Date manipulation

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Revision as of 00:08, 14 March 2020 by Thundergnat (talk | contribs) (Rename Perl 6 -> Raku, alphabetize, minor clean-up)
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.

11l

<lang 11l>V format_str = ‘%B %d %Y %I:%M%p’ print((time:strptime(‘March 7 2009 7:30pm’, format_str)

    + TimeDelta(hours' 12)).strftime(format_str))</lang>

Ada

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

<lang Ada>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;</lang>

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

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. <lang AppleScript>set x to "March 7 2009 7:30pm EST" return (date x) + 12 * hours</lang>

Result is: <lang AppleScript>date "Sunday, March 8, 2009 7:30:00 AM"</lang>

The above is problematical in that:

  1. Using a date string in an AppleScript date specifier only works if the date format set in the user's preferences on the host machine is the same as the one used in the string.
  2. The US clocks went forward in the twelve hours specified by the task and, as already noted, vanilla AppleScript has no way of dealing with that.


However, AppleScript can run shell scripts and, more recently, access some of the system's Objective-C API through its hybrid form AppleScriptObjectiveC. So as long as the date format's known, the task is doable:

<lang applescript>use AppleScript version "2.4" -- OS X 10.10 (Yosemite) or later use framework "Foundation"

on dateManipulationTask()

   set dateString to "March 7 2009 7:30pm EST"
   
   set dateFormatter to current application's class "NSDateFormatter"'s new()
   tell dateFormatter to setDateFormat:("MMMM d yyyy h:mma z")
   tell dateFormatter to setAMSymbol:("am")
   tell dateFormatter to setPMSymbol:("pm")
   set USLocale to current application's class "NSLocale"'s localeWithLocaleIdentifier:("en_US")
   tell dateFormatter to setLocale:(USLocale)
   set timeZone to current application's class "NSTimeZone"'s timeZoneWithAbbreviation:(last word of dateString)
   tell dateFormatter to setTimeZone:(timeZone)
   
   set inputDate to dateFormatter's dateFromString:(dateString)
   set newDate to current application's class "NSDate"'s dateWithTimeInterval:(12 * hours) sinceDate:(inputDate)
   
   return (dateFormatter's stringFromDate:(newDate)) as text

end dateManipulationTask

dateManipulationTask()</lang>

Output:
"March 8 2009 8:30am EDT"

AutoHotkey

<lang autohotkey>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

}</lang>

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

<lang AWK>

  1. 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)

} </lang>

Output:
time:    Sat 2009-03-07 19:30:00 Eastern Standard Time
+12 hrs: Sun 2009-03-08 08:30:00 Eastern Daylight Time

Batch File

<lang dos> @echo off

call:Date_Manipulation "March 7 2009 7:30pm EST" call:Date_Manipulation "February 28 2009 2:28pm EST" call:Date_Manipulation "February 29 2000 9:52pm EST" pause>nul exit /b

Date_Manipulation

setlocal enabledelayedexpansion

These are the arrays we'll be using

set daysinmonth=31 28 31 30 31 30 31 31 30 31 30 31 set namesofmonths=January February March April May June July August September October November December

Separate the date given ("%1") into respective variables. Note: For now the "am/pm" is attached to %minutes%

for /f "tokens=1,2,3,4,5,6 delims=: " %%i in ("%~1") do (

 set monthname=%%i
 set day=%%j
 set year=%%k
 set hour=%%l
 set minutes=%%m
 set timezone=%%n

)

Separate the am/pm and the minutes value into different variables

set ampm=%minutes:~2,2% set minutes=%minutes:~0,2%

Check if the day needs to be changed based on the status of "am/pm"

if %ampm%==pm (

 set /a day+=1
 set ampm=am

) else (

 set ampm=pm

)

Get the number corresponding to the month given

set tempcount=0 for %%i in (%namesofmonths%) do (

 set /a tempcount+=1
 if %monthname%==%%i set monthcount=!tempcount!

)

As this step may may be needed to repeat if the month needs to be changed, we add a label here
getdaysinthemonth
Work out how many days are in the current month

set tempcount=0 for %%i in (%daysinmonth%) do (

 set /a tempcount+=1
 if %monthcount%==!tempcount! set daysinthemonth=%%i

)

If the month is February, check if it is a leap year. If so, add 1 to the amount of days in the month

if %daysinthemonth%==28 (

 set /a leapyearcheck=%year% %% 4
 if !leapyearcheck!==0 set /a daysinthemonth+=1

)

Check if the month needs to be changed based on the current day and how many days there are in the current month

if %day% gtr %daysinthemonth% (

 set /a monthcount+=1
 set day=1
 if !monthcount! gtr 12 (
   set monthcount=1
   set /a year+=1
 )
 goto getdaysinthemonth

)

Everything from :getdaysinthemonth will be repeated once if the month needs to be changed
This block is only required to change the name of the month for the output, however as you have %monthcount%, this is optional

set tempcount=0 for %%i in (%namesofmonths%) do (

 set /a tempcount+=1
 if %monthcount%==!tempcount! set monthname=%%i

)

echo Original - %~1 echo Manipulated - %monthname% %day% %year% %hour%:%minutes%%ampm% %timezone% exit /b </lang> The code takes 3 inputs to demonstrate the ability to deal with leap years.

Input:
"March 7 2009 7:30pm EST"
"February 28 2009 2:28pm EST"
"February 29 2000 9:52pm EST"
Output:
Original    - March 7 2009 7:30pm EST
Manipulated - March 8 2009 7:30am EST
Original    - February 28 2009 2:28pm EST
Manipulated - March 1 2009 2:28am EST
Original    - February 29 2000 9:52pm EST
Manipulated - March 1 2000 9:52am EST

BBC BASIC

<lang bbcbasic> 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

</lang>

Output:
March 8 2009 7:30am EST
March 8 2009 12:30pm GMT
March 8 2009 4:30am PST

C

Works with: POSIX

<lang c>#include <stdio.h>

  1. include <stdlib.h>
  2. 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;

}</lang>

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#

<lang csharp>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();
   }

}</lang>

C++

Library: Boost

compiled with g++ -lboost_date_time <lang cpp>#include <string>

  1. include <iostream>
  2. include <boost/date_time/local_time/local_time.hpp>
  3. include <sstream>
  4. include <boost/date_time/gregorian/gregorian.hpp>
  5. include <vector>
  6. include <boost/algorithm/string.hpp>
  7. include <cstdlib>
  8. 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 ;

} </lang>

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

<lang Clojure>(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 ,)))))</lang>

COBOL

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.

<lang cobol> 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.

</lang>

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

D

<lang d> import std.stdio; import std.format; import std.datetime; import std.algorithm;

enum months = ["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"];

void main() {

 // input	
 string date = "March 7 2009 7:30pm EST";
 // parsing date string to integer values
 string month, md, tz;
 int day, year, hour, minute;
 date.formattedRead("%s %d %d %d:%d%s %s", &month, &day, &year, &hour, &minute, &md, &tz);
 int mon = cast (int) months.countUntil(month) + 1;
 // convert to 24-hour 
 if (md == "pm")
   hour += 12;
 // create date from integer
 DateTime dt = DateTime(year, mon, day, hour, minute);
 // output
 writeln(dt);
 writeln(dt + 12.hours);

}

</lang>

Output:
2009-Mar-07 19:30:00
2009-Mar-08 07:30:00

Delphi

<lang Delphi> 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. </lang>

Output:
"03/08/2009 07:30 AM"

EchoLisp

<lang scheme> (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.

</lang>


Erlang

It is human readable to me. <lang Erlang> -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. </lang>

Output:
24> date_manipulation:task().
{{{2009,3,8},{7,30,0}},"EST"}

Euphoria

<lang Euphoria> --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")}) </lang>

Output:
March 08 2009 07:30 AM EST

F#

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

<lang fsharp>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()</lang>

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

Factor

<lang factor>USING: calendar calendar.english calendar.format calendar.parser combinators io kernel math math.parser sequences splitting unicode ; IN: rosetta-code.date-manipulation

! e.g. "7:30pm" -> 19 30

parse-hm ( str -- hours minutes )
   ":" split first2 [ digit? ] partition
   [ [ string>number ] bi@ ] dip "pm" = [ [ 12 + ] dip ] when ;

! Parse a date in the format "March 7 2009 7:30pm EST"

parse-date ( str -- timestamp )
   " " split {
       [ first month-names index 1 + ]
       [ second string>number ]
       [ third string>number -rot ]
       [ fourth parse-hm 0 ]
       [ last parse-rfc822-gmt-offset ]
   } cleave <timestamp> ;

"March 7 2009 7:30pm EST" parse-date dup 12 hours time+ [ timestamp>rfc822 print ] bi@</lang>

Output:
Sat, 7 Mar 2009 19:30:00 -0500
Sun, 8 Mar 2009 07:30:00 -0500

Fantom

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

<lang fantom> 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 </lang>

FreeBASIC

<lang freebasic>' FB 1.05.0 Win64

  1. include "vbcompat.bi"

Sub split (s As String, sepList As String, result() As String, removeEmpty As Boolean = False)

 If s = "" OrElse sepList = "" Then 
    Redim result(0)
    result(0) = s
    Return
 End If
 Dim As Integer i, j, count = 0, empty = 0, length
 Dim As Integer position(Len(s) + 1)
 position(0) = 0

 For i = 0 To len(s) - 1
   For j = 0 to Len(sepList) - 1
     If s[i] = sepList[j] Then 
       count += 1
       position(count) = i + 1       
     End If
   Next j
 Next i
 Redim result(count)
 If count  = 0 Then
   result(0) = s
   Return
 End If
 position(count + 1) = len(s) + 1

 For i = 1 To count + 1  
   length = position(i) - position(i - 1) - 1 
   result(i - 1 - empty) = Mid(s, position(i - 1) + 1, length)
   If removeEmpty Andalso CBool(length = 0) Then empty += 1
 Next
 If empty > 0 Then Redim Preserve result(count - empty)

End Sub

Function parseDate(dt As String, zone As String) As Double

 Dim result() As String
 split dt, " ", result(), True
 Dim As Long m, d, y, h, mn
 Dim am As Boolean
 Dim index As Integer 
 Select Case Lcase(result(0))
   Case "january"    : m = 1
   Case "february"   : m = 2
   Case "march"      : m = 3
   Case "april"      : m = 4
   Case "may"        : m = 5
   Case "june"       : m = 6
   Case "july"       : m = 7
   Case "august"     : m = 8
   Case "september"  : m = 9
   Case "october"    : m = 10
   Case "november"   : m = 11
   Case "december"   : m = 12
 End Select
 d = ValInt(result(1))
 y = ValInt(result(2))
 result(3) = LCase(result(3))
 am = (Right(result(3), 2) = "am")
 index = Instr(result(3), ":")
 h = ValInt(Left(result(3), index - 1))
 If Not am Then 
   h = h + 12
   If h = 24 Then h = 12
 End If 
 mn = ValInt(Mid(result(3), index + 1, 2))
 zone = result(4)
 Return DateSerial(y, m, d) + TimeSerial(h, mn, 0)

End Function

Dim zone As String Dim ds As Double = parseDate("March 7 2009 7:30pm EST", zone) Print "Original Date/Time  : "; Format(ds, "mmmm d yyyy h:nnam/pm ") + " " + zone ds = DateAdd("h", 12, ds) Print "12 hours later  : "; Format(ds, "mmmm d yyyy h:nnam/pm ") + " " + zone ' add 5 hours to convert EST to UTC ds = DateAdd("h", 5, ds) Print "Equiv to Date/Time  : "; Format(ds, "mmmm d yyyy h:nnam/pm ") + " UTC" Print Print "Press any key to quit" Sleep</lang>

Output:
Original Date/Time  : March 7 2009 7:30pm   EST
12 hours later      : March 8 2009 7:30am   EST
Equiv to Date/Time  : March 8 2009 12:30pm  UTC

Frink

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. <lang frink>

      1. 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 </lang>

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

<lang funl>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</lang>

Output:
March 8 2009 8:30AM EDT
March 8 2009 5:30AM PDT

Fōrmulæ

In this page you can see the solution of this task.

Fōrmulæ programs are not textual, visualization/edition of programs is done showing/manipulating structures but not text (more info). Moreover, there can be multiple visual representations of the same program. Even though it is possible to have textual representation —i.e. XML, JSON— they are intended for transportation effects more than visualization and edition.

The option to show Fōrmulæ programs and their results is showing images. Unfortunately images cannot be uploaded in Rosetta Code.

Go

<lang go>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))
   }

}</lang>

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

Solution:

Library: Joda Time version 2.1

<lang groovy>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))</lang>

Output:
2009-03-07T18:30:00.000-06:00
2009-03-08T07:30:00.000-05:00
2009-03-08T12:30:00.000Z

Haskell

<lang haskell>import qualified Data.Time.Clock.POSIX as P import qualified Data.Time.Format as F

-- UTC from EST main :: IO () main = print t2

 where
   t1 =
     F.parseTimeOrError
       True
       F.defaultTimeLocale
       "%B %e %Y %l:%M%P %Z"
       "March 7 2009 7:30pm EST"
   t2 = P.posixSecondsToUTCTime $ 12 * 60 * 60 + P.utcTimeToPOSIXSeconds t1</lang>
Output:
2009-03-08 12:30:00 UTC

HicEst

<lang hicest>

  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

</lang>

Icon and Unicon

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).

<lang Icon>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</lang>

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

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:

<lang J>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=: >./@numbers getmonth=: 1 + months <./@i. 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)&([ + -@#@[ {. ])</lang>

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:

<lang J> (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</lang>

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

Java

<lang Java>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));

   }

}</lang>

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

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.

<lang JavaScript>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)
);</lang>

jq

Works with: jq version version with mktime

<lang jq>"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") </lang>

Output:

<lang sh>"March 08 2009 07:30AM EST"</lang>

Julia

without TimeZones library

<lang julia>using Dates

function main()

   dtstr = "March 7 2009 7:30pm" # Base.Dates doesn't handle "EST"
   cleandtstr = replace(dtstr, r"(am|pm)"i, "")
   dtformat = dateformat"U dd yyyy HH:MM"
   dtime = parse(DateTime, cleandtstr, dtformat) +
       Hour(12 * contains(dtstr, r"pm"i)) # add 12h for the pm
   println(Dates.format(dtime + Hour(12), dtformat))

end

main()

</lang>

Output:
March 08 2009 07:30

With TimeZones.jl

<lang julia>using Dates, TimeZones

function testdateparse()

   tzabbrev = Dict("EST" => "+0500", "CST" => "+0600", "MST" => "+0700",  "PST" => "+0800")
   dtstr = "March 7 2009 7:30pm EST"
   for (k, v) in tzabbrev
       dtstr = replace(dtstr, k => v)
   end
   dtformat = dateformat"U dd yyyy HH:MMp zzzzz"
   dtime = TimeZones.parse(ZonedDateTime, dtstr, dtformat)
   println(Dates.format(dtime, dtformat))

end

testdateparse()

</lang>

Output:
March 07 2009 07:30AM +05:00

Kotlin

<lang scala>// version 1.0.6

import java.text.SimpleDateFormat import java.util.*

fun main(args: Array<String>) {

   val dts  = "March 7 2009 7:30pm EST"
   val sdf  = SimpleDateFormat("MMMM d yyyy h:mma z")
   val dt   = sdf.parse(dts)
   val cal  = GregorianCalendar(TimeZone.getTimeZone("EST"))  // stay with EST
   cal.time = dt
   cal.add(Calendar.HOUR_OF_DAY, 12) // add 12 hours
   val fmt = "%tB %1\$td %1\$tY %1\$tl:%1\$tM%1\$tp %1\$tZ"
   println(fmt.format(cal)) // display new time
   // display time now in Mountain Standard Time which is 2 hours earlier than EST
   cal.timeZone = TimeZone.getTimeZone("MST")
   println(fmt.format(cal))

}</lang>

Output:
March 08 2009 7:30am EST
March 08 2009 5:30am MST

Lasso

<lang Lasso>local(date) = date('March 7 2009 7:30PM EST',-format='MMMM d yyyy h:mma z')

  1. date->add(-hour = 24)
  2. date->timezone = 'GMT'</lang>
Output:
March 9 2009 12:30AM GMT

Lingo

<lang lingo>---------------------------------------- -- Returns string representation of given date object in YYYY-MM-DD hh:mm:ii format -- @param {date} dateObj -- @returns {string}


on dateToDateTimeString (dateObj)

 str = ""
 s = string(dateObj.year)
 if s.length<4 then put "0000".char[1..4-s.length] before s
 put s after str
 s = string(dateObj.month)
 if s.length<2 then s = "0"&s
 put s after str
 s = string(dateObj.day)
 if s.length<2 then put "0" before s
 put s after str
 sec = dateObj.seconds  
 s = string(sec / 3600)
 sec = sec mod 3600
 if s.length<2 then put "0" before s
 put s after str
 s = string(sec / 60)
 sec = sec mod 60
 if s.length<2 then put "0" before s
 put s after str
 s = string(sec)
 if s.length<2 then put "0" before s
 put s after str
 put ":" after char 12 of str
 put ":" after char 10 of str
 put " " after char 8 of str
 put "-" after char 6 of str
 put "-" after char 4 of str
 return str

end</lang>

<lang lingo>dateStr = "March 7 2009 7:30pm EST"

-- parse string month = (offset(dateStr.word[1].char[1..3], "JanFebMarAprMayJunJulAugSepOctNovDec")-1)/3 + 1 day = integer(dateStr.word[2]) year = integer(dateStr.word[3]) t = dateStr.word[4] if t.char[t.length-1..t.length]="pm" then dh = 12 else dh = 0 t = t.char[1..t.length-2] _player.itemDelimiter = ":" hour = integer(t.item[1])+dh minute = integer(t.item[2]) tz = dateStr.word[5] -- unused

-- original date as date object dateObj = date(year,month,day) dateObj.seconds = hour*3600 + minute*60

-- add 12 hours sec = dateObj.seconds + 12*3600 newDateObj = dateObj + sec / 86400 newDateObj.seconds = sec mod 86400

-- show as YYYY-MM-DD hh:mm:ii string put dateToDateTimeString(newDateObj) -- "2009-03-08 07:30:00"</lang>

Lua

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

Output:
Sun Mar  8 07:30:00 2009

Maple

<lang Maple>twelve_hours := proc(str) local dt, zone; local months := ["January","February","March","April","May","June","July","August","September","October","November","December"]; dt := StringTools:-ParseTime("%B %d %Y %l:%M%p", str); zone := StringTools:-RegSplit(" ", str)[-1]; dt := Date(dt:-year, dt:-month, dt:-monthDay, dt:-hour, dt:-minute, timezone = zone); dt := dt + 12 * Unit(hours); printf("%s %d %d ", months[Month(dt)], DayOfMonth(dt), Year(dt)); if (HourOfDay(dt) >= 12) then printf("%d:%dpm ", HourOfDay(dt)-12, Minute(dt)); else printf("%d:%dam ", HourOfDay(dt), Minute(dt)); end if; printf(TimeZone(dt)); end proc; </lang>

Usage:

<lang>twelve_hours("March 7 2009 7:30pm EST"); twelve_hours("March 2 2009 0:10am WET"); twelve_hours("March 2 2009 6:30am AST");</lang>

Output:
March 8 2009 7:30am EST
March 2 2009 0:10pm WET
March 2 2009 6:30pm AST

Mathematica / Wolfram Language

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

mIRC Scripting Language

<lang mirc>echo -ag $asctime($calc($ctime(March 7 2009 7:30pm EST)+43200))</lang>

NetRexx

<lang NetRexx>/* 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

</lang>

Output:
March 7 2009 7:30pm EST
March 8 2009 8:30AM EDT

Nim

<lang nim>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</lang>

Output:
Sun Mar  8 07:30:00 2009

ooRexx

version 1

<lang ooRexx>

 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 </lang>

version 2

This example is written using the Open Object Rexx dialect to take advantage of the DateTime built–in class. <lang REXX>/* 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__

  • /

</lang>

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

See Delphi

Perl

We use Mountain Daylight Time for output.

<lang perl>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');</lang>

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

Phix

<lang Phix>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)</lang>

Output:
"March 8 2009 7:30am EST"
"March 8 2009 11:00pm ACDT"
"July 10 2009 10:00pm ACST"

PHP

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

PicoLisp

<lang PicoLisp>(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 ($tim @Time)) ) )
        (let? Date (date @Year @Mon @Day)
           (when (>= (inc '@Time `(time 12 0)) 86400)
              (dec '@Time 86400)
              (inc 'Date) )
           (pack (dat$ Date "-") " " (tim$ @Time T) " " @Zone) ) ) ) )</lang>

Pike

<lang Pike>> (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"</lang>

PL/I

<lang PL/I>/* 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));</lang>

PowerShell

The .NET framework does not support parsing of time zone identifiers like "EST". We have to use time zone offsets like "-5". <lang PowerShell>$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")</lang>

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

<lang PureBasic> 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 </lang>

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

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

<lang python>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()</lang>

R

<lang R>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"</lang>

Racket

The solution below ignores the time zone. <lang racket>

  1. 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")

</lang>

Output:

<lang racket> "Sun 08 Mar 2009 07:30" </lang>

Raku

(formerly Perl 6) 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.

<lang perl6>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>','? 
   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 = $

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)";</lang>

Output:
12 hours later, GMT: 2009-02-08T12:30:00Z
12 hours later, PST: 2009-02-08T04:30:00-0800

REBOL

<lang REBOL>REBOL [ Title: "Date Manipulation" 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" </lang>

Output:
8-Mar-2009/7:30-5:00

Red

<lang Red> d: 07-Mar-2009/19:30 + 12:00 print d 8-Mar-2009/7:30:00 d/timezone: 1 print d 8-Mar-2009/8:30:00+01:00</lang>

REXX

This version only works with REXXes that support the   date   and   time   extended functions. <lang REXX>/*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. */</lang>

output

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

Ring

<lang ring>

  1. Project : Date manipulation

load "stdlib.ring" dateorigin = "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 dateorigin[1] = monthname[i]
       monthnum = i
    ok	

next thedate = str2list(substr(dateorigin, " ", nl)) t = thedate[4] t1 = substr(t,"pm", "") t2 = substr(t1,":",".") t3 = number(t2) if right(t,2) = "pm"

  t3 = t3+ 12

ok ap = "pm" d = "07/03/2009" if t3 + 12 > 24

 d = adddays("07/03/2009",1)
 ap = "am"

ok see "Original - " + dateorigin + nl see "Manipulated - " + d + " " + t1 + ap + nl </lang> Output:

Original - March 7 2009 7:30pm EST
Manipulated - 08/03/2009 7:30am

Ruby

Time class

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

Library: ActiveSupport

<lang ruby>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

  1. another timezone

require 'rubygems' require 'active_support' zone = ActiveSupport::TimeZone['Beijing'] remote = zone.at(new)

  1. or, remote = new.in_time_zone('Beijing')

puts remote.rfc2822 puts remote.zone</lang>

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: <lang ruby>new = t + 12.hours new = t.in(12.hours) new = t.advance(:hours => 12)</lang>

DateTime class

<lang Ruby>require "date"

puts d1 = DateTime.parse("March 7 2009 7:30pm EST")

  1. 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')</lang>

Output:
2009-03-07T19:30:00-05:00
2009-03-08T07:30:00-05:00
2009-03-08T21:30:00+09:00

Run BASIC

<lang runbasic>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$</lang>

03/08/2009 7:30am

Scala

<lang scala>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))
 }

}</lang>

Output:
March 8 2009 8:30AM EDT
March 8 2009 12:30PM GMT

Seed7

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.

<lang seed7>$ include "seed7_05.s7i";

 include "time.s7i";
 include "duration.s7i";

const func time: parseDate (in string: dateStri) is func

 result
   var time: aTime 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, ' ');
   aTime.year := integer parse (dateParts[3]);
   aTime.month := 1;
   while monthNames[aTime.month] <> dateParts[1] do
     incr(aTime.month);
   end while;
   aTime.day := integer parse (dateParts[2]);
   timeStri := dateParts[4];
   if endsWith(timeStri, "am") then
     aTime.hour := integer parse (timeStri[.. pred(pos(timeStri, ':'))]);
   elsif endsWith(timeStri, "pm") then
     aTime.hour := integer parse (timeStri[.. pred(pos(timeStri, ':'))]) + 12;
   else
     raise RANGE_ERROR;
   end if;
   aTime.minute := integer parse (timeStri[succ(pos(timeStri, ':')) .. length(timeStri) - 2]);
   if dateParts[5] <> "UTC" then
     aTime.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;</lang>
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

SenseTalk

<lang sensetalk>set date to "March 7 2009 7:30pm EST" insert "[month name] [day] [year] [hour12]:[min][pm] [timeZoneID]" into the timeInputFormat

put date + 12 hours </lang> Output: <lang sensetalk>March 8 2009 7:30AM EST</lang>

Sidef

Translation of: Perl

<lang ruby>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')</lang>
Output:
March 8 2009 6:30AM MDT

Smalltalk

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)

<lang smalltalk>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 ]

].</lang>

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

<lang smalltalk>|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.</lang>

Output:

(note that EST should be EDT)

March 8 2009 8:30AM EST
 2009-03-08T13:30:00+00:00

SQL

Works with: Oracle

<lang sql> -- March 7 2009 7:30pm EST

select TO_TIMESTAMP_TZ( 'March 7 2009 7:30pm EST', 'MONTH DD YYYY HH:MIAM TZR' ) at time zone 'US/Eastern' orig_dt_time from dual;

-- 12 hours later DST change

select (TO_TIMESTAMP_TZ( 'March 7 2009 7:30pm EST', 'MONTH DD YYYY HH:MIAM TZR' )+ INTERVAL '12' HOUR) at time zone 'US/Eastern' plus_12_dst from dual;

-- 12 hours later no DST change -- Arizona time, always MST

select (TO_TIMESTAMP_TZ( 'March 7 2009 7:30pm EST', 'MONTH DD YYYY HH:MIAM TZR' )+ INTERVAL '12' HOUR) at time zone 'US/Arizona' plus_12_nodst from dual; </lang>

SQL> SQL> SQL> SQL> SQL>   2    3    4    5    6    7
ORIG_DT_TIME
---------------------------------------------------------------------------
07-MAR-09 07.30.00.000000000 PM US/EASTERN

SQL> SQL> SQL> SQL>   2    3    4    5    6    7    8
PLUS_12_DST
---------------------------------------------------------------------------
08-MAR-09 08.30.00.000000000 AM US/EASTERN

SQL> SQL> SQL> SQL> SQL>   2    3    4    5    6    7    8
PLUS_12_NODST
---------------------------------------------------------------------------
08-MAR-09 05.30.00.000000000 AM US/ARIZONA

Tcl

Works with: Tcl version 8.5

<lang tcl>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</lang>

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

UNIX Shell

requires GNU date <lang bash>epoch=$(date -d 'March 7 2009 7:30pm EST +12 hours' +%s) date -d @$epoch TZ=Asia/Shanghai date -d @$epoch</lang>

Output:
Sun Mar  8 08:30:00 EDT 2009
Sun Mar  8 20:30:00 CST 2009

zkl

The iso8601 library offers additional Time/Date support but using the built in stuff: <lang zkl>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));

}</lang> <lang zkl>add12h("March 7 2009 7:30pm EST").println();</lang>

Output:
March 8 2009 07:30AM