Date format

From Rosetta Code
Task
Date format
You are encouraged to solve this task according to the task description, using any language you may know.
This task has been clarified. Its programming examples are in need of review to ensure that they still fit the requirements of the task.


Task

Display the   current date   in the formats of:

  •   2007-11-23     and
  •   Friday, November 23, 2007



11l

print(Time().format(‘YYYY-MM-DD’))
print(Time().strftime(‘%A, %B %e, %Y’))

68000 Assembly

Works with: NEOGEO MVS

This code only works on the arcade system, not the home consoles, because only the arcade system has a built-in system clock. which can be read using JSR $C0045C. MAME uses your computer's date and time as the source for this data. The code below runs in-line and uses a few macros and labels, but they are mostly self-explanatory. The code required to set up the palettes and print characters to the screen has been omitted for brevity, but is fully implemented.


        JSR SYS_READ_CALENDAR ;outputs calendar date to BIOS RAM

	MOVE.B #'2',D0                  ;a character in single or double quotes refers to its ascii equivalent.
	JSR PrintChar
	MOVE.B #'0',D0
	JSR PrintChar
	
	LEA BIOS_YEAR,A1	
	MOVE.B (A1)+,D0			;stores last 2 digits of year into D0, in binary coded decimal
	JSR UnpackNibbles8		;separate the digits into high and low nibbles: D0 = 00020001
	ADD.L #$00300030,D0		;convert both numerals to their ascii equivalents.
	SWAP D0				;print the "2" first
	JSR PrintChar
	SWAP D0				;then the "1"
	JSR PrintChar
	
	MOVE.B #'-',D0
	JSR PrintChar
	
	MOVE.B (A1)+,D0			;get the month
	JSR UnpackNibbles8		
	ADD.L #$00300030,D0
	SWAP D0
	JSR PrintChar
	SWAP D0
	JSR PrintChar
	
	MOVE.B #'-',D0
	JSR PrintChar
	
	MOVE.B (A1)+,D0			;get the day
	JSR UnpackNibbles8
	ADD.L #$00300030,D0
	SWAP D0
	JSR PrintChar
	SWAP D0
	JSR PrintChar
	
	;now the date is printed.
	
	;Now do it again only written out:
	jsr NewLine
	
	CLR.L D0				;reset D0
	MOVE.B (A1),D0			;A1 happens to point to the weekday
	LSL.W #2,D0				;we are indexing into a table of longs
	LEA Days_Lookup,A2
	LEA (A2,D0),A2
	MOVEA.L (A2),A3			;dereference the pointer into A3, which the PrintString routine takes as an argument.
	
	JSR PrintString
	
	CLR.L D0
	LEA BIOS_MONTH,A1		;GET THE MONTH
	MOVE.B (A1)+,D0
	LSL.W #2,D0
	LEA Months_Lookup,A2
	LEA (A2,D0),A2
	MOVEA.L (A2),A3
	
	JSR PrintString
	
	MOVE.B (A1),D0			;GET THE DAY
	JSR UnpackNibbles8		
	ADD.L #$00300030,D0
	SWAP D0
	JSR PrintChar
	SWAP D0
	JSR PrintChar
	
	MOVE.B #',',D0
	JSR PrintChar
	MOVE.B #' ',D0
	JSR PrintChar
	
	MOVE.B #'2',D0
	JSR PrintChar
	MOVE.B #'0',D0
	JSR PrintChar
	
	LEA BIOS_YEAR,A1	
	MOVE.B (A1)+,D0			;stores last 2 digits of year into D0, in binary coded decimal
	JSR UnpackNibbles8		;separate the digits into high and low nibbles: D0 = 00020001
	ADD.L #$00300030,D0		;convert both numerals to their ascii equivalents.
	SWAP D0					;print the "2" first
	JSR PrintChar
	SWAP D0					;then the "1"
	JSR PrintChar

forever:
	bra forever                              ;trap the program counter

UnpackNibbles8:
; INPUT: D0 = THE VALUE YOU WISH TO UNPACK.
; HIGH NIBBLE IN HIGH WORD OF D0, LOW NIBBLE IN LOW WORD. SWAP D0 TO GET THE OTHER HALF.
	pushWord D1
		CLR.W D1		
		MOVE.B D0,D1
		CLR.L D0
		MOVE.B D1,D0	 ;now D0 = D1 = $000000II, where I = input
		
		AND.B #$F0,D0	 ;chop off bottom nibble
		LSR.B #4,D0		 ;downshift top nibble into bottom nibble of the word
		SWAP D0			 ;store in high word
		AND.B #$0F,D1	 ;chop off bottom nibble
		MOVE.B D1,D0	 ;store in low word
	popWord D1
	rts

Output can be seen here, but is also reproduced below:

2021-09-19
 Sunday, September 19, 2021

8th

d:new 
"%Y-%M-%D" over d:format . cr
"%W, %N %D, %Y" over d:format . cr
bye

AArch64 Assembly

Works with: as version Raspberry Pi 3B version Buster 64 bits
/* ARM assembly AARCH64 Raspberry PI 3B */
/*  program dateFormat64.s   */
 

/*******************************************/
/* Constantes file                         */
/*******************************************/
/* for this file see task include a file in language AArch64 assembly*/
.include "../includeConstantesARM64.inc"
 
.equ GETTIME,   169     // call system linux gettimeofday
 
/*******************************************/
/* Structures                               */
/********************************************/
/* example structure  time  */
    .struct  0
timeval_sec:                     //
    .struct  timeval_sec + 8 
timeval_usec:                     //
    .struct  timeval_usec + 8
timeval_end:
    .struct  0
timezone_min:                     //
    .struct  timezone_min + 8
timezone_dsttime:                 // 
    .struct  timezone_dsttime + 8
timezone_end:
 
/*********************************/
/* Initialized data              */
/*********************************/
.data
szMessError:       .asciz "Error detected !!!!. \n"
szMessResult:      .asciz "Date : @/@/@ \n"        // message result
szMessResult1:     .asciz "Date day : @ @ @ @ \n"  // message result
szJan:             .asciz "Janvier"
szFev:             .asciz "Fèvrier"
szMars:            .asciz "Mars"
szAvril:           .asciz "Avril"
szMai:             .asciz "Mai"
szJuin:            .asciz "Juin"
szJuil:            .asciz "Juillet"
szAout:            .asciz "Aout"
szSept:            .asciz "Septembre"
szOct:             .asciz "Octobre"
szNov:             .asciz "Novembre"
szDec:             .asciz "Décembre"
szLundi:           .asciz "Lundi"
szMardi:           .asciz "Mardi"
szMercredi:        .asciz "Mercredi"
szJeudi:           .asciz "Jeudi"
szVendredi:        .asciz "Vendredi"
szSamedi:          .asciz "Samedi"
szDimanche:        .asciz "Dimanche"
szCarriageReturn:  .asciz "\n"
.align 4
tbDayMonthYear:    .quad  0,  31,  60,  91, 121, 152, 182, 213, 244, 274, 305, 335
                   .quad 366, 397, 425, 456, 486, 517, 547, 578, 609, 639, 670, 700
                   .quad 731, 762, 790, 821, 851, 882, 912, 943, 974,1004,1035,1065
                   .quad 1096,1127,1155,1186,1216,1247,1277,1308,1339,1369,1400,1430
tbMonthName:       .quad szJan
                   .quad szFev
                   .quad szMars
                   .quad szAvril
                   .quad szMai
                   .quad szJuin
                   .quad szJuil
                   .quad szAout
                   .quad szSept
                   .quad szOct
                   .quad szNov
                   .quad szDec
tbDayName:         .quad szLundi
                   .quad szMardi
                   .quad szMercredi
                   .quad szJeudi
                   .quad szVendredi
                   .quad szSamedi
                   .quad szDimanche
 
/*********************************/
/* UnInitialized data            */
/*********************************/
.bss 
.align 4
stTVal:                .skip timeval_end
stTZone:               .skip timezone_end
sZoneConv:             .skip 24
/*********************************/
/*  code section                 */
/*********************************/
.text
.global main 
main:                              // entry of program 
    ldr x0,qAdrstTVal
    ldr x1,qAdrstTZone
    mov x8,#GETTIME
    svc 0
    cmp x0,#-1                     // error ?
    beq 99f
    ldr x1,qAdrstTVal
    ldr x0,[x1,#timeval_sec]       // timestamp in second
    bl dateFormatNum
    ldr x0,[x1,#timeval_sec]       // timestamp in second
    bl dateFormatAlpha
    ldr x0,qTStest1
    bl dateFormatNum
    ldr x0,qTStest1
    bl dateFormatAlpha
    ldr x0,qTStest2
    bl dateFormatNum
    ldr x0,qTStest2
    bl dateFormatAlpha
    ldr x0,qTStest3
    bl dateFormatNum
    ldr x0,qTStest3
    bl dateFormatAlpha
    b 100f
99:
    ldr x0,qAdrszMessError
    bl affichageMess 
100:                               // standard end of the program 
    mov x0,#0                      // return code
    mov x8,#EXIT                   // request to exit program
    svc 0                          // perform the system call
 
qAdrszMessError:          .quad szMessError
qAdrstTVal:               .quad stTVal
qAdrstTZone:              .quad stTZone
qAdrszCarriageReturn:     .quad szCarriageReturn
qAdrsZoneConv:            .quad sZoneConv
qTStest1:                 .quad 1609508339    // 01/01/2021
qTStest2:                 .quad 1657805939    // 14/07/2022
qTStest3:                 .quad 1767221999    // 31/12/2025
/******************************************************************/
/*     date format numeric                                        */ 
/******************************************************************/
/* x0 contains the  timestamp in seconds */
dateFormatNum:
    stp x1,lr,[sp,-16]!            // save  registers
    ldr x2,qSecJan2020
    sub x0,x0,x2                   // total secondes to 01/01/2020
    mov x1,60
    udiv x0,x0,x1                  // divide secondes
    udiv x0,x0,x1                  // divide minutes
    mov x1,#24
    udiv x0,x0,x1                  // divide hours
    mov x11,x0
    mov x1,#(365 * 4 + 1)
    udiv x9,x0,x1
    lsl x9,x9,#2                   // multiply by 4 = year1
    mov x1,#(365 * 4 + 1)
    udiv x2,x11,x1
    msub x10,x2,x1,x11
 
    ldr x1,qAdrtbDayMonthYear
    mov x2,#3
    mov x3,#12
1:
    mul x11,x3,x2
    ldr x4,[x1,x11,lsl 3]         // load days by year
    cmp x10,x4
    bge 2f
    sub x2,x2,1
    cbnz x2,1b
2:                                // x2 = year2
    mov x5,11
    mul x11,x3,x2
    lsl x11,x11,3
    add x11,x11,x1                // table address 
3:
    ldr x4,[x11,x5,lsl 3]         // load days by month
    cmp x10,x4
    bge 4f
    subs x5,x5,1
    bne 3b
4:                                 // x5 = month - 1
    mul x11,x3,x2
    add x11,x11,x5
    ldr x1,qAdrtbDayMonthYear
    ldr x3,[x1,x11,lsl 3]
    sub x0,x10,x3
    add x0,x0,1                    // final compute day
    ldr x1,qAdrsZoneConv
    bl conversion10                // this function do not zero final
    ldr x0,qAdrszMessResult
    ldr x1,qAdrsZoneConv
    bl strInsertAtCharInc          // insert result at first // character
    mov x3,x0
    add x0,x5,1                    // final compute month
    cmp x0,12
    sub x1,x0,12
    csel x0,x1,x0,gt
    ldr x1,qAdrsZoneConv
    bl conversion10
    mov x0,x3
    ldr x1,qAdrsZoneConv
    bl strInsertAtCharInc          // insert result at next // character
    mov x3,x0
    ldr x11,qYearStart
    add x0,x9,x11
    add x0,x0,x2                   // final compute year = 2020 + yeax1 + yeax2
    ldr x1,qAdrsZoneConv
    bl conversion10
    mov x0,x3
    ldr x1,qAdrsZoneConv
    bl strInsertAtCharInc          // insert result at next // character
    bl affichageMess 
100:
    ldp x1,lr,[sp],16              // restaur  2 registers
    ret                            // return to address lr x30
qAdrszMessResult:         .quad szMessResult
/******************************************************************/
/*     date format alphanumeric                                   */ 
/******************************************************************/
/* x0 contains the  timestamp in seconds */
dateFormatAlpha:
    stp x1,lr,[sp,-16]!            // save  registers
    ldr x2,qSecJan2020
    sub x0,x0,x2                   // total secondes to 01/01/2020
    mov x6,x0
    mov x1,60
    udiv x0,x0,x1
    udiv x0,x0,x1
    mov x1,24
    udiv x0,x0,x1
    mov x7,x0
    mov x1,(365 * 4 + 1)
    udiv x9,x0,x1
    lsl x9,x9,#2                   // multiply by 4 = year1
    mov x1,(365 * 4 + 1)
    udiv x0,x7,x1
    msub x10,x0,x1,x7
    ldr x1,qAdrtbDayMonthYear
    mov x8,3
    mov x3,12
1:
    mul x7,x3,x8
    ldr x4,[x1,x7,lsl 3]          // load days by year
    cmp x10,x4
    bge 2f
    sub x8,x8,1
    cmp x8,0
    bne 1b
2:                                 // x8 = yeax2
    mov x5,#11
    mul x7,x3,x8
    lsl x7,x7,3
    add x7,x7,x1
3:
    ldr x4,[x7,x5,lsl 3]          // load days by month
    cmp x10,x4
    bge 4f
    subs x5,x5,1
    bne 3b
4:                                 // x5 = month - 1
 
    mov x0,x6                      // number secondes depuis 01/01/2020
    ldr x1,qNbSecByDay
    udiv x0,x6,x1
    mov x1,7
    udiv x2,x0,x1
    msub x3,x2,x1,x0
    add x2,x3,2
    cmp x2,7
    sub x3,x2,7
    csel x2,x3,x2,ge
    ldr x1,qAdrtbDayName
    ldr x1,[x1,x2,lsl 3]
    ldr x0,qAdrszMessResult1

    bl strInsertAtCharInc          // insert result at next // character
    mov x3,x0
    mov x7,12
    mul x11,x7,x8
    add x11,x11,x5
    ldr x1,qAdrtbDayMonthYear
    ldr x7,[x1,x11,lsl 3]
    sub x0,x10,x7
    add x0,x0,1                   // final compute day
    ldr x1,qAdrsZoneConv
    bl conversion10                // this function do not zero final
    mov x0,x3
    ldr x1,qAdrsZoneConv
    bl strInsertAtCharInc          // insert result at first // character
    mov x3,x0
    ldr x1,qAdrtbMonthName
    cmp x5,12
    sub x2,x5,12
    csel x5,x2,x5,ge
    ldr x1,[x1,x5,lsl 3]          // month name
    mov x0,x3
    bl strInsertAtCharInc          // insert result at first // character
    mov x3,x0
    ldr x0,qYearStart
    add x0,x0,x8
    add x0,x0,x9                      // final compute year = 2020 + yeax1 + yeax2
 
    ldr x1,qAdrsZoneConv
    bl conversion10                // this function do not zero final
    mov x0,x3
    ldr x1,qAdrsZoneConv
    bl strInsertAtCharInc          // insert result at first // character
    bl affichageMess 
100:
    ldp x1,lr,[sp],16              // restaur  2 registers
    ret                            // return to address lr x30
qAdrszMessResult1:         .quad szMessResult1
qSecJan2020:              .quad 1577836800
qAdrtbDayMonthYear:       .quad tbDayMonthYear
qYearStart:               .quad 2020
qAdrtbMonthName:          .quad tbMonthName
qAdrtbDayName:            .quad tbDayName
qNbSecByDay:              .quad 3600 * 24
/********************************************************/
/*        File Include fonctions                        */
/********************************************************/
/* for this file see task include a file in language AArch64 assembly */
.include "../includeARM64.inc"

ABAP

report zdate.
data: lv_month type string,
      lv_weekday type string,
      lv_date type string,
      lv_day type c.

call function 'DATE_COMPUTE_DAY'
  exporting date = sy-datum
  importing day  = lv_day.
select single ltx from t247 into lv_month
  where spras = sy-langu and
  mnr = sy-datum+4(2).

select single langt from t246 into lv_weekday
  where sprsl = sy-langu and
  wotnr = lv_day.

concatenate lv_weekday ', ' lv_month ' ' sy-datum+6(2) ', ' sy-datum(4) into lv_date respecting blanks.
write lv_date.
concatenate sy-datum(4) '-' sy-datum+4(2) '-' sy-datum+6(2) into lv_date.
write / lv_date.

Action!

DEFINE PTR="CARD"

TYPE Date=[
  INT year
  BYTE month
  BYTE day]

PTR ARRAY DayOfWeeks(7)
PTR ARRAY Months(12)

PROC Init()
  DayOfWeeks(0)="Sunday"   DayOfWeeks(1)="Monday"
  DayOfWeeks(2)="Tuesday"  DayOfWeeks(3)="Wednesday"
  DayOfWeeks(4)="Thursday" DayOfWeeks(5)="Friday"
  DayOfWeeks(6)="Saturday"
  Months(0)="January"   Months(1)="February"
  Months(2)="March"     Months(3)="April"
  Months(4)="May"       Months(5)="June"
  Months(6)="July"      Months(7)="August"
  Months(8)="September" Months(9)="October"
  Months(10)="November" Months(11)="December"
RETURN

;https://en.wikipedia.org/wiki/Determination_of_the_day_of_the_week#Sakamoto.27s_methods
BYTE FUNC DayOfWeek(Date POINTER d)	;1<=m<=12, y>1752
  BYTE ARRAY t=[0 3 2 5 0 3 5 1 4 6 2 4]
  BYTE res
  INT y

  y=d.year
  IF d.month<3 THEN
    y==-1
  FI
  res=(y+y/4-y/100+y/400+t(d.month-1)+d.day) MOD 7
RETURN (res)

PROC PrintB2(BYTE x)
  IF x<10 THEN
    Put('0)
  FI
  PrintB(x)
RETURN

PROC PrintDateShort(Date POINTER d)
  PrintI(d.year) Put('-)
  PrintB2(d.month) Put('-)
  PrintB2(d.day)
RETURN

PROC PrintDateLong(Date POINTER d)
  BYTE wd

  wd=DayOfWeek(d)
  Print(DayOfWeeks(wd)) Print(", ")
  Print(Months(d.month-1)) Put(' )
  PrintB(d.day) Print(", ")
  PrintI(d.year)
RETURN

PROC Main()
  Date d

  Init()

  ;There is no function to get the current date
  ;on Atari 8-bit computer
  d.year=2021 d.month=9 d.day=1

  PrintDateShort(d) PutE()
  PrintDateLong(d) PutE()
RETURN
Output:

Screenshot from Atari 8-bit computer

2021-09-01
Wednesday, September 1, 2021

Ada

with Ada.Calendar;             use Ada.Calendar;
with Ada.Calendar.Formatting;  use Ada.Calendar.Formatting;
with Ada.Text_IO;              use Ada.Text_IO;

procedure Date_Format is
   function Image (Month : Month_Number) return String is
   begin
      case Month is
         when 1  => return "January";
         when 2  => return "February";
         when 3  => return "March";
         when 4  => return "April";
         when 5  => return "May";
         when 6  => return "June";
         when 7  => return "July";
         when 8  => return "August";
         when 9  => return "September";
         when 10 => return "October";
         when 11 => return "November";
         when 12 => return "December";
      end case;
   end Image;
   function Image (Day : Day_Name) return String is
   begin
      case Day is
         when Monday    => return "Monday";
         when Tuesday   => return "Tuesday";
         when Wednesday => return "Wednesday";
         when Thursday  => return "Thursday";
         when Friday    => return "Friday";
         when Saturday  => return "Saturday";
         when Sunday    => return "Sunday";
      end case;
   end Image;
   Today : Time := Clock;
begin
   Put_Line (Image (Today) (1..10));
   Put_Line
   (  Image (Day_Of_Week (Today)) & ", "
   &  Image (Ada.Calendar.Month (Today))
   &  Day_Number'Image (Ada.Calendar.Day (Today)) & ","
   &  Year_Number'Image (Ada.Calendar.Year (Today))
   );
end Date_Format;
Output:
2008-10-03
Friday, October 3, 2008

ALGOL 68

Works with: ALGOL 68 version Standard - using the a68g standard library
Works with: ALGOL 68G version Any - tested with release mk15-0.8b.fc9.i386

Note: the format can be used for both printing and reading date data.

# define the layout of the date/time as provided by the call to local time #
STRUCT ( INT sec, min, hour, mday, mon, year, wday, yday, isdst) tm = (6,5,4,3,2,1,7,~,8);

FORMAT # some useful format declarations #
  ymd repr = $4d,"-"2d,"-"2d$,
  month repr =    $c("January","February","March","April","May","June","July",
                     "August","September","October","November","December")$,
  week day repr = $c("Sunday","Monday","Tuesday","Wednesday",
                     "Thursday","Friday","Saturday")$,
  dmdy repr =     $f(week day repr)", "f(month repr)" "g(-0)", "g(-4)$,

  mon  = $c("Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec")$,
  wday = $c("Sun","Mon","Tue","Wed","Thu","Fri","Sat")$,
  tz   = $c("MSK","MSD")$,
  unix time repr = $f(wday)" "f(mon)z-d," "dd,":"dd,":"dd," "f(tz)" "dddd$;

[]INT now = local time;

printf((ymd repr,       now[year OF tm:mday OF tm], $l$));
printf((dmdy repr,      now[wday OF tm], now[mon OF tm], now[mday OF tm], now[year OF tm], $l$));

printf((unix time repr, now[wday OF tm], now[mon OF tm], now[mday OF tm], 
                        now[hour OF tm:sec OF tm], now[isdst OF tm]+1, now[year OF tm], $l$))
Output:
2009-04-08
Wednesday, April 8, 2009
Wed Apr  8 18:04:02 MSD 2009

Apex

Datetime dtNow = datetime.now();
String strDt1 = dtNow.format('yyyy-MM-dd');
String strDt2 = dtNow.format('EEEE, MMMM dd, yyyy');
system.debug(strDt1); // "2007-11-10"
system.debug(strDt2); //"Sunday, November 10, 2007"
Output:
2016-04-20
Wednesday, April 20, 2016

AppleScript

Idiomatic

This restores the legitimate code which has twice now been deleted by the poster of the hacks below. Explicitly: square brackets are not and have never been part of the AppleScript language and «class isot» as string is a hack someone discovered many years ago when it wasn't possible to coerce AppleScript month enums directly to integer and when AppleScript's string class used 8-bit characters. Back then, the coercion from string to «class isot» also worked. But this ended with the introduction of AppleScript 2.0 in 2007, when string, Unicode text, and text became synonymous terms for UTF-16 text. The ability to coerce from 8-bit text specifically to string was retained for compatibility with existing scripts and for reading non-Unicode text files. Other classes of text such C string were discontinued.

Whether or not they happen to work, to insist on posting code containing things which have never been part of the language without noting them as hacks, when they're entirely unnecessary, and deleting legitimate and effective code to make way for them, is seriously to misinform readers.

set {year:y, month:m, day:d, weekday:w} to (current date)

tell (y * 10000 + m * 100 + d) as text to set shortFormat to text 1 thru 4 & "-" & text 5 thru 6 & "-" & text 7 thru 8
set longFormat to (w as text) & (", " & m) & (space & d) & (", " & y)

return (shortFormat & linefeed & longFormat)
Output:
"2020-10-28
Wednesday, October 28, 2020"

Hack alternative

AppleScript date objects are very simple to manipulate, provided one is familiar with the slightly unintuitive nature of how they should be handled in order to be robust and produce the desired result across all systems. Despite the official documentation claiming otherwise, AppleScript is not able to parse date strings that don’t strictly adhere to the date and time format strings specified in System Preferences—thus it is a setting that is specific to one’s system, and won’t naturally port.

AppleScript provides properties and classes specifically for manipulating or constructing date objects that are not dependent on anything outwith the AppleScript language. In most cases, the current date command provides a starting point, from which one gets current or sets new values for its day, month, year, and time properties and property classes to determine or affect the date a particular date object refers to.

Formatting is usually achieved by extracting individual date components, performing text manipulations (e.g. to prepend leading zeroes) on each of these, then concatenating these for the final result. The «class isot» class doesn’t have a vernacular form and can only be accessed using its raw chevron syntactic form, which others may recognise from similar AppleScript classes such as «class furl», «class utf8» and so forth. They can provide some useful—and, often, more reliable—features that can save the headache suffered by many when learning how the file, POSIX file, and alias classes differ between one another, and then also with the way the same class can be implemented in ways or yield unexpected results when used in a context specific to a scriptable application.

«class isot» and date class objects can coerce to and from one another. The «class isot» is an opaque data type wrapping the hexbytes of an ISO-8601 formatted datetime string. Sadly, it doesn’t permit one to use it to convert a string into hexbytes, but it is ideal for taking a date reference via the «class isot» intermediary form and coercing this to string class (whose chevron syntax form is «class TEXT»), but it will not coerce onto other AppleScript classes that are normally used interchangeably to represent strings, namely text («class ctxt») or unicode text («class utxt»).

Both scripts provided below, contributed separately by different users, each make use of the features discussed above. The first demonstrates the simplest and most direct solution, but simplicity forces specificity, which limits what other algorithmic problems it could usefully or easily be adapted to solve. The latter borrows a functional approach and favours an initial investment to create the atomic handlers that pay off by providing the reusable building blocks of identical code that will be the composable functions all other scripts are assembled from sparing much of the need to write new code to solve the vast majority of problems on this site. Generality, versatility and adaptability of this approach can be proven mathematically.


tell (the current date)
	set shortdate to text 1 thru 10 of (it as «class isot» as string)
	set longdate to the contents of [its weekday, ", ", ¬
		(its month), " ", day, ", ", year] as text
end tell

log the shortdate
log the longdate
Output:
2020-09-11
Friday, September 11, 2020

Functional

Or, emphasising productivity and functional composition:

-- iso8601Short :: Date -> String
on iso8601Short(dte)
    text 1 thru 10 of iso8601Local(dte)
end iso8601Short


-- longDate :: Date -> String
on longDate(dte)
    tell dte
        "" & its weekday & ", " & its month & " " & its day & ", " & year
    end tell
end longDate


---------------------------- TEST --------------------------
on run
    
    unlines(apList({iso8601Short, longDate}, ¬
        {current date}))
    
end run


-------------------------- GENERIC -------------------------


-- Each member of a list of functions applied to
-- each of a list of arguments, deriving a list of new values
-- apList (<*>) :: [(a -> b)] -> [a] -> [b]
on apList(fs, xs)
    set lst to {}
    repeat with f in fs
        tell mReturn(contents of f)
            repeat with x in xs
                set end of lst to |λ|(contents of x)
            end repeat
        end tell
    end repeat
    return lst
end apList


-- iso8601Local :: Date -> String
on iso8601Local(dte)
    (dte as «class isot» as string)
end iso8601Local


-- mReturn :: First-class m => (a -> b) -> m (a -> b)
on mReturn(f)
    -- 2nd class handler function lifted into 1st class script wrapper. 
    if script is class of f then
        f
    else
        script
            property |λ| : f
        end script
    end if
end mReturn


-- unlines :: [String] -> String
on unlines(xs)
    -- A single string formed by the intercalation
    -- of a list of strings with the newline character.
    set {dlm, my text item delimiters} to ¬
        {my text item delimiters, linefeed}
    set s to xs as text
    set my text item delimiters to dlm
    s
end unlines
Output:
2020-09-11
Friday, September 11, 2020

ARM Assembly

Works with: as version Raspberry Pi
/* ARM assembly Raspberry PI  */
/*  program dateFormat.s   */

/* REMARK 1 : this program use routines in a include file 
   see task Include a file language arm assembly 
   for the routine affichageMess conversion10 
   see at end of this program the instruction include */

/*******************************************/
/* Constantes                              */
/*******************************************/
.equ STDOUT, 1           @ Linux output console
.equ EXIT,   1           @ Linux syscall
.equ WRITE,  4           @ Linux syscall
.equ BRK,    0x2d        @ Linux syscall
.equ CHARPOS,     '@'

.equ GETTIME,   0x4e     @ call system linux gettimeofday

/*******************************************/
/* Structures                               */
/********************************************/
/* example structure  time  */
    .struct  0
timeval_sec:                     @
    .struct  timeval_sec + 4 
timeval_usec:                     @
    .struct  timeval_usec + 4 
timeval_end:
    .struct  0
timezone_min:                     @
    .struct  timezone_min + 4 
timezone_dsttime:                 @ 
    .struct  timezone_dsttime + 4 
timezone_end:

/*********************************/
/* Initialized data              */
/*********************************/
.data
szMessError:       .asciz "Error detected !!!!. \n"
szMessResult:      .asciz "Date : @/@/@ \n"  @ message result
szMessResult1:     .asciz "Date day : @ @ @ @ \n"  @ message result
szJan:             .asciz "Janvier"
szFev:             .asciz "Février"
szMars:            .asciz "Mars"
szAvril:            .asciz "Avril"
szMai:             .asciz "Mai"
szJuin:            .asciz "Juin"
szJuil:            .asciz "Juillet"
szAout:            .asciz "Aout"
szSept:            .asciz "Septembre"
szOct:             .asciz "Octobre"
szNov:             .asciz "Novembre"
szDec:             .asciz "Décembre"
szLundi:           .asciz "Lundi"
szMardi:           .asciz "Mardi"
szMercredi:        .asciz "Mercredi"
szJeudi:           .asciz "Jeudi"
szVendredi:        .asciz "Vendredi"
szSamedi:          .asciz "Samedi"
szDimanche:        .asciz "Dimanche"
szCarriageReturn:  .asciz "\n"
.align 4
tbDayMonthYear:    .int  0,  31,  60,  91, 121, 152, 182, 213, 244, 274, 305, 335
                   .int 366, 397, 425, 456, 486, 517, 547, 578, 609, 639, 670, 700
                   .int 731, 762, 790, 821, 851, 882, 912, 943, 974,1004,1035,1065
                   .int 1096,1127,1155,1186,1216,1247,1277,1308,1339,1369,1400,1430
tbMonthName:       .int szJan
                   .int szFev
                   .int szMars
                   .int szAvril
                   .int szMai
                   .int szJuin
                   .int szJuil
                   .int szAout
                   .int szSept
                   .int szOct
                   .int szNov
                   .int szDec
tbDayName:         .int szLundi
                   .int szMardi
                   .int szMercredi
                   .int szJeudi
                   .int szVendredi
                   .int szSamedi
                   .int szDimanche

/*********************************/
/* UnInitialized data            */
/*********************************/
.bss 
.align 4
stTVal:                .skip timeval_end
stTZone:               .skip timezone_end
sZoneConv:             .skip 100
/*********************************/
/*  code section                 */
/*********************************/
.text
.global main 
main:                              @ entry of program 
    ldr r0,iAdrstTVal
    ldr r1,iAdrstTZone
    mov r7,#GETTIME
    svc 0
    cmp r0,#-1                     @ error ?
    beq 99f
    ldr r1,iAdrstTVal
    ldr r0,[r1,#timeval_sec]       @ timestemp in second
    bl dateFormatNum
    ldr r0,[r1,#timeval_sec]       @ timestemp in second
    bl dateFormatAlpha
    ldr r0,iTStest1
    bl dateFormatNum
    ldr r0,iTStest1
    bl dateFormatAlpha
    ldr r0,iTStest2
    bl dateFormatNum
    ldr r0,iTStest2
    bl dateFormatAlpha
    ldr r0,iTStest3
    bl dateFormatNum
    ldr r0,iTStest3
    bl dateFormatAlpha
    b 100f
99:
    ldr r0,iAdrszMessError
    bl affichageMess 
100:                               @ standard end of the program 
    mov r0,#0                      @ return code
    mov r7,#EXIT                   @ request to exit program
    svc 0                          @ perform the system call

iAdrszMessError:          .int szMessError
iAdrstTVal:               .int stTVal
iAdrstTZone:              .int stTZone
iAdrszCarriageReturn:     .int szCarriageReturn
iAdrsZoneConv:            .int sZoneConv
iTStest1:                 .int 1609508339    @ 01/01/2021
iTStest2:                 .int 1657805939    @ 14/07/2022
iTStest3:                 .int 1767221999    @ 31/12/2025
/******************************************************************/
/*     date format numeric                                        */ 
/******************************************************************/
/* r0 contains the  timestamp in seconds */
dateFormatNum:
    push {r1-r11,lr}                             @ save  registers 
    ldr r2,iSecJan2020
    sub r0,r0,r2                   @ total secondes to 01/01/2020
    mov r1,#60
    bl division
    mov r0,r2
    mov r6,r3                      @ compute secondes
    mov r1,#60
    bl division
    mov r7,r3                      @ compute minutes
    mov r0,r2
    mov r1,#24
    bl division
    mov r8,r3                      @ compute hours
    mov r0,r2
    mov r11,r0
    mov r1,#(365 * 4 + 1)
    bl division
    lsl r9,r2,#2                   @ multiply by 4 = year1
    mov r1,#(365 * 4 + 1)
    mov r0,r11
    bl division
    mov r10,r3

    ldr r1,iAdrtbDayMonthYear
    mov r2,#3
    mov r3,#12
1:
    mul r11,r3,r2
    ldr r4,[r1,r11,lsl #2]         @ load days by year
    cmp r10,r4
    bge 2f
    sub r2,r2,#1
    cmp r2,#0
    bne 1b
2:                                 @ r2 = year2
    mov r5,#11
    mul r11,r3,r2
    lsl r11,#2
    add r11,r1                     @ table address 
3:
    ldr r4,[r11,r5,lsl #2]         @ load days by month
    cmp r10,r4
    bge 4f
    subs r5,r5,#1
    bne 3b
4:                                 @ r5 = month - 1
    mul r11,r3,r2
    add r11,r5
    ldr r1,iAdrtbDayMonthYear
    ldr r3,[r1,r11,lsl #2]
    sub r0,r10,r3
    add r0,r0,#1                   @ final compute day
    ldr r1,iAdrsZoneConv
    bl conversion10                @ this function do not zero final
    mov r11,#0                     @ store zero final
    strb r11,[r1,r0]
    ldr r0,iAdrszMessResult
    ldr r1,iAdrsZoneConv
    bl strInsertAtCharInc          @ insert result at first @ character
    mov r3,r0
    add r0,r5,#1                   @ final compute month
    cmp r0,#12
    subgt r0,#12
    ldr r1,iAdrsZoneConv
    bl conversion10
    mov r11,#0                      @ store zero final
    strb r11,[r1,r0]
    mov r0,r3
    ldr r1,iAdrsZoneConv
    bl strInsertAtCharInc          @ insert result at next @ character
    mov r3,r0
    ldr r11,iYearStart
    add r0,r9,r11
    add r0,r0,r2                   @ final compute year = 2020 + year1 + year2
    ldr r1,iAdrsZoneConv
    bl conversion10
    mov r11,#0                     @ store zero final
    strb r11,[r1,r0]
    mov r0,r3
    ldr r1,iAdrsZoneConv
    bl strInsertAtCharInc          @ insert result at next @ character
    bl affichageMess 
100:
    pop {r1-r11,lr}                @ restaur registers
    bx lr                          @ return
iAdrszMessResult:         .int szMessResult
/******************************************************************/
/*     date format alphanumeric                                   */ 
/******************************************************************/
/* r0 contains the  timestamp in seconds */
dateFormatAlpha:
    push {r1-r10,lr}               @ save  registers 
    ldr r2,iSecJan2020
    sub r0,r0,r2                   @ total secondes to 01/01/2020
    mov r6,r0
    mov r1,#60
    bl division
    mov r0,r2
    mov r1,#60
    bl division
    mov r0,r2
    mov r1,#24
    bl division
    mov r0,r2
    mov r8,r0
    mov r1,#(365 * 4 + 1)
    bl division
    lsl r9,r2,#2                   @ multiply by 4 = year1
    mov r1,#(365 * 4 + 1)
    mov r0,r8
    bl division
    mov r10,r3                     @ reste

    ldr r1,iAdrtbDayMonthYear
    mov r7,#3
    mov r3,#12
1:
    mul r8,r3,r7
    ldr r4,[r1,r8,lsl #2]          @ load days by year
    cmp r10,r4
    bge 2f
    sub r7,r7,#1
    cmp r7,#0
    bne 1b
2:                                 @ r7 = year2
    mov r5,#11
    mul r8,r3,r7
    lsl r8,#2
    add r8,r1
3:
    ldr r4,[r8,r5,lsl #2]          @ load days by month
    cmp r10,r4
    bge 4f
    subs r5,r5,#1
    bne 3b
4:                                 @ r5 = month - 1

    mov r0,r6                      @ number secondes depuis 01/01/2020
    ldr r1,iNbSecByDay
    bl division
    mov r0,r2
    mov r1,#7
    bl division
    add r2,r3,#2
    cmp r2,#7
    subge r2,#7
    ldr r1,iAdrtbDayName
    ldr r1,[r1,r2,lsl #2]
    ldr r0,iAdrszMessResult1
    bl strInsertAtCharInc          @ insert result at next @ character
    mov r3,r0
    mov r8,#12
    mul r11,r8,r7
    add r11,r5
    ldr r1,iAdrtbDayMonthYear
    ldr r8,[r1,r11,lsl #2]
    sub r0,r10,r8
    add r0,r0,#1                   @ final compute day
    ldr r1,iAdrsZoneConv
    bl conversion10                @ this function do not zero final
    mov r8,#0                      @ store zero final
    strb r8,[r1,r0]
    mov r0,r3
    ldr r1,iAdrsZoneConv
    bl strInsertAtCharInc          @ insert result at first @ character
    mov r3,r0
    ldr r1,iAdrtbMonthName
    cmp r5,#12
    subge r5,#12
    ldr r1,[r1,r5,lsl #2]          @ month name
    mov r0,r3
    bl strInsertAtCharInc          @ insert result at first @ character
    mov r3,r0
    ldr r0,iYearStart
    add r0,r7
    add r0,r9                      @ final compute year = 2020 + year1 + year2

    ldr r1,iAdrsZoneConv
    bl conversion10                @ this function do not zero final
    mov r8,#0                      @ store zero final
    strb r8,[r1,r0]
    mov r0,r3
    ldr r1,iAdrsZoneConv
    bl strInsertAtCharInc          @ insert result at first @ character
    bl affichageMess 
100:
    pop {r1-r10,lr}                @ restaur registers
    bx lr                          @ return
iAdrszMessResult1:         .int szMessResult1
iSecJan2020:              .int 1577836800
iAdrtbDayMonthYear:       .int tbDayMonthYear
iYearStart:               .int 2020
iAdrtbMonthName:          .int tbMonthName
iAdrtbDayName:            .int tbDayName
iNbSecByDay:              .int 3600 * 24
/***************************************************/
/*      ROUTINES INCLUDE                 */
/***************************************************/
.include "../affichage.inc"
Output:
Date : 30/3/2020
Date day : Lundi 30 Mars 2020
Date : 1/1/2021
Date day : Vendredi 1 Janvier 2021
Date : 14/7/2022
Date day : Jeudi 14 Juillet 2022
Date : 31/12/2025
Date day : Mercredi 31 Décembre 2025

Arturo

currentTime: now

print to :string.format: "YYYY-MM-dd" currentTime
print to :string.format: "dddd, MMMM dd, YYYY" currentTime
Output:
2021-03-11
Thursday, March 11, 2021

AutoHotkey

FormatTime, Date1, , yyyy-MM-dd ; "2007-11-10"
FormatTime, Date2, , LongDate   ; "Sunday, November 10, 2007"
MsgBox %Date1% `n %Date2%

AutoIt

This solution uses the locale settings for names of days and months.

#include <Date.au3>

$iYear = 2007
$iMonth = 11
$iDay = 10

ConsoleWrite(StringFormat('%4d-%02d-%02d', $iYear, $iMonth, $iDay) & @LF)

$iWeekDay = _DateToDayOfWeekISO($iYear, $iMonth, $iDay)
ConsoleWrite(StringFormat('%s, %s %02d, %4d', _GetLongDayLocale($iWeekDay), _GetLongMonthLocale($iMonth), $iDay, $iYear) & @LF)


Func _GetLongDayLocale($_iWeekDay)  ; 1..7 Monday=1
	Local $aDayName[8] = [0, 0x2A, 0x2B, 0x2C, 0x2D, 0x2E, 0x2F, 0x30]
	Return GetLocaleInfo($aDayName[$_iWeekDay])
EndFunc

Func _GetLongMonthLocale($_iMonth)  ; 1..12 January=1
	Local $aMonthName[13] = [0, 0x38, 0x39, 0x3A, 0x3B, 0x3C, 0x3D, 0x3E, 0x3F, 0x40, 0x41, 0x42, 0x43]
	Return GetLocaleInfo($aMonthName[$_iMonth])
EndFunc

Func GetLocaleInfo($_LCType)
	Local $ret, $LCID, $sBuffer, $iLen
	$ret = DllCall('kernel32', 'long', 'GetSystemDefaultLCID')
	$LCID = $ret[0]
	$ret = DllCall('kernel32', 'long', 'GetLocaleInfo', 'long', $LCID, 'long', $_LCType, 'str', $sBuffer, 'long', 0)
	$iLen = $ret[0]
	$ret = DllCall('kernel32', 'long', 'GetLocaleInfo', 'long', $LCID, 'long', $_LCType, 'str', $sBuffer, 'long', $iLen)
	Return $ret[3]
EndFunc
Output:
2007-11-10
Samstag, November 10, 2007

--BugFix (talk) 16:24, 17 November 2013 (UTC)

AWK

Works with: Gawk
$ awk 'BEGIN{t=systime();print strftime("%Y-%m-%d",t)"\n"strftime("%A, %B %d, %Y",t)}'
2009-05-15
Friday, May 15, 2009

BaCon

' Date format
n = NOW
PRINT YEAR(n), MONTH(n), DAY(n) FORMAT "%ld-%02ld-%02ld\n"
PRINT WEEKDAY$(n), MONTH$(n), DAY(n), YEAR(n) FORMAT "%s, %s %02ld, %ld\n"
Output:
prompt$ ./date-format
2017-02-17
Friday, February 17, 2017

BASIC

Works with: FreeBASIC
#include "vbcompat.bi"

DIM today As Double = Now()

PRINT Format(today, "yyyy-mm-dd") 
PRINT Format(today, "dddd, mmmm d, yyyy")

Batch File

@echo off
setlocal enabledelayedexpansion

:: Define arrays of days/months we'll need
set daynames=Monday Tuesday Wednesday Thursday Friday Saturday Sunday
set monthnames=January February March April May June July August September October November December

:: Separate the output of the 'date /t' command (outputs in the format of "Sun 16/04/2017") into 4 variables
for /f "tokens=1,2,3,4 delims=/ " %%i in ('date /t') do (
  set dayname=%%i
  set day=%%j
  set month=%%k
  set year=%%l
)

:: Crosscheck the first 3 letters of every word in %daynames% to the 3 letter day name found previously
for %%i in (%daynames%) do (
  set tempdayname=%%i
  set comparedayname=!tempdayname:~0,3!
  if "%dayname%"=="!comparedayname!" set fulldayname=%%i
)

:: Variables starting with "0" during the 'set /a' command are treated as octal numbers. To avoid this, if the first character of %month% is "0", it is removed
if "%month:~0,1%"=="0" set monthtemp=%month:~1,1%
set monthcount=0

:: Iterates through %monthnames% and when it reaches the amount of iterations dictated by %month%, sets %monthname% as the current month being iterated through
for %%i in (%monthnames%) do (
  set /a monthcount+=1
  if %monthtemp%==!monthcount! set monthname=%%i
)

echo %year%-%month%-%day%
echo %fulldayname%, %monthname% %day%, %year%
pause>nul
Output:
2017-04-16
Sunday,  16, 2017

BBC BASIC

      daysow$ = "Sunday    Monday    Tuesday   Wednesday Thursday  Friday    Saturday"
      months$ = "January   February  March     April     May       June      " + \
      \         "July      August    September October   November  December"
      
      date$ = TIME$
      dayow% = (INSTR(daysow$, MID$(date$,1,3)) + 9) DIV 10
      month% = (INSTR(months$, MID$(date$,8,3)) + 9) DIV 10
      
      PRINT MID$(date$,12,4) "-" RIGHT$("0"+STR$month%,2) + "-" + MID$(date$,5,2)
      
      PRINT FNrtrim(MID$(daysow$, dayow%*10-9, 10)) ", " ;
      PRINT FNrtrim(MID$(months$, month%*10-9, 10)) " " ;
      PRINT MID$(date$,5,2) ", " MID$(date$,12,4)
      END
      
      DEF FNrtrim(A$)
      WHILE RIGHT$(A$) = " " A$ = LEFT$(A$) : ENDWHILE
      = A$

Beads

//  time_to_str(format, time, city, lang)
//  format directives:
//    [sun]       - abbreviated weekday, e.g. Sun
//    [sunday]    - full weekday name, e.g. Sunday
//    [jan]       - abbrev month
//    [january]   - full month
//    [day]       - day of the month 1, 2, ..31
//    [day2]      - day of the month as two digits 01, 02, ..31
//    [hour]      - hour 00, 01, 03..23
//    [hour12]    - hour 1..12
//    [julian]    - day of the year 1..366
//    [month]     - month 1..12
//    [month2]    - month as two digits 01, 02, ..12
//    [minute]    - Minute 00, 01, 02..59
//    [am]        - AM or PM 
//    [sec]       - second 00, 01, 02..61
//    [msec]      - millisecond 000...999
//    [week sun]  - week number of the year, sunday based (ranges 01-53, per ISO spec)
//    [week mon]  - week number of the year, monday based
//    [year]      - year with century 2024
//    [year2]     - year without century 00, 01, ..99
//    [date]      - default date format (e.g. Jan 14, 2015  )
//    [date time] -  (e.g. Jan 14, 2015 3:45 PM)
//    [iso date]  = [year]-[month2]-[day2], e.g. 2015-02-22 
//    [iso time]  = [hour]:[minute]:[second], e.g. 18:06:05
beads 1 program 'Date format'

calc main_init
	log time_to_str('[iso date]')
	log time_to_str('[sunday], [january] [day2], [year]')
Output:
2021-03-11
Thursday, March 11, 2021

C

#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#define MAX_BUF 50

int main(void)
{
  char buf[MAX_BUF];
  time_t seconds = time(NULL);
  struct tm *now = localtime(&seconds);
  const char *months[] = {"January", "February", "March", "April", "May", "June",
                          "July", "August", "September", "October", "November", "December"};

  const char *days[] = {"Sunday", "Monday", "Tuesday", "Wednesday","Thursday","Friday","Saturday"};

  (void) printf("%d-%d-%d\n", now->tm_year + 1900, now->tm_mon + 1, now->tm_mday);
  (void) printf("%s, %s %d, %d\n",days[now->tm_wday], months[now->tm_mon],
               now->tm_mday, now->tm_year + 1900);
  /* using the strftime (the result depends on the locale) */
  (void) strftime(buf, MAX_BUF, "%A, %B %e, %Y", now);
  (void) printf("%s\n", buf);
  return EXIT_SUCCESS;
}
Output:
2009-5-13
Wednesday, May 13, 2009
Wednesday, May 13, 2009

C#

using System;

namespace RosettaCode.DateFormat
{
    class Program
    {
        static void Main(string[] args)
        {
            DateTime today = DateTime.Now.Date;
            Console.WriteLine(today.ToString("yyyy-MM-dd"));
            Console.WriteLine(today.ToString("dddd, MMMMM d, yyyy"));
        }
    }
}

C++

// Display the current date in the formats of "2007-11-10"
// and "Sunday, November 10, 2007". 

#include <vector>
#include <string>
#include <iostream>
#include <ctime>

/** Return the current date in a string, formatted as either ISO-8601
 *  or "Weekday-name, Month-name Day, Year".
 *
 *  The date is initialized when the object is created and will return
 *  the same date for the lifetime of the object.  The date returned
 *  is the date in the local timezone.
 */
class Date
{
    struct tm ltime;

public:
    /// Default constructor.
    Date()
    {
        time_t t = time(0);
        localtime_r(&t, &ltime);
    }
    
    /** Return the date based on a format string.  The format string is
     *  fed directly into strftime().  See the strftime() documentation
     *  for information on the proper construction of format strings.
     *
     *  @param[in] fmt is a valid strftime() format string.
     *
     *  @return a string containing the formatted date, or a blank string
     *      if the format string was invalid or resulted in a string that
     *      exceeded the internal buffer length.
     */
    std::string getDate(const char* fmt)
    {
        char out[200];
        size_t result = strftime(out, sizeof out, fmt, &ltime);
        return std::string(out, out + result);
    }
    
    /** Return the date in ISO-8601 date format.
     *
     *  @return a string containing the date in ISO-8601 date format.
     */
    std::string getISODate() {return getDate("%F");}
    
    /** Return the date formatted as "Weekday-name, Month-name Day, Year".
     *
     *  @return a string containing the date in the specified format.
     */
    std::string getTextDate() {return getDate("%A, %B %d, %Y");}
};

int main()
{
    Date d;
    std::cout << d.getISODate() << std::endl;
    std::cout << d.getTextDate() << std::endl;
    return 0;
}
Output:
2009-05-14
Thursday, May 14, 2009

Clojure

(let [now (.getTime (java.util.Calendar/getInstance))
      f1  (java.text.SimpleDateFormat. "yyyy-MM-dd")
      f2  (java.text.SimpleDateFormat. "EEEE, MMMM dd, yyyy")]
  (println (.format f1 now))
  (println (.format f2 now)))
Output:
2009-12-06
Sunday, December 06, 2009

COBOL

Works with: OpenCOBOL
       IDENTIFICATION DIVISION.
       PROGRAM-ID. Date-Format.

       DATA DIVISION.
       WORKING-STORAGE SECTION.

       01  Days-Area.
           03  Days-Data.
               05  FILLER PIC X(9) VALUE "Monday".
               05  FILLER PIC X(9) VALUE "Tuesday".
               05  FILLER PIC X(9) VALUE "Wednesday".
               05  FILLER PIC X(9) VALUE "Thursday".
               05  FILLER PIC X(9) VALUE "Friday".
               05  FILLER PIC X(9) VALUE "Saturday".
               05  FILLER PIC X(9) VALUE "Sunday".

           03  Days-Values REDEFINES Days-Data.
               05  Days-Table PIC X(9) OCCURS 7 TIMES.

       01  Months-Area.
           03  Months-Data.
               05  FILLER PIC X(9) VALUE "January".
               05  FILLER PIC X(9) VALUE "February".
               05  FILLER PIC X(9) VALUE "March".
               05  FILLER PIC X(9) VALUE "April".
               05  FILLER PIC X(9) VALUE "May".
               05  FILLER PIC X(9) VALUE "June".
               05  FILLER PIC X(9) VALUE "July".
               05  FILLER PIC X(9) VALUE "August".
               05  FILLER PIC X(9) VALUE "September".
               05  FILLER PIC X(9) VALUE "October".
               05  FILLER PIC X(9) VALUE "November".
               05  FILLER PIC X(9) VALUE "December".
              
           03  Months-Values REDEFINES Months-Data.
               05  Months-Table PIC X(9) OCCURS 12 TIMES.

       01  Current-Date-Str.
           03  Current-Year     PIC X(4).
           03  Current-Month    PIC X(2).
           03  Current-Day      PIC X(2).

       01  Current-Day-Of-Week  PIC 9.

       PROCEDURE DIVISION.
           MOVE FUNCTION CURRENT-DATE (1:8) TO Current-Date-Str
           
           DISPLAY Current-Year "-" Current-Month "-" Current-Day

           ACCEPT Current-Day-Of-Week FROM DAY-OF-WEEK
           DISPLAY
               FUNCTION TRIM(
                   Days-Table (FUNCTION NUMVAL(Current-Day-Of-Week)))
               ", "
               FUNCTION TRIM(
                   Months-Table (FUNCTION NUMVAL(Current-Month)))
               " "
               Current-Day
               ", "
               Current-Year
           END-DISPLAY

           GOBACK
           .

CoffeeScript

ECMAScript ≥ 5.1

Is supported by at least: Chrome 24, Firefox/Gecko 29, IE 11, Opera 15, and Node.js (at least as of 2015).

date = new Date

console.log date.toLocaleDateString 'en-GB',
    month:  '2-digit'
    day:    '2-digit'
    year:   'numeric'
.split('/').reverse().join '-'

console.log date.toLocaleDateString 'en-US',
    weekday: 'long'
    month:   'long'
    day:  'numeric'
    year: 'numeric'

Portable version

# JS does not have extensive formatting support out of the box.  This code shows
# how you could create a date formatter object.
DateFormatter = ->
  weekdays = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday']
  months = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December']
  pad = (n) ->
    if n < 10
      "0" + n
    else
      n

  brief: (date) ->
    month = 1 + date.getMonth()
    "#{date.getFullYear()}-#{pad month}-#{pad date.getDate()}"

  verbose: (date) ->
    weekday = weekdays[date.getDay()]
    month = months[date.getMonth()]
    day = date.getDate()
    year = date.getFullYear();
    "#{weekday}, #{month} #{day}, #{year}"
 
formatter = DateFormatter()
date = new Date()
console.log formatter.brief(date)
console.log formatter.verbose(date)
Output:
> coffee date_format.coffee 
2012-01-14
Saturday, January 14, 2012

ColdFusion

<cfoutput>
    #dateFormat(Now(), "YYYY-MM-DD")#<br />
    #dateFormat(Now(), "DDDD, MMMM DD, YYYY")#
</cfoutput>

Common Lisp

(defconstant *day-names* 
    #("Monday" "Tuesday" "Wednesday" "Thursday" "Friday" "Saturday" "Sunday"))
(defconstant *month-names*
    #(nil "January" "February" "March" "April" "May" "June" "July"
      "August" "September" "October" "November" "December"))

(multiple-value-bind (sec min hour date month year day daylight-p zone) (get-decoded-time)
    (format t "~4d-~2,'0d-~2,'0d~%" year month date)
    (format t "~a, ~a ~d, ~4d~%" 
        (aref *day-names* day) (aref *month-names* month) date year))

With the local-time library:

(local-time:format-timestring nil (local-time:now) :format '(:year  "-" (:month 2) "-" (:day 2)))
;; => "2019-11-13"
(local-time:format-timestring nil (local-time:now) :format '(:long-weekday ", " :long-month #\space (:day 2) ", " :year))
;; => "Wednesday, November 13, 2019"

Component Pascal

BlackBox Component Builder

MODULE DateFormat;
IMPORT StdLog, Dates;

PROCEDURE Do*;
VAR
	d: Dates.Date;
	resp: ARRAY 64 OF CHAR;
BEGIN
	Dates.GetDate(d);
	Dates.DateToString(d,Dates.short,resp);
	StdLog.String(":> " + resp);StdLog.Ln;
	Dates.DateToString(d,Dates.abbreviated,resp);
	StdLog.String(":> " + resp);StdLog.Ln;
	Dates.DateToString(d,Dates.long,resp);
	StdLog.String(":> " + resp);StdLog.Ln;
	Dates.DateToString(d,Dates.plainAbbreviated,resp);
	StdLog.String(":> " + resp);StdLog.Ln;
	Dates.DateToString(d,Dates.plainLong,resp);
	StdLog.String(":> " + resp);StdLog.Ln;
END Do;
END DateFormat.

Execute: ^Q DateFormat.Do

Output:

Spanish localization

:> 01/09/2013
:> dom, 01 de sep de 2013
:> domingo, 01 de septiembre de 2013
:> 01 de sep de 2013
:> 01 de septiembre de 2013

Crystal

Works with: Crystal version 0.33
require "time"

time = Time.local
puts time.to_s("%Y-%m-%d")
puts time.to_s("%A, %B %d, %Y")

D

Works with: D version DMD 1.026
Library: Tango
module datetimedemo ;

import tango.time.Time ; 
import tango.text.locale.Locale ;
import tango.time.chrono.Gregorian ;

import tango.io.Stdout ;

void main() {
    Gregorian g = new Gregorian ;
    Stdout.layout = new Locale; // enable Stdout to handle date/time format
    Time d = g.toTime(2007, 11, 10, 0, 0, 0, 0, g.AD_ERA) ;
    Stdout.format("{:yyy-MM-dd}", d).newline ;
    Stdout.format("{:dddd, MMMM d, yyy}", d).newline ;
    d = g.toTime(2008, 2, 1, 0, 0, 0, 0, g.AD_ERA) ;
    Stdout.format("{:dddd, MMMM d, yyy}", d).newline ;
}
Output:
2007-11-10
Saturday, November 10, 2007
Friday, February 1, 2008

Delphi

ShowMessage(FormatDateTime('yyyy-mm-dd', Now) +#13#10+ FormatDateTime('dddd, mmmm dd, yyyy', Now));
Output:
2022-02-16
Wednesday, February 16, 2022
Redirecting to 

Diego

me_lang(en)_cal(gregorian);
me_msg()_now()_format(yyyy-mm-dd);
me_msg()_now()_format(eeee, mmmm dd, yyyy);

EGL

// 2012-09-26
SysLib.writeStdout(StrLib.formatDate(DateTimeLib.currentDate(), "yyyy-MM-dd"));
// Wednesday, September 26, 2012
SysLib.setLocale("en", "US");
SysLib.writeStdout(StrLib.formatDate(DateTimeLib.currentDate(), "EEEE, MMMM dd, yyyy"));
Output:
2012-09-26
Wednesday, September 26, 2012

Elixir

Translation of: Erlang
Works with: Elixir version 1.4
defmodule Date_format do
  def iso_date, do: Date.utc_today |> Date.to_iso8601
  
  def iso_date(year, month, day), do: Date.from_erl!({year, month, day}) |> Date.to_iso8601
  
  def long_date, do: Date.utc_today |> long_date
   
  def long_date(year, month, day), do: Date.from_erl!({year, month, day}) |> long_date
  
  @months  Enum.zip(1..12, ~w[January February March April May June July August September October November December])
           |> Map.new
  @weekdays  Enum.zip(1..7, ~w[Monday Tuesday Wednesday Thursday Friday Saturday Sunday])
             |> Map.new
  def long_date(date) do
    weekday = Date.day_of_week(date)
    "#{@weekdays[weekday]}, #{@months[date.month]} #{date.day}, #{date.year}"
  end
end

IO.puts Date_format.iso_date
IO.puts Date_format.long_date
IO.puts Date_format.iso_date(2007,11,10)
IO.puts Date_format.long_date(2007,11,10)
Output:
2017-02-26
Sunday, February 26, 2017
2007-11-10
Saturday, November 10, 2007

Emacs Lisp

(format-time-string "%Y-%m-%d")
(format-time-string "%F")  ;; new in Emacs 24
;; => "2015-11-08"

(format-time-string "%A, %B %e, %Y")
;; => "Sunday, November  8, 2015"

%e is blank-padded day number, or %d for zero-padded. Month and weekday names follow the current locale. On a POSIX style system this is the usual LC_TIME or LC_ALL environment variables. GNU Emacs variable system-time-locale can override this if desired.

Erlang

-module(format_date).
-export([iso_date/0, iso_date/1, iso_date/3, long_date/0, long_date/1, long_date/3]).
-import(calendar,[day_of_the_week/1]).
-import(io,[format/2]).
-import(lists,[append/1]).

iso_date() -> iso_date(date()).
iso_date(Year, Month, Day) -> iso_date({Year, Month, Day}).
iso_date(Date) ->
  format("~4B-~2..0B-~2..0B~n", tuple_to_list(Date)).

long_date() -> long_date(date()).
long_date(Year, Month, Day) -> long_date({Year, Month, Day}).
long_date(Date = {Year, Month, Day}) ->
  Months =   { "January",   "February", "March",    "April",
               "May",       "June",     "July",     "August",
               "September", "October",  "November", "December" },
  Weekdays = { "Monday", "Tuesday",  "Wednesday", "Thursday",
               "Friday", "Saturday", "Sunday" },
  Weekday     = day_of_the_week(Date),
  WeekdayName = element(Weekday, Weekdays),
  MonthName   = element(Month, Months),
  append([WeekdayName, ", ", MonthName, " ", integer_to_list(Day), ", ",
          integer_to_list(Year)]).

Euphoria

constant days = {"Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"}
constant months = {"January","February","March","April","May","June",
    "July","August","September","October","November","December"}

sequence now

now = date()
now[1] += 1900

printf(1,"%d-%02d-%02d\n",now[1..3])
printf(1,"%s, %s %d, %d\n",{days[now[7]],months[now[2]],now[3],now[1]})

F#

"F# Interactive" session:

> open System;;
> Console.WriteLine( DateTime.Now.ToString("yyyy-MM-dd") );;
2010-08-13
> Console.WriteLine( "{0:D}", DateTime.Now );;
Friday, August 13, 2010

Factor

USING: formatting calendar io ;

now "%Y-%m-%d" strftime print
now "%A, %B %d, %Y" strftime print

Fantom

Today's date can be retrieved using 'Date.today'. The 'toLocale' method can be passed formatting information to determine how the date should be represented as a string. The rules are described at http://fantom.org/doc/sys/Date.html#toLocale

fansh> Date.today.toLocale("YYYY-MM-DD")
2011-02-24
fansh> Date.today.toLocale("WWWW, MMMM DD, YYYY")
Thursday, February 24, 2011

Forth

: .-0 ( n -- n )
  [char] - emit
  dup 10 < if [char] 0 emit then ;

: .short-date
  time&date ( s m h D M Y )
  1 u.r .-0 1 u.r .-0 1 u.r 
  drop drop drop ;

: str-table
  create ( n -- ) 0 do , loop
  does>  ( n -- str len ) swap cells + @ count ;

 here ," December"
 here ," November"
 here ," October"
 here ," September"
 here ," August"
 here ," July"
 here ," June"
 here ," May"
 here ," April"
 here ," March"
 here ," February"
 here ," January"
12 str-table months

 here ," Sunday"
 here ," Saturday"
 here ," Friday"
 here ," Thursday"
 here ," Wednesday"
 here ," Tuesday"
 here ," Monday"
7 str-table weekdays

\ Zeller's Congruence
: zeller ( m -- days since March 1 )
  9 + 12 mod 1-   26 10 */ 3 + ;

: weekday ( d m y -- 0..6 )   \ Monday..Sunday
  over 3 < if 1- then
  dup    4 /
  over 100 / -
  over 400 / +  +
  swap zeller + +
  1+ 7 mod ;

: 3dup   dup 2over rot ;

: .long-date
  time&date ( s m h D M Y )
  3dup weekday weekdays type ." , "
  >R 1- months type space 1 u.r ." , " R> .
  drop drop drop ;

Version 2: Meta Language

Forth is less of a language and more of an extensible toolkit of simple routines. This version attempts to demonstrate using the simple routines to extend Forth. Then using the language extensions and the power of concatenative language to solve the problem. This solution could create numerous date formats as one line definitions now that we have our "date" words defined. Typically these extensions would be saved as a library file.

\ Build up a "language" for date formatting

\ utility words
: UNDER+  ( a b c -- a+c b )  ROT + SWAP ;
: 3DUP    ( a b c -- a b c a b c ) 2 PICK 2 PICK 2 PICK ;
: WRITE$  ( caddr -- ) COUNT TYPE ;  \ print a counted string
: ','     ( -- )  ." , "  ;
: '-'     ( -- )  ." -"   ;

\ day of week calculation
\ "This is an algorithm I've carried with me for 35 years,
\  originally in Assembler and Fortran II."
\  It counts the number of days from March 1, 1900."
\                                    Wil Baden R.I.P.
\ *****************************************************
\ **WARNING** only good until 2078 on 16 bit machine **
\ *****************************************************
DECIMAL
: CDAY    ( dd mm yyyy -- century_day )
      -3 UNDER+  OVER  0<
      IF   12 UNDER+  1-   THEN
      1900 -  1461 4 */   SWAP 306 *  5 +  10 /  + +  ;

: DOW   ( cday -- day_of_week ) 2 + 7 MOD 1+ ; ( 7 is Sunday)

\ formatted number printers
: ##.   ( n -- )  0 <#  # #      #> TYPE ;
: ####. ( n -- )  0 <#  # # # #  #> TYPE ;

\ make some string list words
: LIST[   ( -- ) !CSP  0 C,  ;         \ list starts with 0 bytes, record stack pos.
: ]LIST   ( -- ) 0 C, ALIGN ?CSP ;     \ '0' ends list, check stack

: NEXT$   ( $[1] -- $[2] )    COUNT + ;               \ get next string
: NTH$    ( n list -- $addr ) SWAP 0 DO NEXT$ LOOP ;  \ get nth string

: "       ( -- ) [CHAR] " WORD  C@ CHAR+ ALLOT ;      \ compile text upto "

\ make the lists
CREATE MONTHS
  LIST[ " January" " February"  " March"   " April" " May" " June" " July"
        " August"  " September" " October" " November" " December" ]LIST

CREATE DAYS
  LIST[ " Monday" " Tuesday" " Wednesday"  " Thursday" 
        " Friday" " Saturday" " Sunday" ]LIST

\ expose lists as indexable arrays that print the string
: ]MONTH$.  ( n -- )  MONTHS NTH$ WRITE$ ;
: ]DAY$.    ( n -- )  DAYS NTH$ WRITE$ ;


\ ===========================================
\ Rosetta Task Code Begins

\ Rosetta Date Format 1
: Y-M-D.     ( d m y -- )  ####. '-' ##. '-' ##. ;

\ Rosetta Date Format 2
: LONG.DATE ( d m y -- )
    3DUP CDAY DOW ]DAY$. ',' -ROT ]MONTH$. SPACE ##.  ','  ####.  ;


Test at the Forth Console

 5 7 2018 Y-M-D. 2018-07-05 ok
  ok
5 7 2018 LONG.DATE Thursday, July 05, 2018 ok

Fortran

Works with: Fortran version 95 and later

The subroutine DATE_AND_TIME does not return day of week information so we have to write our own function for that

PROGRAM DATE

  IMPLICIT NONE
  
  INTEGER :: dateinfo(8), day
  CHARACTER(9) :: month, dayname
     
  CALL DATE_AND_TIME(VALUES=dateinfo)
  SELECT CASE(dateinfo(2))
    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"
  END SELECT

  day = Day_of_week(dateinfo(3), dateinfo(2), dateinfo(1))

  SELECT CASE(day)
    CASE(0)
      dayname = "Saturday"
    CASE(1)
      dayname = "Sunday"
    CASE(2)
      dayname = "Monday"
    CASE(3)
      dayname = "Tuesday"
    CASE(4)
      dayname = "Wednesday"
    CASE(5)
      dayname = "Thursday"
    CASE(6)
      dayname = "Friday"
  END SELECT
  
  WRITE(*,"(I0,A,I0,A,I0)") dateinfo(1),"-", dateinfo(2),"-", dateinfo(3)
  WRITE(*,"(4(A),I0,A,I0)") trim(dayname), ", ", trim(month), " ", dateinfo(3), ", ", dateinfo(1)

CONTAINS

  FUNCTION Day_of_week(d, m, y)
    INTEGER :: Day_of_week, j, k
    INTEGER, INTENT(IN) :: d, m, y
    
    j = y / 100
    k = MOD(y, 100)
    Day_of_week = MOD(d + (m+1)*26/10 + k + k/4 + j/4 + 5*j, 7)
  END FUNCTION Day_of_week

END PROGRAM DATE
Output:
2008-12-14
Sunday, December 14, 2008

FreeBASIC

' FB 1.05.0 Win64

#Include "vbcompat.bi"

Dim d As Long = Now
Print "This example was created on : "; Format(d, "yyyy-mm-dd")
Print "In other words on : "; Format(d, "dddd, mmmm d, yyyy")
Print
Print "Press any key to quit the program"
Sleep
Output:
This example was created on : 2016-10-02
In other words on : Sunday, October 2, 2016

Free Pascal

program Format_Date_Time;
uses
  SysUtils;
begin
  WriteLn(FormatDateTime('yyyy-mm-dd', Now) +#13#10+ FormatDateTime('dddd, mmmm dd, yyyy', Now));
end.
Output:
2022-02-16
Wednesday, February 16, 2022

Frink

println[now[] -> ### yyyy-MM-dd ###]
println[now[] -> ### EEEE, MMMM d, yyyy ###]

FunL

println( format('%tF', $date) )
println( format('%1$tA, %1$tB %1$td, %1$tY', $date) )

FutureBasic

window 1

print date(@"yyyy-MM-dd")
print date(@"EEEE, MMMM dd, yyyy")

HandleEvents

Gambas

You can run this code. Copy the code, click this link, paste it in and press 'Run !'

Public Sub Main()

Print Format(Now, "yyyy - mm - dd")
Print Format(Now, "dddd, mmmm dd, yyyy")

End

Output:

2017 - 05 - 27
Saturday, May 27, 2017

Go

In an interesting design, you specify your format by providing the format for the date and time 01/02 03:04:05PM '06 -0700

package main

import "time"
import "fmt"

func main() {
    fmt.Println(time.Now().Format("2006-01-02"))
    fmt.Println(time.Now().Format("Monday, January 2, 2006"))
}
Output:
2011-12-02
Friday, December 2, 2011

Groovy

Solution:

def isoFormat = { date -> date.format("yyyy-MM-dd") }
def longFormat = { date -> date.format("EEEE, MMMM dd, yyyy") }

Test Program:

def now = new Date()
println isoFormat(now)
println longFormat(now)

Haskell

import Data.Time
       (FormatTime, formatTime, defaultTimeLocale, utcToLocalTime,
        getCurrentTimeZone, getCurrentTime)

formats :: FormatTime t => [t -> String]
formats = (formatTime defaultTimeLocale) <$>  ["%F", "%A, %B %d, %Y"]

main :: IO ()
main = do
  t <- pure utcToLocalTime <*> getCurrentTimeZone <*> getCurrentTime
  putStrLn $ unlines (formats <*> pure t)

Sample output:

2017-06-05
Monday, June 05, 2017

HicEst

   CHARACTER string*40

   WRITE(Text=string, Format='UCCYY-MM-DD') 0 ! string: 2010-03-13

   ! the U-format to write date and time uses ',' to separate additional output formats
   ! we therefore use ';' in this example and change it to ',' below:
   WRITE(Text=string,Format='UWWWWWWWWW; MM DD; CCYY') 0 ! string = "Saturday ; 03 13; 2010"
   READ(Text=string) month ! first numeric value = 3 (no literal month name available)
   EDIT(Text='January,February,March,April,May,June,July,August,September,October,November,December', ITeM=month, Parse=cMonth) ! cMonth = "March"
   ! change now string = "Saturday ; 03 13; 2010" to "Saturday, March 13, 2010":
   EDIT(Text=string, Right=' ', Mark1, Right=';', Right=3, Mark2, Delete, Insert=', '//cMonth, Right=';', RePLaceby=',')

 END

Icon and Unicon

procedure main()
write(map(&date,"/","-"))
write(&dateline ? tab(find(&date[1:5])+4))
end
Output:
2011-02-01
Tuesday, February 1, 2011

J

Short format using built in formatting:

   6!:0 'YYYY-MM-DD'
2010-08-19

Verb to show custom format:

require 'dates system/packages/misc/datefmt.ijs'
days=:;:'Sunday Monday Tuesday Wednesday Thursday Friday Saturday'
fmtDate=: [:((days ;@{~ weekday),', ',ms0) 3 {.]

   fmtDate 6!:0 ''
Thursday, August 19, 2010

Java

public static void main(String[] args) {
    long millis = System.currentTimeMillis();
    System.out.printf("%tF%n", millis);
    System.out.printf("%tA, %1$tB %1$td, %1$tY%n", millis);
}
2023-05-10
Wednesday, May 10, 2023


An alternate demonstration

import java.util.Calendar;
import java.util.GregorianCalendar;
import java.text.DateFormatSymbols;
import java.text.DateFormat;
public class Dates{
 public static void main(String[] args){
  Calendar now = new GregorianCalendar(); //months are 0 indexed, dates are 1 indexed
  DateFormatSymbols symbols = new DateFormatSymbols(); //names for our months and weekdays

  //plain numbers way
  System.out.println(now.get(Calendar.YEAR)  + "-" + (now.get(Calendar.MONTH) + 1) + "-" + now.get(Calendar.DATE));

  //words way
  System.out.print(symbols.getWeekdays()[now.get(Calendar.DAY_OF_WEEK)] + ", ");
  System.out.print(symbols.getMonths()[now.get(Calendar.MONTH)] + " ");
  System.out.println(now.get(Calendar.DATE) + ", " + now.get(Calendar.YEAR));
 }
}

Better: use a library, see http://sourceforge.net/apps/mediawiki/threeten/index.php?title=ThreeTen

Java 8 Date Time API

import java.time.LocalDate;
import java.time.format.DateTimeFormatter;
public class Dates
{
 public static void main(final String[] args)
 {
  //using DateTimeFormatter
  LocalDate date = LocalDate.now();
  DateTimeFormatter dtFormatter = DateTimeFormatter.ofPattern("yyyy MM dd");

  System.out.println(dtFormatter.format(date));
 }
}

Java Util Date API

import java.text.SimpleDateFormat;
import java.util.Date;

public class DateFormat {
    public static void main(String[]args){
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
        SimpleDateFormat formatLong = new SimpleDateFormat("EEEE, MMMM dd, yyyy");
        System.out.println(format.format(new Date()));
        System.out.println(formatLong.format(new Date()));
    }
}

JavaScript

JavaScript does not have any built-in strftime-type functionality.

var now = new Date(),
    weekdays = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'],
    months   = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'],
    fmt1 = now.getFullYear() + '-' + (1 + now.getMonth()) + '-' + now.getDate(),
    fmt2 = weekdays[now.getDay()] + ', ' + months[now.getMonth()] + ' ' + now.getDate() + ', ' + now.getFullYear();
console.log(fmt1);
console.log(fmt2);
2010-1-12
Tuesday, January 12, 2010

Joy

DEFINE weekdays == ["Monday" "Tuesday" "Wednesday" "Thursday" "Friday" "Saturday" "Sunday"];
       months   == ["January" "February" "March" "April" "May" "June" "July" "August"
                    "September" "October" "November" "December" ].

time localtime [[0 at 'd 4 4 format] ["-"] [1 at 'd 2 2 format] ["-"] [2 at 'd 2 2 format]]
[i] map [putchars] step '\n putch pop.

time localtime [[8 at pred weekdays of] [", "] [1 at pred months of] [" "] [2 at 'd 1 1 format]
[", "] [0 at 'd 4 4 format]] [i] map [putchars] step '\n putch pop.

jq

Works with: jq version with strftime
$ jq -n 'now | (strftime("%Y-%m-%d"), strftime("%A, %B %d, %Y"))'
"2015-07-02"
"Thursday, July 02, 2015"

WARNING: prior to July 2, 2015, there was a bug in jq affecting the display of the "day of week" (wday) and the "day of the year" (yday).

Julia

Works with: Julia version 0.6
ts = Dates.today()

println("Today's date is:")
println("\t$ts")
println("\t", Dates.format(ts, "E, U dd, yyyy"))
Output:
Today's date is:
	2018-01-05
	Friday, January 05, 2018

Kotlin

// version 1.0.6

import java.util.GregorianCalendar

fun main(args: Array<String>) {
    val now = GregorianCalendar()
    println("%tF".format(now))
    println("%tA, %1\$tB %1\$te, %1\$tY".format(now))
}
Output:
2017-01-16
Monday, January 16, 2017

langur

var .now = dt//
var .format1 = "2006-01-02"
var .format2 = "Monday, January 2, 2006"
writeln $"\.now:dt.format1;"
writeln $"\.now:dt.format2;"
var .now = dt//
writeln $"\.now:dt(2006-01-02);"
writeln $"\.now:dt(Monday, January 2, 2006);"
writeln toString dt//, "2006-01-02"
writeln toString dt//, "Monday, January 2, 2006"
Output:
2020-03-26
Thursday, March 26, 2020

Langur is using the Go time package, and using its formatting method for output. It expects the following parts in a format string.

year: 2006 or 06
month: 01 or 1
month name: Jan or January
month day: 02 or _2 or 2
weekday name: Mon or Monday
hour: 03 or 3 or 15
minute: 04 or 4
second: 05 or 5
AM/PM: PM or pm
time zone offset: -07:00 or -0700 or -07
time zone name: MST

Lasso

date('11/10/2007')->format('%Q') // 2007-11-10
date('11/10/2007')->format('EEEE, MMMM d, YYYY') //Saturday, November 10, 2007

Liberty BASIC

'Display the current date in the formats of "2007-11-10"
d$=date$("yyyy/mm/dd")
print word$(d$,1,"/")+"-"+word$(d$,2,"/")+"-"+word$(d$,3,"/")

'and "Sunday, November 10, 2007".
day$(0)="Tuesday"
day$(1)="Wednesday"
day$(2)="Thursday"
day$(3)="Friday"
day$(4)="Saturday"
day$(5)="Sunday"
day$(6)="Monday"
theDay = date$("days") mod 7
print day$(theDay);", ";date$()

' month in full
year=val(word$(d$,1,"/"))
month=val(word$(d$,2,"/"))
day=val(word$(d$,3,"/"))
weekDay$="Tuesday Wednesday Thursday Friday Saturday Sunday Monday"
monthLong$="January February March April May June July August September October November December"

print word$(weekDay$,theDay+1);", ";word$(monthLong$,month);" ";day;", ";year


LiveCode

on mouseUp pButtonNumber
   put the date into tDate
   convert tDate to dateItems
   put item 1 of tDate & "-" & item 2 of tDate & "-" & item 3 of tDate & return into tMyFormattedDate
   put tMyFormattedDate & the long date
end mouseUp

Works with: UCB Logo

A bit of a cheat since Logo has no standard built-in time and date functions, but UCB Logo can call out to the shell, so:

print first shell [date +%F]
print first shell [date +"%A, %B %d, %Y"]
Output:
2020-09-16
Wednesday, September 16, 2020

Lua

print( os.date( "%Y-%m-%d" ) )
print( os.date( "%A, %B %d, %Y" ) )

M2000 Interpreter

Print str$(today, "yyyy-mm-dd")
Print str$(today, "dddd, mmm, dd, yyyy")

Maple

with(StringTools); 
FormatTime("%Y-%m-%d")
FormatTime("%A,%B %d, %y")

Mathematica/Wolfram Language

DateString[{"Year", "-", "Month", "-", "Day"}]
DateString[{"DayName", ", ", "MonthName", " ", "Day", ", ", "Year"}]

MATLAB / Octave

>> datestr(now,'yyyy-mm-dd')

ans =

2010-06-18

>> datestr(now,'dddd, mmmm dd, yyyy')

ans =

Friday, June 18, 2010

min

Works with: min version 0.19.3
("YYYY-MM-dd" "dddd, MMMM dd, YYYY") ('timestamp dip tformat puts!) foreach
Output:
2019-04-02
Tuesday, April 02, 2019

MiniScript

import "dateTime"

print dateTime.now("yyyy-MM-dd")
print dateTime.now("dddd, MMMM d, yyyy")
Output:
2023-12-28
Thursday, December 28, 2023

mIRC Scripting Language

echo -ag $time(yyyy-mm-dd)
echo -ag $time(dddd $+ $chr(44) mmmm dd $+ $chr(44) yyyy)

MUMPS

Works with: Intersystems' Caché version (all versions)

Functions starting with 'Z' or '$Z' are implementation specific.

DTZ 
 WRITE !,"Date format 3: ",$ZDATE($H,3)
 WRITE !,"Or ",$ZDATE($H,12),", ",$ZDATE($H,9)
 QUIT

MUMPS contains the integer number of days since December 31, 1840 in the first part of the system variable $HOROLOG.

Works with: MUMPS version all
DTM(H)
 ;You can pass an integer, but the default is to use today's value
 SET:$DATA(H)=0 H=$HOROLOG
 NEW Y,YR,RD,MC,MO,DA,MN,DN,DOW
 SET MN="January,February,March,April,May,June,July,August,September,October,November,December"
 SET DN="Sunday,Monday,Tuesday,Wednesday,Thursday,Friday,Saturday"
 SET MC="31,28,31,30,31,30,31,31,30,31,30,31"
 SET Y=+H\365.25 ;This shouldn't be an approximation in production code
 SET YR=Y+1841 ;Y is the offset from the epoch in years
 SET RD=((+H-(Y*365.25))+1)\1 ;How far are we into the year?
 SET $P(MC,",",2)=$S(((YR#4=0)&(YR#100'=0))!((YR#100=0)&(YR#400=0))=0:28,1:29) ;leap year correction
 SET MO=1,RE=RD FOR  QUIT:RE<=$P(MC,",",MO)  SET RE=RE-$P(MC,",",MO),MO=MO+1
 SET DA=RE+1
 SET DOW=(H#7)+5 ;Fencepost issue - the first piece is 1
 ;add padding as needed
 SET:$L(MO)<2 MO="0"_MO
 SET:$L(DA)<2 DA="0"_DA
 WRITE !,YR,"-",MO,"-",DA
 WRITE !,$P(DN,",",DOW),", ",$P(MN,",",MO)," ",DA,", ",YR
 KILL Y,YR,RD,MC,MO,DA,MN,DN,DOW
 QUIT
Demos:
USER>D DTM^ROSETTA
 
2010-06-24
Thursday, June 24, 2010
USER>D DTM^ROSETTA(1234)
 
1844-05-19
Saturday, May 19, 1844
USER>D DTZ^ROSETTA
 
Date format 3: 2010-06-24
Or Thursday, June 24, 2010

Nanoquery

import Nanoquery.Util

d = new(Date)
println d.getYear() + "-" + d.getMonth() + "-" + d.getDay()
println d.getDayOfWeek() + ", " + d.getMonthName() + " " + d.getDay() + ", " + d.getYear()

Neko

/**
 <doc>
 <h2>Date format</h2>
 <p>Neko uses Int32 to store system date/time values.
 And lib C strftime style formatting for converting to string form</p>
 </doc>
*/

var date_now = $loader.loadprim("std@date_now", 0)
var date_format = $loader.loadprim("std@date_format", 2)

var now = date_now()
$print(date_format(now, "%F"), "\n")
$print(date_format(now, "%A, %B %d, %Y"), "\n")
Output:
prompt$ nekoc date-format.neko
prompt$ neko date-format.n
2018-11-13
Tuesday, November 13, 2018

NetRexx

import java.text.SimpleDateFormat
say SimpleDateFormat("yyyy-MM-dd").format(Date())
say SimpleDateFormat("EEEE, MMMM dd, yyyy").format(Date())
Output:
2019-02-10
Sonntag, Februar 10, 2019

NewLISP

; file:   date-format.lsp
; url:    http://rosettacode.org/wiki/Date_format
; author: oofoe 2012-02-01

; The "now" function returns the current time as a list. A time zone
; offset in minutes can be supplied. The example below is for Eastern
; Standard Time. NewLISP's implicit list indexing is used to extract
; the first three elements of the returned list (year, month and day).

(setq n (now (* -5 60)))
(println "short: " (format "%04d-%02d-%02d" (n 0) (n 1) (n 2)))

; The "date-value" function returns the time in seconds from the epoch
; when used without arguments. The "date" function converts the
; seconds into a time representation specified by the format string at
; the end. The offset argument ("0" in this example) specifies a
; time-zone offset in minutes.

(println "short: " (date (date-value) 0 "%Y-%m-%d"))

; The time formatting is supplied by the underlying C library, so
; there may be differences on certain platforms. Particularly, leading
; zeroes in day numbers can be suppressed with "%-d" on Linux and
; FreeBSD, "%e" on OpenBSD, SunOS/Solaris and Mac OS X. Use "%#d" for
; Windows.

(println "long:  " (date (date-value) 0 "%A, %B %#d, %Y"))

; By setting the locale, the date will be displayed appropriately:

(set-locale "japanese")
(println "long:  " (date (date-value) 0 "%A, %B %#d, %Y"))

(exit)
Output:
short: 2012-02-01
short: 2012-02-01
long:  Wednesday, February 1, 2012
long:  水曜日, 2月 1, 2012

Nim

import times

var t = now()
echo(t.format("yyyy-MM-dd"))
echo(t.format("dddd',' MMMM d',' yyyy"))

Objeck

use IO;
use Time;

bundle Default {
  class CurrentDate {
    function : Main(args : String[]) ~ Nil {
      t := Date->New();
      Console->Print(t->GetYear())->Print("-")->Print(t->GetMonth())->Print("-")
        ->PrintLine(t->GetDay());
      Console->Print(t->GetDayName())->Print(", ")->Print(t->GetMonthName())
        ->Print(" ")->Print(t->GetDay())->Print(", ")
        ->PrintLine(t->GetYear());
    }
  }
}
Output:
2012-5-22
Sunday, May 22, 2012

Objective-C

NSLog(@"%@", [NSDate date]);
NSLog(@"%@", [[NSDate date] descriptionWithCalendarFormat:@"%Y-%m-%d" timeZone:nil locale:nil]);
NSLog(@"%@", [[NSDate date] descriptionWithCalendarFormat:@"%A, %B %d, %Y" timeZone:nil locale:nil]);
Works with: Mac OS X version 10.4+
Works with: iOS
NSLog(@"%@", [NSDate date]);
NSDateFormatter *dateFormatter = [[NSDateFormat alloc] init];
[dateFormatter setDateFormat:@"yyyy-MM-dd"];
NSLog(@"%@", [dateFormatter stringFromDate:[NSDate date]]);
[dateFormatter setDateFormat:@"EEEE, MMMM d, yyyy"];
NSLog(@"%@", [dateFormatter stringFromDate:[NSDate date]]);

OCaml

# #load "unix.cma";;
# open Unix;;

# let t = time() ;;
val t : float = 1219997516.

# let gmt = gmtime t ;;
val gmt : Unix.tm =
  {tm_sec = 56; tm_min = 11; tm_hour = 8; tm_mday = 29; tm_mon = 7;
   tm_year = 108; tm_wday = 5; tm_yday = 241; tm_isdst = false}

# Printf.sprintf "%d-%02d-%02d" (1900 + gmt.tm_year) (1 + gmt.tm_mon) gmt.tm_mday ;;
- : string = "2008-08-29"
let months = [| "January"; "February"; "March"; "April"; "May"; "June";
      "July"; "August"; "September"; "October"; "November"; "December" |] 

let days = [| "Sunday"; "Monday"; "Tuesday";  (* Sunday is 0 *)
      "Wednesday"; "Thursday"; "Friday"; "Saturday" |]

# Printf.sprintf "%s, %s %d, %d"
      days.(gmt.tm_wday)
      months.(gmt.tm_mon)
      gmt.tm_mday
      (1900 + gmt.tm_year) ;;
- : string = "Friday, August 29, 2008"

ooRexx

/* REXX */
dats='20071123'
Say date('I',dats,'S')
Say date('W',dats,'S')',' date('M',dats,'S') substr(dats,7,2)',' left(dats,4)
Say date('W',dats,'S')',' date('M',dats,'S') translate('gh, abcd',dats,'abcdefgh')
dati=date('I')
Say dati
Say date('W',dati,'I')',' date('M',dati,'I') translate('ij, abcd',dati,'abcdefghij')
Output:
2007-11-23

Friday, November 23, 2007 Friday, November 23, 2007 2020-06-05 Friday, June 05, 2020

OxygenBasic

extern lib "kernel32.dll"

'http://msdn.microsoft.com/en-us/library/windows/desktop/ms724950(v=vs.85).aspx

typedef struct _SYSTEMTIME {
  WORD wYear;
  WORD wMonth;
  WORD wDayOfWeek;
  WORD wDay;
  WORD wHour;
  WORD wMinute;
  WORD wSecond;
  WORD wMilliseconds;
} SYSTEMTIME, *PSYSTEMTIME;

void GetSystemTime(SYSTEMTIME*t);
void GetLocalTime(SYSTEMTIME*t);

end extern

SYSTEMTIME t
'GetSystemTime t 'GMT (Greenwich Mean Time)
GetLocalTime t

String WeekDay[7]={"Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"}
String MonthName[12]={"January","February","March","April","May","June","July","August","September","October","November","December"}
String month=str t.wMonth : if len(month)<2 then month="0"+month
String day=str t.wDay : if len(day)<2 then day="0"+day
'
print "" t.wYear "-" month "-" day
print WeekDay[t.wDayOfWeek+1 and 7 ] " " MonthName[t.wMonth and 31] " " t.wDay " " t.wYear

Oz

Getting the current local date is easy, but we have to do the formatting manually.

declare
  WeekDays = unit(0:"Sunday" "Monday" "Tuesday" "Wednesday"
                  "Thursday" "Friday" "Saturday")
  Months = unit(0:"January" "February" "March" "April"
                "May" "June" "July" "August" "September"
                "October" "November" "December")

  fun {DateISO Time}
     Year = 1900 + Time.year
     Month = Time.mon + 1
  in
     Year#"-"#{Align Month}#"-"#{Align Time.mDay}
  end

  fun {DateLong Time}
     Year = 1900 + Time.year
  in
     WeekDays.(Time.wDay)#", "#Months.(Time.mon)#" "#Time.mDay#", "#Year
  end

  fun {Align Num}
     if Num < 10 then "0"#Num else Num end
  end
in
  {System.showInfo {DateISO {OS.localTime}}}
  {System.showInfo {DateLong {OS.localTime}}}

Pascal

Works with: Turbo Pascal version 5.5
program dateform;
uses DOS;

{ Format digit with leading zero }
function lz(w: word): string;
var
  s: string;
begin
  str(w,s);
  if length(s) = 1 then
    s := '0' + s;
  lz := s
end;

function m2s(mon: integer): string;
begin
  case mon of
     1: m2s := 'January';
     2: m2s := 'February';
     3: m2s := 'March';
     4: m2s := 'April';
     5: m2s := 'May';
     6: m2s := 'June';
     7: m2s := 'July';
     8: m2s := 'August';
     9: m2s := 'September';
    10: m2s := 'October';
    11: m2s := 'November';
    12: m2s := 'December'
  end
end;

function d2s(dow: integer): string;
begin
  case dow of
    0: d2s := 'Sunday';
    1: d2s := 'Monday';
    2: d2s := 'Tueday';
    3: d2s := 'Wednesday';
    4: d2s := 'Thursday';
    5: d2s := 'Friday';
    6: d2s := 'Saturday'
  end
end;

var
  yr,mo,dy,dow: word;
  mname,dname: string;

begin
  GetDate(yr,mo,dy,dow);
  writeln(yr,'-',lz(mo),'-',lz(dy));
  mname := m2s(mo); dname := d2s(dow);
  writeln(dname,', ',mname,' ',dy,', ',yr)
end.
Output:
2010-07-30
Friday, July 30, 2010

Perl

Library: POSIX
use POSIX;

print strftime('%Y-%m-%d', 0, 0, 0, 10, 10, 107), "\n";
print strftime('%A, %B %d, %Y', 0, 0, 0, 10, 10, 107), "\n";
Output:
with locales C
2007-11-10
Saturday, November 10, 2007
Output:
with locales cs_CZ.UTF-8
2007-11-10
Sobota, listopad 10, 2007

Actual date:

use POSIX;

print strftime('%Y-%m-%d', localtime), "\n";
print strftime('%A, %B %d, %Y', localtime), "\n";
Output:
with locales C
2008-02-13
Wednesday, February 13, 2008

Phix

Library: Phix/basics
with javascript_semantics
include builtins\timedate.e
?format_timedate(date(),"YYYY-MM-DD")
?format_timedate(date(),"Dddd, Mmmm d, YYYY")
Output:
"2015-09-20"
"Sunday, September 20, 2015"

PHP

Formatting rules: http://www.php.net/date

<?php
echo date('Y-m-d', time())."\n";
echo date('l, F j, Y', time())."\n";
?>

PicoLisp

(let (Date (date)  Lst (date Date))
   (prinl (dat$ Date "-"))             # 2010-02-19
   (prinl                              # Friday, February 19, 2010
      (day Date)
      ", "
      (get *MonFmt (cadr Lst))
      " "
      (caddr Lst)
      ", "
      (car Lst) ) )

Pike

object cal = Calendar.ISO.Day();
write( cal->format_ymd() +"\n" );
string special = sprintf("%s, %s %d, %d",
                         cal->week_day_name(),
                         cal->month_name(),
                         cal->month_day(),
                         cal->year_no());
write( special +"\n" );
Output:
2020-01-03
Friday, January 3, 2020

PL/I

Version 1

df: proc Options(main);
 declare day_of_week(7) character (9) varying initial(
    'Sunday','Monday','Tuesday','Wednesday',
    'Thursday','Friday','Saturday');
 declare today character (9);

 today = datetime('YYYYMMDD');
 put edit(substr(today,1,4),'-',substr(today,5,2),'-',substr(today,7))
  (A);

 today = datetime('MmmDDYYYY');
 put skip edit(day_of_week(weekday(days())),', ') (A);
 put edit(substr(today,1,3),' ',substr(today,4,2),', ',
          substr(today,6,4))(A);
 end;
Output:
2013-11-02
Saturday, Nov 02, 2013

Version 2

 df: proc Options(Main);
 declare day_of_week(7) character(9) varying initial(
    'Sunday','Monday','Tuesday','Wednesday',
    'Thursday','Friday','Saturday');
 declare today character(8);
 declare month(12) character(10) varying initial(
    'January','February','March','April','May','June','July',
    'August','September','October','November','December');

 Put edit(translate('abcd-ef-gh',datetime('YYYYMMDD'),'abcdefgh'))(a);
 today = datetime('MMDDYYYY');

 put skip edit(day_of_week(weekday()),', ') (A);
 put edit(month(substr(today,1,2)),' ',substr(today,3,2),', ',
          substr(today,5,4))(A);
 End;
Output:
2013-11-02
Saturday, November 02, 2013

PowerShell

"{0:yyyy-MM-dd}" -f (Get-Date)
"{0:dddd, MMMM d, yyyy}" -f (Get-Date)
# or
(Get-Date).ToString("yyyy-MM-dd")
(Get-Date).ToString("dddd, MMMM d, yyyy")

Note: The names of months and days follow the currently set locale but otherwise the format is unchanged.

Prolog

Works with: SWI-Prolog version 6
display_date :-
    get_time(Time),
    format_time(atom(Short), '%Y-%M-%d',      Time),
    format_time(atom(Long),  '%A, %B %d, %Y', Time),
    format('~w~n~w~n', [Short, Long]).

PureBasic

Works with: PureBasic version 4.41
;Declare Procedures
Declare.s MonthInText()
Declare.s DayInText()

;Output the requested strings
Debug FormatDate("%yyyy-%mm-%dd", Date()) 
Debug DayInText() + ", " + MonthInText() + FormatDate(" %dd, %yyyy", Date()) 

;Used procedures
Procedure.s DayInText()
  Protected d$
  Select DayOfWeek(Date())
    Case 1: d$="Monday"
    Case 2: d$="Tuesday"
    Case 3: d$="Wednesday"
    Case 4: d$="Thursday"
    Case 5: d$="Friday"
    Case 6: d$="Saturday"
    Default: d$="Sunday"
  EndSelect
  ProcedureReturn d$
EndProcedure

Procedure.s MonthInText()
  Protected  m$
  Select Month(Date())  
    Case 1: m$="January"
    Case 2: m$="February"
    Case 3: m$="March"
    Case 4: m$="April"
    Case 5: m$="May"
    Case 6: m$="June"
    Case 7: m$="July"
    Case 8: m$="August"
    Case 9: m$="September"
    Case 10:m$="October"
    Case 11:m$="November"
    Default:m$="December"
  EndSelect
  ProcedureReturn m$
EndProcedure

Python

Formatting rules: http://docs.python.org/lib/module-time.html (strftime)

import datetime
today = datetime.date.today()
# The first requested format is a method of datetime objects:
today.isoformat()
# For full flexibility, use the strftime formatting codes from the link above:
today.strftime("%A, %B %d, %Y")
# This mechanism is integrated into the general string formatting system.
# You can do this with positional arguments referenced by number
"The date is {0:%A, %B %d, %Y}".format(d)
# Or keyword arguments referenced by name
"The date is {date:%A, %B %d, %Y}".format(date=d)
# Since Python 3.6, f-strings allow the value to be inserted inline
f"The date is {d:%A, %B %d, %Y}"

R

strftime is short for "string format time".

now <- Sys.time()
strftime(now, "%Y-%m-%d")
strftime(now, "%A, %B %d, %Y")

Racket

Module racket/date is included within #lang racket However its date to string facilities only provide ISO-8601 (which provides the "2007-11-10" format) but nothing that strictly provides "<Full day name>, <Full month name> ...".

We therefore need to import SRFI/19 "SRFI 19: Time Data Types and Procedures" (it's a standard Racket package).

See: http://srfi.schemers.org/srfi-19/srfi-19.html

#lang racket
(require srfi/19)

;;; The first required format is an ISO-8601 year-month-day format, predefined
;;; as ~1 in date->string
(displayln (date->string (current-date) "~1"))

;;; You should be able to see how each of the components of the following format string
;;; work...
;;; ~d is zero padded day of month:
(displayln (date->string (current-date) "~A, ~B ~d, ~Y"))
;;; ~e is space padded day of month:
(displayln (date->string (current-date) "~A, ~B ~e, ~Y"))

both ~d and ~e satisfy the format required, since the "10" part of that date is 2-digit

Output:
2013-04-02
Tuesday, April 02, 2013
Tuesday, April  2, 2013

Raku

(formerly Perl 6)

use DateTime::Format;

my $dt = DateTime.now;

say strftime('%Y-%m-%d', $dt);
say strftime('%A, %B %d, %Y', $dt);

The built-in Date and DateTime classes both offer support for the ISO format:

my $d = Date.today;

say $d.yyyy-mm-dd;

They don't include the longer format specified in the task, but you can always roll your own formatter instead of importing the library:

my @months = <January February March April May June July
              August September October November December>;
my @days = <Monday Tuesday Wednesday Thursday Friday Saturday Sunday>;
my $us-long = sub ($self) { "{@days[$self.day-of-week - 1]}, {@months[$self.month - 1]} {$self.day}, {$self.year}" };
my $d = Date.today :formatter($us-long);

say $d.yyyy-mm-dd; # still works
say $d; # uses our formatter sub

Raven

time int as today

Short form:

today '%Y-%m-%d' date

Long form:

today '%A, %B %d, %Y' date

REBOL

REBOL [
	Title: "Date Formatting"
	URL: http://rosettacode.org/wiki/Date_format
]

; REBOL has no built-in pictured output.

zeropad: func [pad n][
    n: to-string n
    insert/dup n "0" (pad - length? n)
    n 
]
d02: func [n][zeropad 2 n]

print now ; Native formatting.

print rejoin [now/year  "-"  d02 now/month  "-"  d02 now/day]

print rejoin [
	pick system/locale/days now/weekday ", "
	pick system/locale/months now/month " "
	now/day ", " now/year
]
Output:
6-Dec-2009/10:02:10-5:00
2009-12-06
Sunday, December 6, 2009

RED

Red []
;; zeropad
f2n: func [d] [ if  d > 9 [return d ]   append copy "0" d  ]

d: now/date

print rejoin [d/year "-" f2n d/month "-" f2n d/day]
print rejoin [system/locale/days/(d/weekday) ", " system/locale/months/(d/month) " " f2n d/day ", " d/year]
Output:
2020-03-25

Wednesday, March 25, 2020

REXX

REXX has a number of ways to obtain the various components of the current date (indeed, any date).
It's up to the programmer to choose whatever version of the   date   BIF that best serves the purpose.

idiomatic version

/*REXX pgm shows current date:  yyyy-mm-dd  &  Dayofweek, Month dd, yyyy*/
   x = date('S')                       /*get current date as  yyyymmdd  */
yyyy = left(x,4)                       /*pick off year         (4 digs).*/
  dd = right(x,2)                      /*pick off day-of-month (2 digs).*/
  mm = substr(x,5,2)                   /*pick off month number (2 digs).*/
say yyyy'-'mm"-"dd                     /*yyyy-mm-dd with leading zeroes.*/

weekday = date('W')                    /*dayofweek (Monday or somesuch).*/
month   = date('M')                    /*Month     (August or somesuch).*/
zdd     = dd+0                         /*remove leading zero from  DD   */
say weekday',' month zdd"," yyyy       /*format date as:  Month dd, yyyy*/
                                       /*stick a fork in it, we're done.*/
Output:
2010-09-01
Wednesday, September 1, 2010 

compact version

/*REXX pgm shows current date:  yyyy-mm-dd  &  Dayofweek, Month dd, yyyy*/
/* ╔══════════════════════════════════════════════════════════════════╗
   ║  function              returns               a specific example  ║
   ║ ───────────   ───────────────────────────   ──────────────────── ║
   ║  date()        dd mon yyyy                      3 Jun 2009       ║
   ║  date('N')     (same as above)                                   ║
   ║  date('B')     days since Jan 1, year 1           735382         ║
   ║  date('C')     days since Jan 1 this century       5264          ║
   ║  date('D')     days since Jan 1, this yr            154          ║
   ║  date('E')     dd/mm/yy                          03/06/09        ║
   ║  date('I')     yyyy-mm-dd                       2009-03-06       ║
   ║  date('J')     yyddd                              2009154        ║
   ║  date('M')     month name                          June          ║
   ║  date('O')     yy/mm/dd                          09/03/06        ║
   ║  date('S')     yyyyddmm                          20090603        ║
   ║  date('T')     seconds since Jan 1st, 1970      1401483686       ║
   ║  date('U')     mm/dd/yy                          03/06/09        ║
   ║  date('W')     day─of─the─week                   Wednesday       ║
   ║ ───────────   ───────────────────────────   ──────────────────── ║
   ║                                                                  ║
   ║  Note:  not all of the above are supported by all REXX versions. ║
   ╚══════════════════════════════════════════════════════════════════╝ */
parse value date('S') with yyyy 5 mm 7 dd   /*get various pieces of date*/
say yyyy'-'mm"-"dd                     /*yyyy-mm-dd with leading zeroes.*/

say  date('W')","   date('M')   word(date(), 1)","   yyyy
                                       /* [↑]  dayofweek  Month dd, yyyy*/
                                       /*stick a fork in it, we're done.*/

output would be the same as the 1st version.

modern version

This version can be used with those REXXes that support the   I   (ISO) parameter for the   date   BIF.

/*REXX pgm shows current date:  yyyy-mm-dd  &  Dayofweek, Month dd, yyyy*/
say date('I')                          /*yyyy-mm-dd with leading zeroes.*/

say  date('W')","   date('M')   word(date(), 1)","  left(date('S'),4)
                                       /* [↑]  dayofweek  Month dd, yyyy*/
                                       /*stick a fork in it, we're done.*/

output would be the same as the 1st version.

Ring

dateStr = date()
date1 = timelist()[19] + "-" + timelist()[10] + "-" + timelist()[6]
date2 = timelist()[2] + ", " + timelist()[4] + " " + timelist()[6] + ", " + timelist()[19] + nl
? dateStr
? date1
? date2

/*
timelist() ---> List contains the time and date information.
Index           Value
----------------------------
1 - abbreviated weekday name
2 - full weekday name
3 - abbreviated month name
4 - full month name
5 - Date & Time
6 - Day of the month
7 - Hour (24)
8 - Hour (12)
9 - Day of the year
10 - Month of the year
11 - Minutes after hour
12 - AM or PM
13 - Seconds after the hour
14 - Week of the year (sun-sat)
15 - day of the week
16 - date
17 - time
18 - year of the century
19 - year
20 - time zone
21 - percent sign
*/
Output:
19/07/2020
2020-07-19
Sunday, July 19, 2020

RPL

RPL can return the date as a floating point number (format dd.mmyyyy) and can convert it (along with the time) as a string (format "DAY dd.mm.yy hh.mm.ss") To solve the task, some formatting is then needed.

Works with: HP version 48
≪ DATE DUP 1000000 * 10000 MOD "-" +
   OVER FP 100 * IP + "-" + 
   SWAP IP +
≫ 'DTSHORT' STO

≪ { "Monday" "Tuesday" "Wednesday" "Thursday" "Friday" "Saturday" "Sunday" }
   { "MON" "TUE" "WED" "THU" "FRI" "SAT" "SUN" }
   DATE TIME TSTR 1 3 SUB POS GET ", " +
   { "January" "February" "March" "April" "May" "June" "July" "August" "September" "October" "November" "December"}
   DATE FP 100 * IP GET + " " +
   OVER IP + ", " +
   DATE 1000000 * 10000 MOD +
≫ 'DTLONG' STO
Output:
2: "2023-8-17"
1: "Thursday, August 17, 2023"

Ruby

Formatting rules: Time#strftime

puts Time.now
puts Time.now.strftime('%Y-%m-%d')
puts Time.now.strftime('%F')            # same as %Y-%m-%d (ISO 8601 date formats)
puts Time.now.strftime('%A, %B %d, %Y')
Output:
2015-02-08 10:48:45 +0900
2015-02-08
2015-02-08
Sunday, February 08, 2015

Run BASIC

'Display the current date in the formats of "2007-11-10" and "Sunday, November 10, 2007".
print date$("yyyy-mm-dd")
print date$("dddd");", ";                     'return full day of the week (eg. Wednesday
print date$("mmmm");" ";                      'return full month name (eg. March) 
print date$("dd, yyyy")                       'return day, year
Output:
2012-03-16
Friday, March 16, 2012

Rust

Using chrono 0.4.6

fn main() {
    let now = chrono::Utc::now();
    println!("{}", now.format("%Y-%m-%d"));
    println!("{}", now.format("%A, %B %d, %Y"));
}

Scala

import java.util.Date

val now=new Date()
println("%tF".format(now))
println("%1$tA, %1$tB %1$td, %1$tY".format(now))
Output:
2023-04-17
Monday, April 17, 2023

Scheme

Works with: Guile version 2.0.13
(define short-date
  (lambda (lt)
    (strftime "%Y-%m-%d" (localtime lt))))

(define long-date
  (lambda (lt)
    (strftime "%A, %B %d, %Y" (localtime lt))))

(define main
  (lambda (args)
    ;; Current date
    (let ((dt (car (gettimeofday))))
      ;; Short style
      (display (short-date dt))(newline)
      ;; Long style
      (display (long-date dt))(newline))))

Seed7

$ include "seed7_05.s7i";
  include "time.s7i";
 
const proc: main is func
  local
    const array string: months is [] ("January", "February", "March", "April", "May", "June",
        "July", "August", "September", "October", "November", "December");
    const array string: days is [] ("Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday");
    var time: now is time.value;
  begin
    now := time(NOW);
    writeln(strDate(now));
    writeln(days[dayOfWeek(now)] <& ", " <& months[now.month] <& " " <& now.day <& ", " <& now.year);
  end func;

SenseTalk

put formattedTime( "[year]-[month]-[day]", the date)

put formattedTime( "[weekday], [month name] [day], [year]", the date)
Output:
2019-12-18
Wednesday, December 18, 2019

Shiny

say time.format 'Y-m-d' time.now
say time.format 'l, F j, Y' time.now

Sidef

var time = Time.local;
say time.ctime;
say time.strftime("%Y-%m-%d");
say time.strftime("%A, %B %d, %Y");
Output:
Fri Oct 17 12:57:02 2014
2014-10-17
Friday, October 17, 2014

Smalltalk

In Smalltalk, one sends a printFormat message to a Date object with year, month, and day. For other date strings, one must construct the date string from the parts of a Date object. Of course, you'd probably want to make a method for doing so.

| d |
d := Date today.
d printFormat: #(3 2 1 $- 1 1 2).
(d weekday asString), ', ', (d monthName), ' ', (d dayOfMonth asString), ', ', (d year asString)
Works with: Smalltalk/X
d := Date today.
d printOn:Stdout format:'%y-%m-%d'. Stdout cr.
d printOn:Stdout format:'%(DayName), %(MonthName) %d, %y' language:#en. Stdout cr.
d printOn:Stdout format:'%(DayName), %(MonthName) %d, %y' language:#de. Stdout cr.
d printOn:Stdout format:'%(DayName), %(MonthName) %d, %y' language:#fr. Stdout cr.
Output:
2020-12-17
Thursday, December 17, 2020
Donnerstag, Dezember 17, 2020
Vendredi, Décembre 17, 2020

SparForte

As a structured script. Does not use l10n package.

#!/usr/local/bin/spar
pragma annotate( summary, "dateformat")
       @( description, "Display the current date in the formats of '2007-11-10' " )
       @( description, "and 'Sunday, November 10, 2007'." )
       @( see_also, "http://rosettacode.org/wiki/Date_format" )
       @( "Ken O. Burtch" );
pragma license( unrestricted );

pragma restriction( no_external_commands );

procedure dateformat is
   function Month_Image (Month : calendar.month_number) return string is
   begin
      case Month is
         when 1  => return "January";
         when 2  => return "February";
         when 3  => return "March";
         when 4  => return "April";
         when 5  => return "May";
         when 6  => return "June";
         when 7  => return "July";
         when 8  => return "August";
         when 9  => return "September";
         when 10 => return "October";
         when 11 => return "November";
         when others => return "December";
      end case;
   end Month_Image;
   function Day_Image (Day : integer) return string is
   begin
      case Day is
         when 0 => return "Monday";
         when 1 => return "Tuesday";
         when 2 => return "Wednesday";
         when 3 => return "Thursday";
         when 4 => return "Friday";
         when 5 => return "Saturday";
         when others => return "Sunday";
      end case;
   end Day_Image;
   Today : constant calendar.time := calendar.clock;
begin
   --put_line(
   --Put_Line (Image (Today) (1..10));

   put( calendar.year( Today ), "9999" ) @( "-" )
     @( calendar.month( Today ), "99" ) @( "-" )
     @( calendar.day( Today ), "99" );
   new_line;

   put_line(
        Day_Image( calendar.day_of_week( Today ) ) & ", " &
        Month_Image( calendar.month( Today ) ) &
        strings.image( calendar.day( Today ) ) & "," &
        strings.image( calendar.year( Today ) ) );
end dateformat;

SQL

Works with: Oracle
select to_char(sysdate,'YYYY-MM-DD') date_fmt_1 from dual;

select to_char(sysdate,'fmDay, Month DD, YYYY') date_fmt_2 from dual;
SQL>
DATE_FMT_1
----------
2016-12-12

SQL> SQL>
DATE_FMT_2
--------------------------------------------------------------------------------
Monday, December 12, 2016

Standard ML

Formatting rules: http://www.standardml.org/Basis/date.html#SIG:DATE.fmt:VAL

print (Date.fmt "%Y-%m-%d" (Date.fromTimeLocal (Time.now ())) ^ "\n");
print (Date.fmt "%A, %B %d, %Y" (Date.fromTimeLocal (Time.now ())) ^ "\n");
Output:
2008-02-13
Wednesday, February 13, 2008

Stata

Stata has many ways to format dates, see Datetime display formats in the documentation.

display %tdCCYY-NN-DD td($S_DATE)
display %tdDayname,_Month_dd,_CCYY td($S_DATE)

Suneido

Date().Format('yyyy-MM-dd')  -->  "2010-03-16"
Date().LongDate() -->  "Tuesday, March 16, 2010"

Swift

import Foundation
extension String {
    func toStandardDateWithDateFormat(format: String) -> String {
        let dateFormatter = NSDateFormatter()
        dateFormatter.dateFormat = format
        dateFormatter.dateStyle = .LongStyle
        return dateFormatter.stringFromDate(dateFormatter.dateFromString(self)!)
    }
}

let date = "2015-08-28".toStandardDateWithDateFormat("yyyy-MM-dd")
Output:
2015ꈎ8ꆪ28ꑍ(In Sichuan Yi Language Environment)

Tcl

set now [clock seconds]
puts [clock format $now -format "%Y-%m-%d"]
puts [clock format $now -format "%A, %B %d, %Y"]

Terraform

locals {
  today = timestamp()
}

output "iso" {
  value = formatdate("YYYY-MM-DD", local.today)
}

output "us-long" {
  value = formatdate("EEEE, MMMM D, YYYY", local.today)
}
Output:
Apply complete! Resources: 0 added, 0 changed, 0 destroyed.

Outputs:

iso = 2020-09-16
us-long = Wednesday, September 16, 2020

TUSCRIPT

$$ MODE TUSCRIPT
SET dayofweek = DATE (today,day,month,year,number)

SET months=*
DATA January
DATA Februari
DATA March
DATA April
DATA Mai
DATA June
DATA July
DATA August
DATA September
DATA October
DATA November
DATA December

SET days="Monday'Tuesday'Wendsday'Thursday'Fryday'Saturday'Sonday"

SET nameofday  =SELECT (days,#dayofweek)
SET nameofmonth=SELECT (months,#month)

SET format1=JOIN (year,"-",month,day)
SET format2=CONCAT (nameofday,", ",nameofmonth," ",day, ", ",year)

PRINT format1
PRINT format2
Output:
2011-1-5
Wendsday, January 5, 2011

UNIX Shell

date +"%Y-%m-%d"
date +"%A, %B %d, %Y"

On a new enough system %F is equivalent to %Y-%m-%d

date +"%F"


Ursa

Works with: Cygnus/X Ursa

Cygnus/X Ursa can import and call Java classes.

cygnus/x ursa v0.78 (default, release 0)
[Oracle Corporation JVM 1.8.0_51 on Mac OS X 10.10.5 x86_64]
> import "java.util.Date"
> import "java.text.SimpleDateFormat"
> decl java.text.SimpleDateFormat sdf
> sdf.applyPattern "yyyy-MM-dd"
> decl java.util.Date d
> out (sdf.format d) endl console
2016-07-23
> sdf.applyPattern "EEEE, MMMM dd, yyyy"
> out (sdf.format d) endl console
Saturday, July 23, 2016
> _

Ursala

The method is to transform a date in standard format returned by the library function, now.

#import std
#import cli

months = ~&p/block3'JanFebMarAprMayJunJulAugSepOctNovDec' block2'010203040506070809101112'

completion =

-:~& ~&pllrTXS/block3'SunMonTueWedThuFriSat'--(~&lS months) -- (
   --','* sep`, 'day,day,sday,nesday,rsday,day,urday',
   sep`, 'uary,ruary,ch,il,,e,y,ust,tember,ober,ember,ember')

text_form    = sep` ; mat` + completion*+ <.~&hy,~&tth,--','@th,~&ttth>
numeric_form = sep` ; mat`-+ <.~&ttth,@tth -: months,~&th>

#show+

main = <.text_form,numeric_form> now0
Output:
Wednesday, June 24, 2009
2009-06-24

VB-DOS

OPTION EXPLICIT

' Months
DATA "January", "February", "March", "April", "May", "June", "July"
DATA "August", "September", "October", "November", "December"

' Days of week
DATA "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"

' Var
DIM dDate AS DOUBLE, sMonth(1 TO 12) AS STRING, sDay(1 TO 7) AS STRING
DIM i AS INTEGER

' Read Names of months
FOR i = 1 TO 12
  READ sMonth(i)
NEXT i

' Read Names of days
FOR i = 1 TO 7
  READ sDay(i)
NEXT i

' Assign current date to a variable
dDate = NOW

CLS
PRINT "Rosettacode: Display the current date formatted."
PRINT
PRINT "Today's date: "; FORMAT$(dDate, "ddddd")
PRINT
PRINT "Use of values in the lists."
PRINT "Today is "; sDay(WEEKDAY(dDate)); ", "; sMonth(MONTH(dDate)); " "; FORMAT$(DAY(dDate)); ", "; FORMAT$(YEAR(dDate)); "."
PRINT
PRINT "Use of just the FORMAT$() function."
PRINT "Today is "; FORMAT$(dDate, "dddd, mmmm d, yyyy"); "."

END

VBA

Function DateFormats()
    Debug.Print Format(Date, "yyyy-mm-dd")
    Debug.Print Format(Date, "dddd, mmmm dd yyyy")
End Function

VBScript

'YYYY-MM-DD format
WScript.StdOut.WriteLine Year(Date) & "-" & Right("0" & Month(Date),2) & "-" & Right("0" & Day(Date),2)

'Weekday_Name, Month_Name DD, YYYY format
WScript.StdOut.WriteLine FormatDateTime(Now,1)
Output:
2015-08-31
Monday, August 31, 2015

Vedit macro language

Display current date in format "2007-11-10":

Date(REVERSE+NOMSG+VALUE, '-')

Display current date in format "Sunday, November 10, 2007" (Requires VEDIT 6.2):

// Get todays date into #1, #2, #3 and #7
#1 = Date_Day
#2 = Date_Month
#3 = Date_Year
#7 = JDate() % 7              // #7 = weekday

// Convert weekday number (in #7) into word in T-reg 1
if (#7==0) { RS(1,"Sunday") }
if (#7==1) { RS(1,"Monday") }
if (#7==2) { RS(1,"Tuesday") }
if (#7==3) { RS(1,"Wednesday") }
if (#7==4) { RS(1,"Thursday") }
if (#7==5) { RS(1,"Friday") }
if (#7==6) { RS(1,"Saturday") }

// Convert month number (in #2) into word in T-reg 2
if (#2==1)  { RS(2,"January") }
if (#2==2)  { RS(2,"February") }
if (#2==3)  { RS(2,"March") }
if (#2==4)  { RS(2,"April") }
if (#2==5)  { RS(2,"May") }
if (#2==6)  { RS(2,"June") }
if (#2==7)  { RS(2,"July") }
if (#2==8)  { RS(2,"August") }
if (#2==9)  { RS(2,"September") }
if (#2==10) { RS(2,"October") }
if (#2==11) { RS(2,"November") }
if (#2==12) { RS(2,"December") }

// Display the date string
RT(1) M(", ") RT(2) M(" ") NT(#1, LEFT+NOCR) M(",") NT(#3)

To insert the date string into edit buffer instead of displaying it, replace the last line with this:

RI(1) IT(", ") RI(2) IT(" ") NI(#1, LEFT+NOCR) IT(",") NI(#3)

Vim Script

See `:help strftime` - this function uses the C strftime() arguments' format.

echo strftime("%Y-%m-%d")
echo strftime("%A, %B %d, %Y")

V (Vlang)

import time

fn main() {
    println(time.now().custom_format("YYYY-MM-DD"))
    println(time.now().custom_format("dddd, MMMM D, YYYY"))
}
Output:
2011-12-02
Friday, December 2, 2011

Wren

Library: Wren-date

Unless it is embedded in a host application, Wren currently has no direct way to obtain the current date. We therefore assume this is passed in by the user as a command line parameter.

import "os" for Process
import "./date" for Date

var args = Process.arguments
if (args.count != 1) {
    Fiber.abort("Please pass just the current date in yyyy-mm-dd format.")
}
var current = Date.parse(args[0])
System.print(current.format(Date.isoDate))
System.print(current.format("dddd|, |mmmm| |d|, |yyyy"))
Output:
$ wren date_format.wren 2020-06-05
2020-06-05
Friday, June 5, 2020

XPL0

include c:\cxpl\codes;
int CpuReg, Year, Month, Day, DName, MName, WDay;
[CpuReg:= GetReg;       \access CPU registers
CpuReg(0):= $2A00;      \DOS system call
SoftInt($21);
Year:= CpuReg(2);
Month:= CpuReg(3) >> 8;
Day:= CpuReg(3) & $FF;
WDay:= CpuReg(0) & $FF;
IntOut(0, Year);  ChOut(0, ^-);
if Month<10 then ChOut(0, ^0);  IntOut(0, Month);  ChOut(0, ^-);
if Day<10 then ChOut(0, ^0);  IntOut(0, Day);  CrLf(0);
DName:= ["Sunday", "Monday", "Tuesday", "Wednesday",
        "Thursday", "Friday", "Saturday"];
MName:= [0, "January", "February", "March", "April", "May", "June", "July",
        "August", "September", "October", "November", "December"];
Text(0, DName(WDay));  Text(0, ", ");  Text(0, MName(Month));  Text(0, " ");
IntOut(0, Day);  Text(0, ", ");  IntOut(0, Year);  CrLf(0);
]
Output:
2012-11-20
Tuesday, November 20, 2012

Yabasic

dim n$(1)

n = token(date$, n$(), "-")

print n$(4), "-", n$(2), "-", n$(3)
print nDay$(n$(5)), ", ", nMonth$(n$(6)), " ", n$(3), ", ", n$(4)

sub nDay$(n$)
	switch n$
	case "Mon": case "Fri": case "Sun": break
	case "Tue": n$ = n$ + "s" : break
	case "Wed": n$ = n$ + "nes" : break
	case "Thu": n$ = n$ + "rs" : break
	case "Sat": n$ = n$ + "ur" : break
	default: n$ = "none" : break
	end switch
	
	return n$ + "day"
end sub

sub nMonth$(n$)
	local month$(1), n
	
	n = token("January, February, March, April, May, June, July, August, September, October, November, December", month$(), ", ")
	n = instr("JanFebMarAprMayJunJulAugSepOctNovDec", n$)
	
	return month$(int(n/3) + 1)
end sub

zkl

"%d-%02d-%02d".fmt(Time.Clock.localTime.xplode()).println()
//--> "2014-02-28" (ISO format)

Not quite but close. Even though localTime returns a 7 tuple (and xplode pushes all 7 as call args), fmt only eats what it needs.

Time.Date.prettyDay(Time.Clock.localTime.xplode())
//--> "Friday, the 28th of February 2014"
y,m,d:=Time.Clock.localTime; D:=Time.Date;
"%s, %s %d, %d".fmt(D.dayName(D.weekDay(y,m,d)),
                    D.monthName(m), d,y)
//-->"Friday, February 28, 2014"

zonnon

module Main;
import System;

var
	now: System.DateTime;
begin
	now := System.DateTime.Now;
	System.Console.WriteLine(now.ToString("yyyy-MM-dd");
	System.Console.WriteLine("{0}, {1}",now.DayOfWeek,now.ToString("MMMM dd, yyyy"));
end Main.
Output:
2017-12-05
Tuesday, diciembre 05, 2017