep library routine converts from timestamp to milliseconds and 1 tsrep coverts from milliseconds to timestamp.

Example use:

   (deltaT 12 0 0) timeadd getts 'March 7 2009 7:30pm EST'
2009 3 8 7 30 0
timestamp (deltaT 12 0 0) timeadd getts 'March 7 2009 7:30pm EST'
08 Mar 2009 07:30:00
isotimestamp (deltaT 12 0 0) timeadd getts 'March 7 2009 7:30pm EST'
2009-03-08 07:30:00.000

Note that the isotimestamp representation uses a space instead of a 'T' to separate date and time.

Java[edit]

import java.util.Date;
import java.text.SimpleDateFormat;
public class DateManip{
public static void main(String[] args) throws Exception{
String dateStr = "March 7 2009 7:30pm EST";
 
SimpleDateFormat sdf = new SimpleDateFormat("MMMM d yyyy h:mma zzz");
 
Date date = sdf.parse(dateStr);
 
date.setTime(date.getTime() + 43200000l);
 
System.out.println(sdf.format(date));
}
 
}
Output:
March 8 2009 8:30AM EDT

or using System.out.println(date); as the last line:

Sun Mar 08 08:30:00 EDT 2009

JavaScript[edit]

Input: March 7 2009 7:30pm EST

The input string is ambiguous since EST might represent any one of 3 different world time zones. Will assume US Eastern Standard Time of UTC -5 hours.

Javascript date objects are always in the local time zone. If a date and time is provided in a different time zone, it must be dealt with manually as the date object's time zone offset is read only. Consequently, there may be issues if daylight saving is observed in one location but not the other.

While ECMA-262 Ed 5 specifies a Date.parse method, it is not widely supported (2011) and parsing of strings other than the format specified are implementation dependent. Since the test string doesn't conform to the standard, it must be manually parsed.

function add12hours(dateString) {
 
// Get the parts of the date string
var parts = dateString.split(/\s+/),
date = parts[1],
month = parts[0],
year = parts[2],
time = parts[3];
 
var hr = Number(time.split(':')[0]),
min = Number(time.split(':')[1].replace(/\D/g,'')),
ampm = time && time.match(/[a-z]+$/i)[0],
zone = parts[4].toUpperCase();
 
var months = ['January','February','March','April','May','June',
'July','August','September','October','November','December'];
var zones = {'EST': 300, 'AEST': -600}; // Minutes to add to zone time to get UTC
 
// Convert month name to number, zero indexed. Return if invalid month
month = months.indexOf(month);
if (month === -1) { return; }
 
// Add 12 hours as specified. Add another 12 if pm for 24hr time
hr += (ampm.toLowerCase() === 'pm') ? 24 : 12
 
// Create a date object in local zone
var localTime = new Date(year, month, date);
localTime.setHours(hr, min, 0, 0);
 
// Adjust localTime minutes for the time zones so it is now a local date
// representing the same moment as the source date plus 12 hours
localTime.setMinutes(localTime.getMinutes() + zones[zone] - localTime.getTimezoneOffset() );
return localTime;
}
 
var inputDateString = 'March 7 2009 7:30pm EST';
 
console.log(
'Input: ' + inputDateString + '\n' +
'+12hrs in local time: ' + add12hours(inputDateString)
);

jq[edit]

Works with: jq version version with mktime
"March 7 2009 7:30pm EST"
| strptime("%B %d %Y %I:%M%p %Z")
| .[3] += 12
| mktime | strftime("%B %d %Y %I:%M%p %Z")
Output:
"March 08 2009 07:30AM EST"

Lasso[edit]

local(date) = date('March 7 2009 7:30PM EST',-format='MMMM d yyyy h:mma z')
#date->add(-hour = 24)
#date->timezone = 'GMT'
Output:
March 9 2009 12:30AM GMT

Lua[edit]

The following solution is quite ugly, but unfortunately there is not anything like 'strptime'-function in Lua.

 
str = string.lower( "March 7 2009 7:30pm EST" )
 
month = string.match( str, "%a+" )
if month == "january" then month = 1
elseif month == "february" then month = 2
elseif month == "march" then month = 3
elseif month == "april" then month = 4
elseif month == "may" then month = 5
elseif month == "june" then month = 6
elseif month == "july" then month = 7
elseif month == "august" then month = 8
elseif month == "september" then month = 9
elseif month == "october" then month = 10
elseif month == "november" then month = 11
elseif month == "december" then month = 12
end
 
strproc = string.gmatch( str, "%d+" )
day = strproc()
year = strproc()
hour = strproc()
min = strproc()
 
if string.find( str, "pm" ) then hour = hour + 12 end
 
print( os.date( "%c", os.time{ year=year, month=month, day=day, hour=hour, min=min, sec=0 } + 12 * 3600 ) )
 
Output:
Sun Mar  8 07:30:00 2009

Mathematica / Wolfram Language[edit]

dstr = "March 7 2009 7:30pm EST";
DateString[DatePlus[dstr, {12, "Hour"}], {"DayName", " ", "MonthName", " ", "Day", " ", "Year", " ", "Hour24", ":", "Minute", "AMPM"}]

mIRC Scripting Language[edit]

echo -ag $asctime($calc($ctime(March 7 2009 7:30pm EST)+43200))

NetRexx[edit]

/* NetRexx */
options replace format comments java crossref symbols binary
 
import java.text.SimpleDateFormat
import java.text.ParseException
 
runSample(arg)
return
 
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
method manipulateDate(sampleDate, dateFmt, dHours = 0) private static
formatter = SimpleDateFormat(dateFmt)
msHours = dHours * 60 * 60 * 1000 -- hours in milliseconds
day = formatter.parse(sampleDate)
day.setTime(day.getTime() + msHours)
formatted = formatter.format(day)
return formatted
 
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
method runSample(arg) private static
do
sampleDate = 'March 7 2009 7:30pm EST'
dateFmt = "MMMM d yyyy h:mma z"
say sampleDate
say manipulateDate(sampleDate, dateFmt, 12)
catch ex = Exception
ex.printStackTrace()
end
return
 
Output:
March 7 2009 7:30pm EST
March 8 2009 8:30AM EDT

Nim[edit]

import posix, times
 
var ts: Ttm
discard "March 7 2009 7:30pm EST".strptime("%B %d %Y %I:%M%p %Z", ts)
ts.tmHour += 12
echo ts.mktime
Output:
Sun Mar  8 07:30:00 2009

ooRexx[edit]

version 1[edit]

 
sampleDate = 'March 7 2009 7:30pm EST'
 
Parse var sampleDate month day year time zone
basedate = .DateTime~fromNormalDate(day month~left(3) year)
basetime = .DateTime~fromCivilTime(time)
-- this will give us this in a merged format...now we can add in the
-- timezone informat
mergedTime = (basedate + basetime~timeofday)~isoDate
zone = .TimeZoneDataBase~getTimeZone(zone)
 
finalTime = .DateTime~fromIsoDate(mergedTime, zone~datetimeOffset)
 
say 'Original date:' finalTime~utcIsoDate
say 'Result after adding 12 hours:' finalTime~addHours(12)~utcIsoDate
say 'Result shifted to UTC:' finalTime~toTimeZone(0)~utcIsoDate
say 'Result shifted to Pacific Standard Time:' finalTime~toTimeZone(.TimeZoneDataBase~getTimeZone('PST')~datetimeOffset)~utcIsoDate
say 'Result shifted to NepalTime Time:' finalTime~toTimeZone(.TimeZoneDataBase~getTimeZone('NPT')~datetimeOffset)~utcIsoDate
 
-- a descriptor for timezone information
::class timezone
::method init
expose code name offset altname region
use strict arg code, name, offset, altname, region
code~upper
 
::attribute code GET
::attribute name GET
::attribute offset GET
::attribute altname GET
::attribute region GET
::attribute datetimeOffset GET
expose offset
return offset * 60
 
-- our database of timezones
::class timezonedatabase
-- initialize the class object. This occurs when the program is first loaded
::method init class
expose timezones
 
timezones = .directory~new
-- extract the timezone data which is conveniently stored in a method
data = self~instanceMethod('TIMEZONEDATA')~source
 
loop line over data
-- skip over the comment delimiters, blank lines, and the 'return'
-- lines that force the comments to be included in the source
if line = '/*' | line = '*/' | line = '' | line = 'return' then iterate
parse var line '{' region '}'
if region \= '' then do
zregion = region
iterate
end
else do
parse var line abbrev . '!' fullname '!' altname . '!' offset .
timezone = .timezone~new(abbrev, fullname, offset, altname, zregion)
timezones[timezone~code] = timezone
end
end
 
::method getTimezone class
expose timezones
use strict arg code
return timezones[code~upper]
 
-- this is a dummy method containing the timezone database data.
-- we'll access the source directly and extract the data held in comments
-- the two return statements force the comment lines to be included in the
-- source rather than processed as part of comments between directives
::method timeZoneData class private
return
/*
{Universal}
UTC  ! Coordinated Universal Time  !  ! 0
 
{Europe}
BST  ! British Summer Time  !  ! +1
CEST ! Central European Summer Time  !  ! +2
CET  ! Central European Time  !  ! +1
EEST ! Eastern European Summer Time  !  ! +3
EET  ! Eastern European Time  !  ! +2
GMT  ! Greenwich Mean Time  !  ! 0
IST  ! Irish Standard Time  !  ! +1
KUYT ! Kuybyshev Time  !  ! +4
MSD  ! Moscow Daylight Time  !  ! +4
MSK  ! Moscow Standard Time  !  ! +3
SAMT ! Samara Time  !  ! +4
WEST ! Western European Summer Time  !  ! +1
WET  ! Western European Time  !  ! 0
 
{North America}
ADT  ! Atlantic Daylight Time  ! HAA  ! -3
AKDT ! Alaska Daylight Time  ! HAY  ! -8
AKST ! Alaska Standard Time  ! HNY  ! -9
AST  ! Atlantic Standard Time  ! HNA  ! -4
CDT  ! Central Daylight Time  ! HAC  ! -5
CST  ! Central Standard Time  ! HNC  ! -6
EDT  ! Eastern Daylight Time  ! HAE  ! -4
EGST ! Eastern Greenland Summer Time  !  ! 0
EGT  ! East Greenland Time  !  ! -1
EST  ! Eastern Standard Time  ! HNE,ET ! -5
HADT ! Hawaii-Aleutian Daylight Time  !  ! -9
HAST ! Hawaii-Aleutian Standard Time  !  ! -10
MDT  ! Mountain Daylight Time  ! HAR  ! -6
MST  ! Mountain Standard Time  ! HNR  ! -7
NDT  ! Newfoundland Daylight Time  ! HAT  ! -2.5
NST  ! Newfoundland Standard Time  ! HNT  ! -3.5
PDT  ! Pacific Daylight Time  ! HAP  ! -7
PMDT ! Pierre & Miquelon Daylight Time  !  ! -2
PMST ! Pierre & Miquelon Standard Time  !  ! -3
PST  ! Pacific Standard Time  ! HNP,PT ! -8
WGST ! Western Greenland Summer Time  !  ! -2
WGT  ! West Greenland Time  !  ! -3
 
{India and Indian Ocean}
IST  ! India Standard Time  !  ! +5.5
PKT  ! Pakistan Standard Time  !  ! +5
BST  ! Bangladesh Standard Time  !  ! +6 -- Note: collision with British Summer Time
NPT  ! Nepal Time  !  ! +5.75
BTT  ! Bhutan Time  !  ! +6
BIOT ! British Indian Ocean Territory Time ! IOT  ! +6
MVT  ! Maldives Time  !  ! +5
CCT  ! Cocos Islands Time  !  ! +6.5
TFT  ! French Southern and Antarctic Time  !  ! +5
*/

return
 

version 2[edit]

This example is written using the Open Object Rexx dialect to take advantage of the DateTime built–in class.

/* Rexx */
sampleDate = 'March 7 2009 7:30pm EST'
 
Parse value sampleDate with tm td ty tt tz .
Parse value time('l', tt, 'c') with hh ':' mm ':' ss '.' us .
 
timezones. = ''
Call initTimezones
mn = monthNameToNumber(tm)
zuluOffset = getTZOffset(tz)
 
Drop !TZ !MSG
day.1.!TZ = zuluOffset
day.1.!MSG = 'Original date:'
day.1 = .DateTime~new(ty, mn, td, hh, mm, ss, us, day.1.!TZ * 60)
day.2.!TZ = zuluOffset
day.2.!MSG = 'Result after adding 12 hours to date:'
day.2 = day.1~addHours(12)
day.3.!TZ = getTZOffset('UTC') -- AKA GMT == Greenwich Mean Time
day.3.!MSG = 'Result shifted to "UTC (Zulu)" time zone:'
day.3 = day.1~toTimeZone(day.3.!TZ)
day.4.!TZ = getTZOffset('PST') -- Pacific Standard Time
day.4.!MSG = 'Result shifted to "Pacific Standard Time" time zone:'
day.4 = day.2~toTimeZone(day.4.!TZ * 60)
day.5.!TZ = getTZOffset('NPT') -- Nepal Time
day.5.!MSG = 'Result shifted to "Nepal Time" time zone:'
day.5 = day.2~toTimeZone(day.5.!TZ * 60)
day.0 = 5
 
Say 'Manipulate the date string "'sampleDate'" and present results in ISO 8601 timestamp format:'
Say
Loop d_ = 1 to day.0
Say day.d_.!MSG
Say day.d_~isoDate || getUTCOffset(day.d_.!TZ, 'z')
Say
End d_
 
Return 0
 
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
isTrue: Procedure; Return (1 == 1)
 
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
isFalse: Procedure; Return \isTrue()
 
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
monthNameToNumber:
Procedure
Do
Parse arg tm .
 
mnamesList = 'January February March April May June July August September October November December'
 
Loop mn = 1 to mnamesList~words
mnx = mnamesList~word(mn)
If mnx~upper~abbrev(tm~upper, 3) then Do
Leave mn
End
End mn
 
Return mn
End
Exit
 
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
getTZOffset:
Procedure expose timezones.
Do
Parse upper arg tz .
Drop !REGION !FULLNAME !OFFSET !ZNAMEALT
 
offset = 0
Loop z_ = 1 to timezones.0
If tz = timezones.z_ then Do
offset = timezones.z_.!OFFSET
Leave z_
End
End z_
 
Return offset;
End
Exit
 
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
getUTCOffset:
Procedure expose timezones.
Do
Parse arg oh ., zulu .
 
oha = abs(oh)
If oha = 0 & 'ZULU'~abbrev(zulu~upper, 1) then Do
offset = 'Z'
End
else Do
If oh < 0 then ew = '-'
else ew = '+'
om = oha * 60
oom = om // 60 % 1
ooh = om % 60
offset = ew || ooh~right(2, 0) || oom~right(2, 0)
End
 
Return offset
End
Exit
 
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
initTimezones:
Procedure expose timezones.
Do
-- Read time zone info from formatted comment block below
Drop !REGION !FULLNAME !OFFSET !ZNAMEALT
timezones.0 = 0
region = ''
 !datBegin = '__DATA__'
 !datEnd = '__ENDD__'
 !reading = isFalse()
 
Loop l_ = 1 to sourceline()
Parse value sourceline(l_) with sl 0 hd +8 .
If !reading then Do
If hd = !datEnd then Do
 !reading = isFalse()
Leave l_
End
else Do
Parse value sl with sl '--' .
If sl~strip~length = 0 then Iterate l_
Parse value sl with,
0 '{' zRegion '}',
0 zAbbrev . '!' zFullName '!' zAbbrevOther . '!' zUOffset .
If zRegion~length \= 0 then Do
region = zRegion
Iterate l_
End
else Do
z_ = timezones.0 + 1
timezones.0 = z_
timezones.z_ = zAbbrev~strip~upper
timezones.z_.!FULLNAME = zFullName~strip
timezones.z_.!OFFSET = zUOffset~format
timezones.z_.!ZNAMEALT = zAbbrevOther~strip~upper
timezones.z_.!REGION = region
End
End
End
else Do
If hd = !datBegin then Do
 !reading = isTrue()
End
Iterate l_
End
End l_
 
Return timezones.0
End
Exit
/*
A "HERE" document, sort of...
Everything between the __DATA__ and __ENDD__ delimiters will be read into the timezones. stem:
 
__DATA__
{Universal}
UTC  ! Coordinated Universal Time  !  ! 0
 
{Europe}
BST  ! British Summer Time  !  ! +1
CEST ! Central European Summer Time  !  ! +2
CET  ! Central European Time  !  ! +1
EEST ! Eastern European Summer Time  !  ! +3
EET  ! Eastern European Time  !  ! +2
GMT  ! Greenwich Mean Time  !  ! 0
IST  ! Irish Standard Time  !  ! +1
KUYT ! Kuybyshev Time  !  ! +4
MSD  ! Moscow Daylight Time  !  ! +4
MSK  ! Moscow Standard Time  !  ! +3
SAMT ! Samara Time  !  ! +4
WEST ! Western European Summer Time  !  ! +1
WET  ! Western European Time  !  ! 0
 
{North America}
ADT  ! Atlantic Daylight Time  ! HAA  ! -3
AKDT ! Alaska Daylight Time  ! HAY  ! -8
AKST ! Alaska Standard Time  ! HNY  ! -9
AST  ! Atlantic Standard Time  ! HNA  ! -4
CDT  ! Central Daylight Time  ! HAC  ! -5
CST  ! Central Standard Time  ! HNC  ! -6
EDT  ! Eastern Daylight Time  ! HAE  ! -4
EGST ! Eastern Greenland Summer Time  !  ! 0
EGT  ! East Greenland Time  !  ! -1
EST  ! Eastern Standard Time  ! HNE,ET ! -5
HADT ! Hawaii-Aleutian Daylight Time  !  ! -9
HAST ! Hawaii-Aleutian Standard Time  !  ! -10
MDT  ! Mountain Daylight Time  ! HAR  ! -6
MST  ! Mountain Standard Time  ! HNR  ! -7
NDT  ! Newfoundland Daylight Time  ! HAT  ! -2.5
NST  ! Newfoundland Standard Time  ! HNT  ! -3.5
PDT  ! Pacific Daylight Time  ! HAP  ! -7
PMDT ! Pierre & Miquelon Daylight Time  !  ! -2
PMST ! Pierre & Miquelon Standard Time  !  ! -3
PST  ! Pacific Standard Time  ! HNP,PT ! -8
WGST ! Western Greenland Summer Time  !  ! -2
WGT  ! West Greenland Time  !  ! -3
 
{India and Indian Ocean}
IST  ! India Standard Time  !  ! +5.5
PKT  ! Pakistan Standard Time  !  ! +5
BST  ! Bangladesh Standard Time  !  ! +6 -- Note: collision with British Summer Time
NPT  ! Nepal Time  !  ! +5.75
BTT  ! Bhutan Time  !  ! +6
BIOT ! British Indian Ocean Territory Time ! IOT  ! +6
MVT  ! Maldives Time  !  ! +5
CCT  ! Cocos Islands Time  !  ! +6.5
TFT  ! French Southern and Antarctic Time  !  ! +5
 
__ENDD__
*/

 
Output:
Manipulate the date string "March 7 2009 7:30pm EST" and present results in ISO 8601 timestamp format:

Original date:
2009-03-07T19:30:00.000000-0500

Result after adding 12 hours to date:
2009-03-08T07:30:00.000000-0500

Result shifted to "UTC (Zulu)" time zone:
2009-03-08T00:30:00.000000Z

Result shifted to "Pacific Standard Time" time zone:
2009-03-08T04:30:00.000000-0800

Result shifted to "Nepal Time" time zone:
2009-03-08T18:15:00.000000+0545

Pascal[edit]

See Delphi

Perl[edit]

We use Mountain Daylight Time for output.

use DateTime;
use DateTime::Format::Strptime 'strptime';
use feature 'say';
 
my $input = 'March 7 2009 7:30pm EST';
$input =~ s{EST}{America/New_York};
 
say strptime('%b %d %Y %I:%M%p %O', $input)
->add(hours => 12)
->set_time_zone('America/Edmonton')
->format_cldr('MMMM d yyyy h:mma zzz');

If we're given an ambiguous timezone like 'EST' for input, we can handle this by changing it to the unambiguous Olson timezone id. This ensures daylight savings is correctly handled (which is especially tricky here, since March 7/8 is the DST rollover, and times jump ahead skipping an hour)

Output:
March 8 2009 6:30AM MDT

Perl 6[edit]

Perl 6 comes with a build-in DateTime type to support most aspects of standard civic time calculation that are not dependent on cultural idiosyncracies.
Unfortunately, Perl 6 does not yet have a date parsing module (mostly due to a reticence to inflict Western cultural imperialism on other cultures... or maybe just due to laziness), but that just gives us another opportunity to demonstrate the built-in grammar support.

my @month = <January February March April May June July August September October November December>;
my %month = flat (@month Z=> ^12), (@month».substr(0,3) Z=> ^12), 'Sept' => 8;
 
grammar US-DateTime {
rule TOP { <month> <day>','? <year>','? <time> <tz> }
 
token month {
(\w+)'.'? { make %month{$0} // die "Bad month name: $0" }
}
 
token day { (\d ** 1..2) { make +$0 } }
 
token year { (\d ** 1..4) { make +$0 } }
 
token time {
(\d ** 1..2) ':' (\d ** 2) \h* ( :i <[ap]> \.? m | '' )
{
my $h = $0 % 12;
my $m = $1;
$h += 12 if $2 and $2.substr(0,1).lc eq 'p';
make $h * 60 + $m;
}
}
 
token tz { # quick and dirty for this task
[
| EDT { make -4 }
| [ EST| CDT] { make -5 }
| [ CST| MDT] { make -6 }
| [ MST| PDT] { make -7 }
| [ PST|AKDT] { make -8 }
| [AKST|HADT] { make -9 }
| HAST
]
}
}
 
$/ = US-DateTime.parse('March 7 2009 7:30pm EST') or die "Can't parse date";
 
my $year = $<year>.ast;
my $month = $<month>.ast;
my $day = $<day>.ast;
my $hour = $<time>.ast div 60;
my $minute = $<time>.ast mod 60;
my $timezone = $<tz>.ast * 3600;
 
my $dt = DateTime.new(:$year, :$month, :$day, :$hour, :$minute, :$timezone).in-timezone(0);
 
$dt = $dt.later(hours => 12);
 
say "12 hours later, GMT: $dt";
say "12 hours later, PST: $dt.in-timezone(-8 * 3600)";
Output:
12 hours later, GMT: 2009-02-08T12:30:00Z
12 hours later, PST: 2009-02-08T04:30:00-0800

Phix[edit]

include builtins\timedate.e
set_timedate_formats({"Mmmm d yyyy h:mmpm tz"})
timedate td = parse_date_string("March 7 2009 7:30pm EST")
atom twelvehours = timedelta(hours:=12)
td = adjust_timedate(td,twelvehours)
?format_timedate(td)
td = change_timezone(td,"ACDT") -- extra credit
?format_timedate(td)
td = adjust_timedate(td,timedelta(days:=31*4))
?format_timedate(td)
Output:
"March 8 2009 7:30am EST"
"March 8 2009 11:00pm ACDT"
"July 10 2009 10:00pm ACST"

PHP[edit]

<?php
$time = new DateTime('March 7 2009 7:30pm EST');
$time->modify('+12 hours');
echo $time->format('c');
?>

PicoLisp[edit]

(de timePlus12 (Str)
(use (@Mon @Day @Year @Time @Zone)
(and
(match
'(@Mon " " @Day " " @Year " " @Time " " @Zone)
(chop Str) )
(setq @Mon (index (pack @Mon) *MonFmt))
(setq @Day (format @Day))
(setq @Year (format @Year))
(setq @Time
(case (tail 2 @Time)
(("a" "m") ($tim (head -2 @Time)))
(("p" "m") (+ `(time 12 0) ($tim (head -2 @Time))))
(T ($tim @Time)) ) )
(let? Date (date @Year @Mon @Day)
(when (>= (inc [email protected] `(time 12 0)) 86400)
(dec [email protected] 86400)
(inc 'Date) )
(pack (dat$ Date "-") " " (tim$ @Time T) " " @Zone) ) ) ) )

Pike[edit]

> (Calendar.dwim_time("March 7 2009 7:30pm EST")+Calendar.Hour()*12)->set_timezone("CET")->format_ext_time();
Result: "Saturday, 7 March 2009 12:30:00"

PL/I[edit]

/* The PL/I date functions handle dates and time in 49             */
/* different formats, but not that particular one. For any of the */
/* standard formats, the following date manipulation will add */
/* 12 hours to the current date/time. */
 
seconds = SECS(DATETIME());
seconds = seconds + 12*60*60;
put list (SECSTODATE(seconds));

PowerShell[edit]

The .NET framework does not support parsing of time zone identifiers like "EST". We have to use time zone offsets like "-5".

$date = [DateTime]::Parse("March 7 2009 7:30pm -5" )
write-host $date
write-host $date.AddHours(12)
write-host [TimeZoneInfo]::ConvertTimeBySystemTimeZoneId($date.AddHours(12),"Vladivostok Standard Time")
Output:
(depends on user regional settings):
domingo, 08 de marzo de 2009 1:30:00
domingo, 08 de marzo de 2009 13:30:00
domingo, 08 de marzo de 2009 23:30:00

PureBasic[edit]

 
EnableExplicit
 
Procedure.i ToPBDate(Date$, *zone.String)
Protected year, month, day, hour, minute
Protected month$, temp$, time$, pm$, zone$
month$ = StringField(date$, 1, " ")
day = Val(StringField(date$, 2, " "))
year = Val(StringField(date$, 3, " "))
time$ = StringField(date$, 4, " ")
zone$ = StringField(date$, 5, " ")
 
Select month$
Case "January"  : month = 1
Case "February"  : month = 2
Case "March"  : month = 3
Case "April"  : month = 4
Case "May"  : month = 5
Case "June"  : month = 6
Case "July"  : month = 7
Case "August"  : month = 8
Case "September" : month = 9
Case "October"  : month = 10
Case "November"  : month = 11
Case "December"  : month = 12
EndSelect
 
hour = Val(StringField(time$, 1, ":"))
temp$ = StringField(time$, 2, ":")
minute = Val(Left(temp$, 2))
pm$ = Right(temp$, 2)
 
If pm$ = "am"
If hour = 12 : hour = 0 : EndIf
Else
If hour <> 12 : hour + 12 : EndIf
EndIf
 
*zone\s = zone$
ProcedureReturn Date(year, month, day, hour, minute, 0)
EndProcedure
 
Procedure.s FromPBDate(Date, zone$)
Protected year$ = Str(Year(Date))
Protected month = Month(Date)
Protected day$ = Str(Day(Date))
Protected hour = Hour(Date)
Protected minute = Minute(Date)
Protected month$, time$, pm$, result$
 
Select month
Case 1  : month$ = "January"
Case 2  : month$ = "February"
Case 3  : month$ = "March"
Case 4  : month$ = "April"
Case 5  : month$ = "May"
Case 6  : month$ = "June"
Case 7  : month$ = "July"
Case 8  : month$ = "August"
Case 9  : month$ = "September"
Case 10 : month$ = "October"
Case 11 : month$ = "November"
Case 12 : month$ = "December"
EndSelect
 
If hour > 12
hour - 12
pm$ = "pm"
ElseIf hour = 12
pm$ = "pm"
Else
If hour = 0 : hour = 12 : EndIf
pm$ = "am"
EndIf
 
time$ = Str(hour) + ":" + RSet(Str(minute), 2, "0") + pm$
result$ = month$ + " " + day$ + " " + year$ + " " + time$ + " " + zone$
ProcedureReturn result$
EndProcedure
 
Define date
Define date1$, date2$
Define zone.String
 
If OpenConsole()
date1$ = "March 7 2009 7:30pm EST"
PrintN("Starting date/time : " + date1$)
date = ToPBDate(date1$, @zone)
date = AddDate(date, #PB_Date_Hour, 12); add 12 hours
date2$ = FromPBDate(date, zone\s)
PrintN("12 hours later  : " + date2$)
date = AddDate(date, #PB_Date_Hour, 5); adjust to GMT
date2$ = FromPBDate(date, "GMT")
PrintN("Or in GMT timezone : " + date2$)
PrintN("")
PrintN("Press any key to close the console")
Repeat: Delay(10) : Until Inkey() <> ""
CloseConsole()
EndIf
 
Output:
Starting date/time : March 7 2009 7:30pm EST
12 hours later     : March 8 2009 7:30am EST
Or in GMT timezone : March 8 2009 12:30pm GMT

Python[edit]

I don't do anything with timezone here, but it is possible.

import datetime
 
def mt():
datime1="March 7 2009 7:30pm EST"
formatting = "%B %d %Y %I:%M%p "
datime2 = datime1[:-3] # format can't handle "EST" for some reason
tdelta = datetime.timedelta(hours=12) # twelve hours..
s3 = datetime.datetime.strptime(datime2, formatting)
datime2 = s3+tdelta
print datime2.strftime("%B %d %Y %I:%M%p %Z") + datime1[-3:]
 
mt()

R[edit]

time <- strptime("March 7 2009 7:30pm EST", "%B %d %Y %I:%M%p %Z") # "2009-03-07 19:30:00"
isotime <- ISOdatetime(1900 + time$year, time$mon, time$mday,
time$hour, time$min, time$sec, "EST") # "2009-02-07 19:30:00 EST"
twelvehourslater <- isotime + 12 * 60 * 60 # "2009-02-08 07:30:00 EST"
timeincentraleurope <- format(isotime, tz="CET", usetz=TRUE) #"2009-02-08 01:30:00 CET"

Racket[edit]

The solution below ignores the time zone.

 
#lang racket
(require srfi/19)
 
(define 12hours (make-time time-duration 0 (* 12 60 60)))
 
(define (string->time s)
(define t (date->time-utc (string->date s "~B~e~Y~H~M")))
(if (regexp-match "pm" s)
(add-duration t 12hours)
t))
 
(date->string
(time-utc->date
(add-duration
(string->time "March 7 2009 7:30pm est" )
12hours))
"~a ~d ~b ~Y ~H:~M")
 
Output:
 
"Sun 08 Mar 2009 07:30"
 

REBOL[edit]

rebol [
Title: "Date Manipulation"
Author: oofoe
Date: 2009-12-06
URL: http://rosettacode.org/wiki/Date_Manipulation
]

 
; Only North American zones here -- feel free to extend for your area.
 
zones: [
NST -3:30 NDT -2:30 AST -4:00 ADT -3:00 EST -5:00 EDT -4:00
CST -6:00 CDT -5:00 MST -7:00 MDT -6:00 PST -8:00 PDT -7:00 AKST -9:00
AKDT -8:00 HAST -10:00 HADT -9:00]
 
read-time: func [
text
/local m d y t z
][
parse load text [
set m word! (m: index? find system/locale/months to-string m)
set d integer! set y integer!
set t time! set tz word!]
to-date reduce [y m d t zones/:tz]
]
 
print 12:00 + read-time "March 7 2009 7:30pm EST"
 
Output:
8-Mar-2009/7:30-5:00

REXX[edit]

This version only works with REXXes that support the   date   and   time   extended functions.

/*REXX program adds 12 hours to a  given date and time, displaying the before and after.*/
aDate = 'March 7 2009 7:30pm EST' /*the original or base date to be used.*/
 
parse var aDate mon dd yyyy hhmm tz . /*obtain the various parts and pieces. */
 
mins = time('M', hhmm, "C") /*get the number minutes past midnight.*/
mins = mins + (12*60) /*add twelve hours to the timestamp.*/
nMins = mins // 1440 /*compute number min into same/next day*/
days = mins % 1440 /*compute number of days added to dats.*/
aBdays = date('B', dd left(mon,3) yyyy) /*number of base days since REXX epoch.*/
nBdays = aBdays + days /*now, add the number of days added. */
nDate = date(,nBdays, 'B') /*calculate the new date (maybe). */
nTime = time('C', nMins, "M") /* " " " time " */
 
say aDate ' + 12 hours ───► ' ndate ntime tz /*display the new timestamp to console.*/
/*stick a fork in it, we're all done. */

output

March 7 2009 7:30pm EST  +  12 hours  ───►  8 Mar 2009 7:30am EST

Ruby[edit]

Time class[edit]

The Time package in the standard library adds a parse method to the core Time class.

Library: ActiveSupport
require 'time'
d = "March 7 2009 7:30pm EST"
t = Time.parse(d)
puts t.rfc2822
puts t.zone
 
new = t + 12*3600
puts new.rfc2822
puts new.zone
 
# another timezone
require 'rubygems'
require 'active_support'
zone = ActiveSupport::TimeZone['Beijing']
remote = zone.at(new)
# or, remote = new.in_time_zone('Beijing')
puts remote.rfc2822
puts remote.zone
Output:
Sat, 07 Mar 2009 19:30:00 -0500
EST
Sun, 08 Mar 2009 08:30:00 -0400
EDT
Sun, 08 Mar 2009 20:30:00 +0800
CST

Using ActiveSupport, we can add 12 hours with any of:

new = t + 12.hours
new = t.in(12.hours)
new = t.advance(:hours => 12)

DateTime class[edit]

require "date"
 
puts d1 = DateTime.parse("March 7 2009 7:30pm EST")
# d1 + 1 would add a day, so add half a day:
puts d2 = d1 + 1/2r # 1/2r is a rational; 0.5 would also work
puts d3 = d2.new_offset('+09:00')
Output:
2009-03-07T19:30:00-05:00
2009-03-08T07:30:00-05:00
2009-03-08T21:30:00+09:00

Run BASIC[edit]

theDate$ = "March 7 2009 7:30pm EST"
 
monthName$ = "January February March April May June July August September October November December"
for i = 1 to 12
if word$(theDate$,1) = word$(monthName$,i) then monthNum = i ' turn month name to number
next i
d = val(date$(monthNum;"/";word$(theDate$,2);"/";word$(theDate$,3))) ' days since Jan 1 1901
t$ = word$(theDate$,4) ' get time from theDate$
t1$ = word$(t$,1,"pm") ' strip pm
t2$ = word$(t1$,1,":") + "." + word$(t1$,2,":") ' replace : with .
t = val(t2$)
if right$(t$,2) = "pm" then t = t + 12
ap$ = "pm"
if t + 12 > 24 then
d = d + 1 ' if over 24 hours add 1 to days since 1/1/1901
ap$ = "am"
end if
print date$(d);" ";t1$;ap$
03/08/2009 7:30am

Scala[edit]

import java.text.SimpleDateFormat
import java.util.{Calendar, Locale, TimeZone}
 
object DateManipulation {
def main(args: Array[String]): Unit = {
val input="March 7 2009 7:30pm EST"
val df=new SimpleDateFormat("MMMM d yyyy h:mma z", Locale.ENGLISH)
val c=Calendar.getInstance()
c.setTime(df.parse(input))
 
c.add(Calendar.HOUR_OF_DAY, 12)
println(df.format(c.getTime))
 
df.setTimeZone(TimeZone.getTimeZone("GMT"))
println(df.format(c.getTime))
}
}
Output:
March 8 2009 8:30AM EDT
March 8 2009 12:30PM GMT

Seed7[edit]

Time zone identifiers like "EST" are ambiguous. E.g.: "AST" is used to abbreviate both Atlantic Standard Time (UTC-04) and Arab Standard Time (UTC+03). Therefore parsing of such time zone identifiers is not supported by Seed7. ISO 8601 defines no time zone designators. Instead ISO 8601 specifies time offsets from UTC. In the example below EST is replaced with UTC-05.

$ include "seed7_05.s7i";
include "time.s7i";
include "duration.s7i";
 
const func time: parseDate (in string: dateStri) is func
result
var time: result is time.value;
local
const array string: monthNames is [] ("January", "February", "March", "April",
"May", "June", "July", "August", "September", "October", "November", "December");
var array string: dateParts is 0 times "";
var integer: month is 0;
var string: timeStri is "";
begin
dateParts := split(dateStri, ' ');
result.year := integer parse (dateParts[3]);
result.month := 1;
while monthNames[result.month] <> dateParts[1] do
incr(result.month);
end while;
result.day := integer parse (dateParts[2]);
timeStri := dateParts[4];
if endsWith(timeStri, "am") then
result.hour := integer parse (timeStri[.. pred(pos(timeStri, ':'))]);
elsif endsWith(timeStri, "pm") then
result.hour := integer parse (timeStri[.. pred(pos(timeStri, ':'))]) + 12;
else
raise RANGE_ERROR;
end if;
result.minute := integer parse (timeStri[succ(pos(timeStri, ':')) .. length(timeStri) - 2]);
if dateParts[5] <> "UTC" then
result.timeZone := 60 * integer parse (dateParts[5][4 ..]);
end if;
end func;
 
const proc: main is func
local
var time: aTime is time.value;
begin
aTime := parseDate("March 7 2009 7:30pm UTC-05");
writeln("Given: " <& aTime);
aTime +:= 1 . DAYS;
writeln("A day later: " <& aTime);
aTime := toUTC(aTime);
writeln("In UTC: " <& aTime);
end func;
Output:
Given:         2009-03-07 19:30:00 UTC-5
A day later:   2009-03-08 19:30:00 UTC-5
In UTC:        2009-03-09 00:30:00 UTC

Sidef[edit]

Translation of: Perl
var dt = frequire('DateTime::Format::Strptime')
 
var input = 'March 7 2009 7:30pm EST'
input.sub!('EST', 'America/New_York')
 
say dt.strptime('%b %d %Y %I:%M%p %O', input) \
.add(hours => 12) \
.set_time_zone('America/Edmonton') \
.format_cldr('MMMM d yyyy h:mma zzz')
Output:
March 8 2009 6:30AM MDT

Smalltalk[edit]

Works with: GNU Smalltalk

The aim of the class DateTimeTZ is to provide the ability to understand time with "meridian" (PM/AM, even though no checks are done to assure coherency of the format) and to handle timezones despite the locale (which anyway is gently "ignored", or rather unknown in the format of letters, to Date), providing a proper set of informations to the method readFromWithMeridian:andTimeZone:.

The aDict argument must be a dictionary where keys are the abbreviated timezone code (e.g. EST), and values are three-elements array: difference between the timezone and GMT (as Duration), the DateTime when there's passage between using or not using the daylight saving time (year is ignored), and the "direction" (as Duration) of the change. All data must be filled by hand... As example I've put EST (and there's no way to represent the "new" date and time correctly with the new EDT timezone).

The code also fails when adding a duration that "jumps" beyond two DST changes (e.g from EST to EDT and EST again); (it could be partially fixed by considering intervals instead of single date, and adding a fourth element to link to the "new" timezone abbreviation)

DateTime extend [
setYear: aNum [ year := aNum ]
].
 
Object subclass: DateTimeTZ [
|dateAndTime timeZoneDST timeZoneName timeZoneVar|
 
DateTimeTZ class >> new [ ^(super basicNew) ]
 
DateTimeTZ class >> readFromWithMeridian: aStream andTimeZone: aDict [
|me|
me := self new.
^ me initWithMeridian: aStream andTimeZone: aDict
]
 
initWithMeridian: aStream andTimeZone: aDict [ |s|
dateAndTime := DateTime readFrom: aStream copy.
s := aStream collection asString.
s =~ '[pP][mM]'
ifMatched: [ :m |
dateAndTime := dateAndTime + (Duration days: 0 hours: 12 minutes: 0 seconds: 0)
].
aDict keysAndValuesDo: [ :k :v |
s =~ k
ifMatched: [ :x |
dateAndTime := dateAndTime setOffset: (v at: 1).
timeZoneDST := (v at: 2) setOffset: (v at: 1).
timeZoneVar := (v at: 3).
timeZoneDST setYear: (self year). "ignore the year"
timeZoneName := k
]
].
^ self
]
 
setYear: aNum [ dateAndTime setYear: aNum ]
year [ ^ dateAndTime year ]
 
timeZoneName [ ^timeZoneName ]
 
+ aDuration [ |n|
n := dateAndTime + aDuration.
(n > timeZoneDST) ifTrue: [ n := n + timeZoneVar ].
^ (self copy dateTime: n)
]
 
dateTime [ ^dateAndTime ]
dateTime: aDT [ dateAndTime := aDT ]
 
].

Usage example (note: the code is rather rigid, so not all operations possible on DateTime are possible on DateTimeTZ).

|s abbrDict dt|
 
s := 'March 7 2009 7:30pm EST'.
 
"Build a abbreviation -> offset for timezones (example)"
abbrDict := Dictionary new.
 
abbrDict at: 'EST'
put: { (Duration days: 0 hours: -5 minutes: 0 seconds: 0).
(DateTime year: 2009 month: 3 day: 8 hour: 2 minute: 0 second: 0).
(Duration days: 0 hours: 1 minutes: 0 seconds: 0) }.
 
dt := DateTimeTZ readFromWithMeridian: (s readStream) andTimeZone: abbrDict.
 
dt := dt + (Duration days: 0 hours: 12 minutes: 0 seconds: 0).
 
"let's print it"
('%1 %2 %3 %4:%5%6 %7' %
{
(dt dateTime) monthName asString.
(dt dateTime) day.
(dt dateTime) year.
(dt dateTime) hour12.
(dt dateTime) minute.
(dt dateTime) meridianAbbreviation asString.
dt timeZoneName.
}) displayNl.
 
(dt dateTime) asUTC displayNl.
Output:
(note that EST should be EDT):
March 8 2009 8:30AM EST
 2009-03-08T13:30:00+00:00

Tcl[edit]

Works with: Tcl version 8.5
set date "March 7 2009 7:30pm EST"
set epoch [clock scan $date -format "%B %d %Y %I:%M%p %z"]
set later [clock add $epoch 12 hours]
puts [clock format $later] ;# Sun Mar 08 08:30:00 EDT 2009
puts [clock format $later -timezone :Asia/Shanghai] ;# Sun Mar 08 20:30:00 CST 2009

Note the transition into daylight savings time in the interval (in the Eastern timezone).

UNIX Shell[edit]

requires GNU date

epoch=$(date -d 'March 7 2009 7:30pm EST +12 hours' +%s)
date -d @$epoch
TZ=Asia/Shanghai date -d @$epoch
Output:
Sun Mar  8 08:30:00 EDT 2009
Sun Mar  8 20:30:00 CST 2009

zkl[edit]

The iso8601 library offers additional Time/Date support but using the built in stuff:

var Date=Time.Date;
fcn add12h(dt){
re:=RegExp(0'|(\w+)\s+(\d+)\s+(\d+)\ +(.+)\s|);
re.search(dt);
_,M,D,Y,hms:=re.matched; //"March","7","2009","7:30pm"
M=Date.monthNames.index(M); //3
h,m,s:=Date.parseTime(hms); //19,30,0
dti:=T(Y,M,D, h,m,s).apply("toInt");
Y,M,D, h,m,s=Date.addHMS(dti,12);
"%s %d %d %s".fmt(Date.monthNames[M],D,Y,Date.toAMPMString(h,m));
}
add12h("March 7 2009 7:30pm EST").println();
Output:
March 8 2009 07:30AM