# Day of the week

Day of the week
You are encouraged to solve this task according to the task description, using any language you may know.

A company decides that whenever Xmas falls on a Sunday they will give their workers all extra paid holidays so that, together with any public holidays, workers will not have to work the following week (between the 25th of December and the first of January).

In what years between 2008 and 2121 will the 25th of December be a Sunday?

Using any standard date handling libraries of your programming language; compare the dates calculated with the output of other languages to discover any anomalies in the handling of dates which may be due to, for example, overflow in types used to represent dates/times similar to   y2k   type problems.

## 11l

`print((2008..2121).filter(y -> Time(y, 12, 25).strftime(‘%w’) == ‘0’))`
Output:
```[2011, 2016, 2022, 2033, 2039, 2044, 2050, 2061, 2067, 2072, 2078, 2089, 2095, 2101, 2107, 2112, 2118]
```

## 360 Assembly

Translation of: REXX

The program uses two ASSIST macro (XDECO,XPRNT) to keep the code as short as possible.

```*        Day of the week           06/07/2016
DOW      CSECT
USING  DOW,R15            base register
LA     R6,2008            year=2008
LOOP     C      R6,=F'2121'        do year=2008 to 2121
BH     ELOOP              .
LR     R7,R6              y=year
LA     R8,12              m=12
LA     R9,25              d=25
C      R8,=F'3'           if m<3
BNL    MGE3               then
LA     R8,12(R8)            m=m+12
BCTR   R7,0                 y=y-1
MGE3     LR     R10,R7             y
SRDA   R10,32             .
D      R10,=F'100'        r=y//100 ; l=y/100
LR     R3,R8              m
LA     R3,1(R3)           m+1
M      R2,=F'26'          *26
D      R2,=F'10'          /10
AR     R3,R9              +d
AR     R3,R10             +r
LR     R2,R10             r
SRA    R2,2               /4
AR     R2,R3              (d+(m+1)*26/10+r+r/4
LR     R3,R11             l
SRA    R3,2               /4
AR     R2,R3              (d+(m+1)*26/10+r+r/4+l/4
LA     R5,5               5
MR     R4,R11             *l
AR     R2,R5              (d+(m+1)*26/10+r+r/4+l/4+5*l)
SRDA   R2,32              .
D      R2,=F'7'           w=(d+(m+1)*26/10+r+r/4+l/4+5*l)//7
C      R2,=F'1'           if w=1  (sunday)
BNE    WNE1               then
XDECO  R6,PG                edit year
XPRNT  PG,12                print year
WNE1     LA     R6,1(R6)           year=year+1
B      LOOP               next year
ELOOP    BR     R14                exit
PG       DS     CL12               buffer
YREGS
END    DOW```
Output:
```        2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118```

## ABAP

```report zday_of_week
data: lv_start type i value 2007,
lv_n type i value 114,
lv_date type sy-datum,
lv_weekday type string,
lv_day type c,
lv_year type n length 4.

write 'December 25 is a Sunday in: '.
do lv_n times.
lv_year = lv_start + sy-index.
concatenate lv_year '12' '25' into lv_date.
call function 'DATE_COMPUTE_DAY'
exporting date = lv_date
importing day  = lv_day.

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

if lv_weekday eq 'Sunday'.
write / lv_year.
endif.
enddo.
```
Output:
```December 25 is a Sunday in:
2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
```

## Action!

Action! does not have a standard library providing a day of week function, therefore an adaptation of Sakamoto's method to determine the day of week for a given date using integer arithmetic is used.

```Byte FUNC DayOfWeek(BYTE day, month CARD year BYTE century)
CARD weekday
BYTE ARRAY index=[0 3 2 5 0 3 5 1 4 6 2 4]

IF year < 100  THEN
year = year + century * 100
FI

IF year < 1753 THEN RETURN(7) FI

IF month < 3 THEN
year==-1
FI

month = index(month-1)
weekday=year + year/4 - year/100 + year/400 + month + day
weekday = weekday MOD 7
RETURN (weekday)

PROC main()
CARD y
PrintE("December 25 is a Sunday in:")
FOR y = 2008 to 2121
DO
IF DayOfWeek(25, 12, y)=0 THEN
PrintCE(y)
FI
OD
RETURN```
Output:
```December 25 is a Sunday in:
2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
```

```with Ada.Calendar.Formatting;  use Ada.Calendar.Formatting;

procedure Yuletide is
begin
for Year in 2008..2121 loop
if Day_Of_Week (Time_Of (Year, 12, 25)) = Sunday then
Put_Line (Image (Time_Of (Year, 12, 25)));
end if;
end loop;
end Yuletide;
```
Output:
```2011-12-25 00:00:00
2016-12-25 00:00:00
2022-12-25 00:00:00
2033-12-25 00:00:00
2039-12-25 00:00:00
2044-12-25 00:00:00
2050-12-25 00:00:00
2061-12-25 00:00:00
2067-12-25 00:00:00
2072-12-25 00:00:00
2078-12-25 00:00:00
2089-12-25 00:00:00
2095-12-25 00:00:00
2101-12-25 00:00:00
2107-12-25 00:00:00
2112-12-25 00:00:00
2118-12-25 00:00:00
```

## ALGOL 68

Works with: ALGOL 68 version Revision 1 - no extensions to language used
Works with: ALGOL 68G version Any - tested with release 1.18.0-9h.tiny
Works with: ELLA ALGOL 68 version Any (with appropriate job cards) - tested with release 1.8-8d
```# example from: http://www.xs4all.nl/~jmvdveer/algol.html - GPL #
INT sun=0 # , mon=1, tue=2, wed=3, thu=4, fri=5, sat=6 #;

PROC day of week = (INT year, month, day) INT: (
# Day of the week by Zeller’s Congruence algorithm from 1887 #
INT y := year, m := month, d := day, c;
IF m <= 2 THEN
m +:= 12; y -:= 1
FI;
c := y OVER 100;
y %*:= 100;
(d - 1 + ((m + 1) * 26) OVER 10 + y + y OVER 4 + c OVER 4 - 2 * c) MOD 7
);

test:(
print("December 25th is a Sunday in:");
FOR year FROM 2008 TO 2121 DO
INT wd = day of week(year, 12, 25);
IF wd = sun THEN print(whole(year,-5)) FI
OD;
new line(stand out)
)```
Output:
```December 25th is a Sunday in: 2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2101 2107 2112 2118
```

## ALGOL W

Translation of: Fortran
```begin % find years where Christmas day falls on a Sunday %
integer procedure Day_of_week ( integer value d, m, y );
begin
integer j, k, mm, yy;
mm := m;
yy := y;
if mm <= 2 then begin
mm := mm + 12;
yy := yy - 1;
end if_m_le_2;
j := yy div 100;
k := yy rem 100;
(d + ( ( mm + 1 ) * 26 ) div 10 + k + k div 4 + j div 4 + 5 * j ) rem 7
end Day_of_week;
write( "25th of December is a Sunday in" );
for year := 2008 until 2121 do begin
integer day;
day := Day_of_week( 25, 12, year );
if day = 1 then writeon( I_W := 5, S_W := 0, year );
end for_year
end.```
Output:
```25th of December is a Sunday in 2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2101 2107 2112 2118
```

## ALGOL-M

```BEGIN

% CALCULATE P MOD Q %
INTEGER FUNCTION MOD(P, Q);
INTEGER P, Q;
BEGIN
MOD := P - Q * (P / Q);
END;

COMMENT
RETURN DAY OF WEEK (SUN=0, MON=1, ETC.) FOR A GIVEN
GREGORIAN CALENDAR DATE USING ZELLER'S CONGRUENCE;
INTEGER FUNCTION DAYOFWEEK(MO, DA, YR);
INTEGER MO, DA, YR;
BEGIN
INTEGER Y, C, Z;
IF MO < 3 THEN
BEGIN
MO := MO + 10;
YR := YR - 1;
END
ELSE MO := MO - 2;
Y := MOD(YR, 100);
C := YR / 100;
Z := (26 * MO - 2) / 10;
Z := Z + DA + Y + (Y / 4) + (C /4) - 2 * C + 777;
DAYOFWEEK := MOD(Z, 7);
END;

% MAIN PROGRAM STARTS HERE %
INTEGER YEAR, SUNDAY;
SUNDAY := 0;
WRITE("CHRISTMAS WILL FALL ON A SUNDAY IN THESE YEARS:");
FOR YEAR := 2008 STEP 1 UNTIL 2121 DO
BEGIN
IF DAYOFWEEK(12, 25, YEAR) = SUNDAY THEN
WRITE(YEAR);
END;

END```
Output:
```CHRISTMAS WILL FALL ON A SUNDAY IN THESE YEARS:
2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
```

## APL

```⍝ Based on the simplified calculation of Zeller's congruence, since Christmas is after March 1st, no adjustment is required.
⎕IO ← 0              ⍝ Indices are 0-based
y ← 2008 + ⍳114      ⍝ Years from 2008 to 2121
⍝ Simplified Zeller function operating on table of dates formatted as 114 rows and 3 columns of (day, month, year)
⍝ 0 = Saturday, 1 = Sunday, 2 = Monday, 3 = Tuesday, 4 = Wednesday, 5 = Thursday, 6 = Friday
zeller ← { 7 | +/ (((1↑⍴⍵),6)⍴1 1 1 1 ¯1 1) × ⌊(((⍴⍵)⍴1 13 1)×⍵+(⍴⍵)⍴0 1 0)[;0 1 2 2 2 2]÷((1↑⍴⍵),6)⍴1 5 1 4 100 400 }
result ← (1 = zeller 25,[1]12,[0.5]y) / y
```
Output:
```  result
2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2101 2107 2112 2118
```

## AppleScript

```set ChristmasSundays to {}
set Christmas to (current date)
set month of Christmas to December
set day of Christmas to 25
repeat with |year| from 2008 to 2121
set year of Christmas to |year|
if weekday of Christmas is Sunday then set end of ChristmasSundays to |year|
end repeat
ChristmasSundays
```

Or, composing generic functions:

```-- xmasIsSunday :: Int -> Bool
on xmasIsSunday(y)
tell (current date)
set {its year, its month, its day, its time} to {y, 12, 25, 0}
its weekday is Sunday
end tell
end xmasIsSunday

-------------------------- TEST ---------------------------
on run

filter(xmasIsSunday, enumFromTo(2008, 2121))

end run

-------------------- GENERIC FUNCTIONS --------------------

-- enumFromTo :: Int -> Int -> [Int]
on enumFromTo(m, n)
if m ≤ n then
set lst to {}
repeat with i from m to n
set end of lst to i
end repeat
lst
else
{}
end if
end enumFromTo

-- filter :: (a -> Bool) -> [a] -> [a]
on filter(f, xs)
tell mReturn(f)
set lst to {}
set lng to length of xs
repeat with i from 1 to lng
set v to item i of xs
if |λ|(v, i, xs) then set end of lst to v
end repeat
return lst
end tell
end filter

-- Lift 2nd class handler function into 1st class script wrapper
-- mReturn :: Handler -> Script
on mReturn(f)
if class of f is script then
f
else
script
property |λ| : f
end script
end if
end mReturn
```
Output:
```{2011, 2016, 2022, 2033, 2039, 2044, 2050, 2061, 2067,
2072, 2078, 2089, 2095, 2101, 2107, 2112, 2118}
```

## Arc

```(= day-names '(Sunday Monday Tuesday Wednesday Thursday Friday Saturday))
(= get-weekday-num (fn (year month day)
(= helper '(0 3 2 5 0 3 5 1 4 6 2 4))
(if (< month 3) (= year (- year 1)))
(mod (+ year (helper (- month 1)) day
(apply + (map [trunc (/ year _)] '(4 -100 400))))
7)))
(= get-weekday-name (fn (weekday-num) (day-names weekday-num)))```

test:

```(up i 2008 2121
(when (is 0 (get-weekday-num i 12 25))
(prn i)))

2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118```

## Arturo

```print select 2008..2121 'year [
"Sunday" = get to :date.format:"dd-MM-YYYY" ~"25-12-|year|" 'Day
]
```
Output:
`2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2101 2107 2112 2118 `

## AutoHotkey

```year = 2008
stop = 2121

While year <= stop {
FormatTime, day,% year 1225, dddd
If day = Sunday
out .= year "`n"
year++
}
MsgBox,% out
```

## AutoIt

```#include <date.au3>
Const \$iSunday = 1
For \$iYear = 2008 To 2121 Step 1
If \$iSunday = _DateToDayOfWeek(\$iYear, 12, 25) Then
ConsoleWrite(StringFormat(\$iYear & "\n"))
EndIf
Next
```

## AWK

```# syntax: GAWK -f DAY_OF_THE_WEEK.AWK
# runtime does not support years > 2037 on my 32-bit Windows XP O/S
BEGIN {
for (i=2008; i<=2121; i++) {
x = strftime("%Y/%m/%d %a",mktime(sprintf("%d 12 25 0 0 0",i)))
if (x ~ /Sun/) { print(x) }
}
}
```

## BASIC

### Applesoft BASIC

Translation of: Commodore BASIC
``` 1  DEF  FN D7(N) = N - 7 *  INT (N / 7)
2  DEF  FN RD(Y) = 365 * Y +  INT (Y / 4) -  INT (Y / 100) +  INT (Y / 400)
3  PRINT "YEARS WITH CHRISTMAS ON A SUNDAY" CHR\$ (13)
4  FOR Y = 2008 TO 2121
5      IF  NOT  FN D7( FN RD(Y) - 6) THEN  PRINT Y,
6  NEXT Y```

### ASIC

Translation of: GW-BASIC
```REM Day of the week
Month = 12
Day = 25
FOR Year = 2007 TO 2122
GOSUB CalcDayOfWeek:
IF DayOfWeek = 0 THEN
PRINT Year;
ENDIF
NEXT Year
PRINT
END

CalcDayOfWeek:
REM Sunday = 0, Saturday = 6
IF Month < 3 THEN
Year = Year - 1
Month = Month + 12
ENDIF
DayOfWeek = Year
YearDiv = Year / 4
DayOfWeek = DayOfWeek + YearDiv
YearDiv = Year / 100
DayOfWeek = DayOfWeek - YearDiv
YearDiv = Year / 400
DayOfWeek = DayOfWeek + YearDiv
DayPlus = 153 * Month
DayPlus = DayPlus + 8
DayPlus = DayPlus / 5
DayOfWeek = DayOfWeek + Day
DayOfWeek = DayOfWeek + DayPlus
DayOfWeek = DayOfWeek MOD 7
RETURN
```
Output:
```  2011  2016  2022  2033  2039  2044  2050  2061  2067  2072  2078  2089  2095  2101  2107  2112  2118
```

### Atari BASIC

Translation of: Commodore BASIC
```100 REM FIND YEARS WITH SUNDAY CHRISTMAS
110 PRINT CHR\$(125);"SUNDAY CHRISTMASES 2008-2121:":PRINT
120 FOR Y=2008 TO 2121
130 EOY=Y*365+INT(Y/4)-INT(Y/100)+INT(Y/400)
140 XMAS=EOY-6
150 DOW=XMAS-7*INT(XMAS/7)
160 IF DOW THEN 220
170 PRINT Y;
180 FOUND=FOUND+1
190 IF FOUND<3 THEN PRINT ,:GOTO 220
200 FOUND=0
210 PRINT
220 NEXT Y
230 IF FOUND THEN PRINT
```
Output:
```  SUNDAY CHRISTMASES 2008-2121

2011          2016          2022
2033          2039          2044
2050          2061          2067
2072          2078          2089
2095          2101          2107
2112          2118```

### BaCon

```' Sunday Christmas
PRINT "Years with Christmas on a Sunday"
FOR y = 2008 TO 2121
tv = TIMEVALUE(y, 12, 25, 0, 0, 0)
IF WEEKDAY\$(tv) = "Sunday" THEN PRINT y
NEXT```
Output:
```prompt\$ ./sunday-christmas
Years with Christmas on a Sunday
2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118```

### BASIC256

```for yr = 2008 to 2121
if wd(12, 25, yr) = 0 then print "Dec 25 "; yr
next
end

function wd(m, d, y)
if m < 3 then	# if m = 1 or m = 2 then
m += 12
y -= 1
end if
return (y + (y \ 4) - (y \ 100) + (y \ 400) + d + ((153 * m + 8) \ 5)) % 7
end function```
Output:
`Same as FreeBASIC entry.`

### BBC BASIC

```      INSTALL @lib\$+"DATELIB"

FOR year% = 2008 TO 2121
IF FN_dow(FN_mjd(25, 12, year%)) = 0 THEN
PRINT "Christmas Day is a Sunday in "; year%
ENDIF
NEXT
```

### Chipmunk Basic

Works with: Chipmunk Basic version 3.6.4
Translation of: Applesoft BASIC
```10 CLS : REM  10 HOME for Applesoft BASIC
20 DEF fnd7(n) = n - 7 * INT (n / 7)
30 DEF fnrd(y) = 365 * y + INT (y / 4) - INT (y / 100) + INT (y / 400)
40 PRINT "YEARS WITH CHRISTMAS ON A SUNDAY" CHR\$(13)
50 FOR y = 2008 TO 2121
60     IF NOT fn d7(fn rd(y)-6) THEN PRINT y,
70 NEXT y
```
Output:
```YEARS WITH CHRISTMAS ON A SUNDAY
2011    2016    2022    2033    2039    2044    2050    2061    2067    2072    2078    2089    2095    2101    2107   2112     2118    ```

### Commodore BASIC

This takes advantage of the dynamic scope of arguments to DEF FN functions to nest definitions and ultimately turn the question "Does Christmas fall on a Sunday in year Y?" into a single Boolean function of the year number. It's easy to run afoul of stack limitations in Microsoft BASICs doing this, especially on older versions that just use the processor's 256-byte stack instead of giving BASIC its own, but this program runs fine even on an unexpanded VIC-20.

```100 REM FIND OUT WHAT YEARS HAVE CHRISTMAS ON A SUNDAY
110 REM MODULO FUNCTION (USES CALLER'S N AS DIVIDEND)
120 DEF FNNM(D) = N - D * INT(N/D)
130 REM RATA DIE OF 31 DEC Y (CAN BE TAKEN MODULO 7 TO GET DAY OF WEEK)
140 DEF FNRD(Y) = 365 * Y + INT(Y/4) - INT(Y/100) + INT(Y/400)
150 REM TRUE IF THE GIVEN RD IS A SUNDAY
160 DEF FND7(N) = 0 = FNNM(7)
170 REM TRUE IF CHRISTMAS FALLS ON A SUNDAY IN THE GIVEN YEAR
180 DEF FNXS(Y) = FND7(FNRD(Y) - 6):REM 6 DAYS BEFORE THE END OF THE YEAR
190 REM TRY OUR TARGET YEARS AND OUTPUT THE ONES THAT MATCH
200 Y1 = 2008: Y2 = 2121
210 PRINT CHR\$(147);"CHRISTMASES ON SUNDAY";Y1;"-";Y2;CHR\$(13)
220 FOR Y=Y1 TO Y2
230 : IF FNXS(Y) THEN PRINT Y,:REM PRINT YEARS IN COLUMNS
240 NEXT Y
250 PRINT
```
Output:
```CHRISTMASES ON SUNDAY 2008 - 2121:

2011      2016      2022      2033
2039      2044      2050      2061
2067      2072      2078      2089
2095      2101      2107      2112
2118```

### FBSL

```#APPTYPE CONSOLE

'In what years between 2008 and 2121 will the 25th of December be a Sunday?
dim date as integer, dayname as string
for dim year = 2008 to 2121
date = year * 10000 + 1225
dayname = dateconv(date,"dddd")
if dayname = "Sunday" then
print "Christmas Day is on a Sunday in ", year
end if
next
PAUSE
```

### FreeBASIC

```' version 17-06-2015
' compile with: fbc -s console

Function wd(m As Integer, d As Integer, y As Integer) As Integer
If m < 3 Then        ' If m = 1 Or m = 2 Then
m += 12
y -= 1
End If
Return (y + (y \ 4) - (y \ 100) + (y \ 400) + d + ((153 * m + 8) \ 5)) Mod 7
End Function

' ------=< MAIN >=------

For yr As Integer = 2008 To 2121
If wd(12, 25, yr) = 0 Then
Print "Dec 25 "; yr
EndIf
Next

' empty keyboard buffer
While InKey <> "" : Wend
Print : Print "hit any key to end program"
Sleep
End```
Output:
```Dec 25  2011
Dec 25  2016
Dec 25  2022
Dec 25  2033
Dec 25  2039
Dec 25  2044
Dec 25  2050
Dec 25  2061
Dec 25  2067
Dec 25  2072
Dec 25  2078
Dec 25  2089
Dec 25  2095
Dec 25  2101
Dec 25  2107
Dec 25  2112
Dec 25  2118```
```Declare Function modulo(x As Double, y As Double) As Double
Declare Function wd(m As Double, d As Double, y As Double) As Integer

Cls
Dim yr As Double
For yr = 2008 To 2121
If wd(12,25,yr) = 1 Then
Print "Dec " & 25 & ", " & yr
EndIf
Next
Sleep

Function modulo(x As Double, y As Double) As Double
If y = 0 Then
Return x
Else
Return x - y * Int(x / y)
End If
End Function

Function wd(m As Double, d As Double, y As Double) As Integer
If m = 1 Or m = 2 Then
m += 12
y-= 1
End If
Return modulo(365 * y + Fix(y / 4) - Fix(y / 100) + Fix(y / 400) + d  + Fix((153 * m + 8) / 5), 7) + 1
End Function
```
Output:
```Dec 25, 2011
Dec 25, 2016
Dec 25, 2022
Dec 25, 2033
Dec 25, 2039
Dec 25, 2044
Dec 25, 2050
Dec 25, 2061
Dec 25, 2067
Dec 25, 2072
Dec 25, 2078
Dec 25, 2089
Dec 25, 2095
Dec 25, 2101
Dec 25, 2107
Dec 25, 2112
Dec 25, 2118
```
```' version 17-06-2015
' Weekday And DateSerial only works with #Include "vbcompat.bi"
' compile with: fbc -s console

#Include Once "vbcompat.bi"
Dim As Double a

For yr As Integer = 2008 To 2121
a = DateSerial (yr, 12, 25)
If Weekday(a) = 1 Then Print Format(a, "dd-mm-yyyy")   ' 1 = sunday, 2 = monday ...
Next

' empty keyboard buffer
While InKey <> "" : Wend
Print : Print "hit any key to end program"
Sleep
End```
Output:
```25-12-2011
25-12-2016
25-12-2022
25-12-2033
25-12-2039
25-12-2044
25-12-2050
25-12-2061
25-12-2067
25-12-2072
25-12-2078
25-12-2089
25-12-2095
25-12-2101
25-12-2107
25-12-2112
25-12-2118```

### FutureBasic

```window 1

long              y
CFDateRef         dt
NSInteger         day
CFCalendarRef     cal
DateComponentsRef comps

cal = fn CalendarCurrent

comps = fn DateComponentsInit
DateComponentsSetMonth( comps, 12 )
DateComponentsSetDay( comps, 25 )

for y = 2008 to 2121
DateComponentsSetYear( comps, y )
dt = fn CalendarDateFromComponents( cal, comps )
day = fn CalendarComponentFromDate( cal, NSCalendarUnitWeekday, dt )
if ( day == 1 )
print y
end if
next

HandleEvents```

### Gambas

```Public Sub Main()
Dim siCount As Short

For siCount = 2008 To 2121
If WeekDay(Date(siCount, 12, 25)) = 0 Then Print Format(Date(siCount, 12, 25), "dddd dd mmmm yyyy") & " falls on a Sunday"
Next

End```

Output:

```Sunday 25 December 2011 falls on a Sunday
Sunday 25 December 2016 falls on a Sunday
Sunday 25 December 2022 falls on a Sunday
Sunday 25 December 2033 falls on a Sunday
Sunday 25 December 2039 falls on a Sunday
Sunday 25 December 2044 falls on a Sunday
Sunday 25 December 2050 falls on a Sunday
Sunday 25 December 2061 falls on a Sunday
Sunday 25 December 2067 falls on a Sunday
Sunday 25 December 2072 falls on a Sunday
Sunday 25 December 2078 falls on a Sunday
Sunday 25 December 2089 falls on a Sunday
Sunday 25 December 2095 falls on a Sunday
Sunday 25 December 2101 falls on a Sunday
Sunday 25 December 2107 falls on a Sunday
Sunday 25 December 2112 falls on a Sunday
Sunday 25 December 2118 falls on a Sunday
```

### GW-BASIC

Works with: BASICA
```10 REM Day of the week
20 DEFINT D, M, Y-Z
30 M = 12: D = 25
40 FOR Y = 2007 TO 2122
50  GOSUB 200
60  IF Z = 0 THEN PRINT Y;
70 NEXT Y
80 PRINT
90 END
170 REM Calculate day of week Z given
180 REM year Y, month M, and day D
190 REM Sunday = 0, Saturday = 6
200 IF M < 3 THEN Y = Y - 1: M = M + 12
210 Z = Y + Y \ 4 - Y \ 100 + Y \ 400
220 Z = Z + D + (153 * M + 8) \ 5
230 Z = Z MOD 7
240 RETURN```
Output:
``` 2011  2016  2022  2033  2039  2044  2050  2061  2067  2072  2078  2089  2095  2101  2107  2112  2118
```

### IS-BASIC

```100 PROGRAM "Dayweek.bas"
110 PRINT "The years between 2008 and 2121 will the 25th of December be a Sunday:"
120 FOR Y=2008 TO 2121
130   IF DAYWEEK(Y,12,25)=0 THEN PRINT "Dec 25,";Y
140 NEXT
150 DEF DAYWEEK(Y,M,D)
160   LET A=INT((14-M)/12):LET Y=Y-A
170   LET W=D+INT((13*(M+12*A-2)-1)/5)+Y+INT(Y/4)-INT(Y/100)+INT(Y/400)
180   LET DAYWEEK=W-7*INT(W/7)
190 END DEF```

### Liberty BASIC

Works with: Just BASIC
```count = 0
for year = 2008 to 2121
dateString\$="12/25/";year
dayNumber=date\$(dateString\$)
if dayNumber mod 7 = 5 then
count = count + 1
print dateString\$
end if
next year
print count; " years when Christmas Day falls on a Sunday"
end```

### Minimal BASIC

Works with: IS-BASIC
```10 REM Find years with Sunday Christmas
20 LET F = 2008
30 LET T = 2121
40 PRINT "Sunday Christmases"; F; "-"; T
50 PRINT
60 FOR Y = F TO T
70 LET E = Y*365+INT(Y/4)-INT(Y/100)+INT(Y/400)
80 LET X = E-6
90 LET D = X-7*INT(X/7)
100 IF D <> 0 THEN 120
110 PRINT Y,
120 NEXT Y
130 PRINT
140 END```

### MSX Basic

Works with: Chipmunk Basic
Works with: QBasic
Works with: Quite BASIC
```10 REM Find years with Sunday Christmas
11 CLS
20 LET F = 2008
30 LET T = 2121
40 PRINT "Sunday Christmases"; F; "-"; T
50 PRINT
60 FOR Y = F TO T
70 LET E = Y * 365 + INT(Y/4) - INT(Y/100) + INT(Y/400)
80 LET X = E - 6
90 LET D = X - 7 * INT(X/7)
100 IF D <> 0 THEN 120
110 PRINT Y; " ";
120 NEXT Y
130 PRINT
140 END
```

### Palo Alto Tiny BASIC

Translation of: GW-BASIC
```10 REM DAY OF THE WEEK
20 LET M=12,D=25
30 FOR Y=2007 TO 2122
40 GOSUB 200
50 IF Z=0 PRINT Y," ",
60 NEXT Y
70 PRINT
80 STOP
170 REM CALCULATE DAY OF WEEK Z GIVEN
180 REM YEAR Y, MONTH M, AND DAY D
190 REM SUNDAY = 0, SATURDAY = 6
200 IF M<3 LET Y=Y-1,M=M+12
210 LET Z=Y+Y/4-Y/100+Y/400
220 LET Z=Z+D+(153*M+8)/5
230 LET Z=Z-(Z/7)*7
240 RETURN
```
Output:
`   2011    2016    2022    2033    2039    2044    2050    2061    2067    2072   2078    2089    2095    2101    2107    2112    2118`

### PureBasic

PureBasic's internal Date() is limited between 1970-01-01 00:00:00 and 2038-01-19 03:14:07

```For i=2008 To 2037
If DayOfWeek(Date(i,12,25,0,0,0))=0
PrintN(Str(i))
EndIf
Next```

### QBasic

Works with: QBasic version 1.1
Works with: QuickBasic version 4.5
```FOR yr = 2008 TO 2121
IF wd(12, 25, yr) = 0 THEN PRINT "Dec 25 "; yr
NEXT yr
END

FUNCTION wd (m, d, y)
IF m < 3 THEN
LET m = m + 12
LET y = y - 1
END IF
wd = ((y + INT(y / 4) - INT(y / 100) + INT(y / 400) + d + INT((153 * m + 8) / 5)) MOD 7)
END FUNCTION
```
Output:
`Same as FreeBASIC entry.`

### QL SuperBASIC

Works with: Sinclair QL
...having a structured BASIC with MOD and quite unlike the ZX81's "first-generation" BASIC that's rather like using a calculator (also without an integer type). Even so, it's worth the minor effort to optimise the code for the task at hand, as done below - which if implemented for the ZX81's routine would make it finish in a fraction of a second, even in SLOW mode, as multiplying by 13 with a division by 5 is slower than by 256 alone, as well as that two divisions by multiples of 100 are much slower than one by 16 as at the link. N.B. by relying on strings to have 4-digit years, this routine is not y10k-compliant

``` AUTO 100,10

DEF PROC Iso(S,O)
REM passing starting & ending years via integers S & O
LOCal y\$,m%,d%,i\$,n%,w%

LET m%=12 : d%=25
REM m% & d% are constants, so avoid recalculating n% (=48) each iteration
LET i\$=m%*256+ 19300 : n%=i\$(2 TO 3)+ d%
FOR count=S TO O
LET y\$=count : w%=(y\$(1 TO 2)&"32"DIV 16+ count DIV 4+ count+ n%)MOD 7
REM otherwise w%=(y\$(1 TO 2)&"16"DIV 16+ count DIV 4+ count)MOD 7
REM = further optimisation beyond skipping irrelevant years:
IF w%=0 THEN PRINT count : count = count+ 4
END FOR count
END DEF Iso

ctrl+space
```
Output:
```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118```

### Quite BASIC

The MSX Basic solution works without any changes.

### Run BASIC

```for year = 2008 to 2121
if val(date\$("12-25-";year)) mod 7 = 5 then print "For ";year;"xmas is Sunday"
next year```
```For 2011 xmas is Sunday
For 2016 xmas is Sunday
For 2022 xmas is Sunday
For 2033 xmas is Sunday
For 2039 xmas is Sunday
For 2044 xmas is Sunday
For 2050 xmas is Sunday
For 2061 xmas is Sunday
For 2067 xmas is Sunday
For 2072 xmas is Sunday
For 2078 xmas is Sunday
For 2089 xmas is Sunday
For 2095 xmas is Sunday
For 2101 xmas is Sunday
For 2107 xmas is Sunday
For 2112 xmas is Sunday
For 2118 xmas is Sunday
```

### S-BASIC

```\$constant SUNDAY = 0

rem - compute p mod q
function mod(p, q = integer) = integer
end = p - q * (p/q)

comment
return day of week (Sun = 0, Mon = 1, etc.) for a
given Gregorian calendar date using Zeller's congruence
end
function dayofweek (mo, da, yr = integer) = integer
var y, c, z = integer
if mo < 3 then
begin
mo = mo + 10
yr = yr - 1
end
else mo = mo - 2
y = mod(yr,100)
c = int(yr / 100)
z = int((26 * mo - 2) / 10)
z = z + da + y + int(y/4) + int(c/4) - 2 * c + 777
z = mod(z,7)
end = z

rem - main program
var year = integer
print "Christmas will fall on a Sunday in"
for year=2008 to 2121
if dayofweek(12,25,year) = SUNDAY then
print year
next year
end
```
Output:
```Christmas will fall on a Sunday in
2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118```

### Sinclair ZX81 BASIC

Translation of: C

Works with 1k of RAM. Follows the C code quite closely: the only factors that perhaps make it less readable are (a) the absence of a modulo operator and (b) the need for continual calls to `INT` because we don't have an integer type. The performance is pretty acceptable; seconds rather than minutes.

``` 10 LET M=12
20 LET D=25
30 FOR Y=2008 TO 2121
40 GOSUB 80
50 IF W=0 THEN PRINT Y
60 NEXT Y
70 STOP
80 LET A=INT ((14-M)/12)
90 LET MM=M+12*A-2
100 LET YY=Y-A
110 LET W=D+INT ((13*MM-1)/5)+YY+INT (YY/4)-INT (YY/100)+INT (YY/400)
120 LET W=W-7*INT (W/7)
130 RETURN```
Output:
```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118```

### TI-83 BASIC

Works with: TI-84+/SE

only

```:For(A,2008,2121
:If dayofWk(A,12,25)=1
:Disp A
:End```
Output:
```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
Done```

### Tiny BASIC

Works with: TinyBasic
```10 REM Day of the week
20 LET Y = 2007
30 LET M = 12
40 LET D = 25
50 IF Y = 2122 THEN END
60 LET Y = Y + 1
70 GOSUB 200
80 IF Z = 0 THEN PRINT Y
90 GOTO 50
170 REM Calculate day of week Z given
180 REM year Y, month M, and day D
190 REM Sunday = 0, Saturday = 6
200 IF M < 3 THEN LET Y = Y - 1
210 IF M < 3 THEN LET M = M + 12
220 LET Z = Y + Y / 4 - Y / 100 + Y / 400
230 LET Z = Z + D + (153 * M + 8) / 5
240 LET Z = Z - 7 * (Z / 7)
250 RETURN
```
Output:
```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118```

### True BASIC

```FUNCTION wd (m, d, y)
IF m < 3 THEN
LET m = m + 12
LET y = y - 1
END IF
LET wd = REMAINDER ((y + INT(y / 4) - INT(y / 100) + INT(y / 400) + d + INT((153 * m + 8) / 5)), 7)
END FUNCTION

FOR yr = 2008 TO 2121
IF wd(12, 25, yr) = 0 THEN PRINT "Dec 25 "; yr
NEXT yr
END
```
Output:
`Same as FreeBASIC entry.`

### VBA

```Option Explicit

Sub MainDayOfTheWeek()
Debug.Print "Xmas will be a Sunday in : " & XmasSunday(2008, 2121)
End Sub

Private Function XmasSunday(firstYear As Integer, lastYear As Integer) As String
Dim i As Integer, temp\$
For i = firstYear To lastYear
If Weekday(CDate("25/12/" & i)) = vbSunday Then temp = temp & ", " & i
Next
XmasSunday = Mid(temp, 2)
End Function```
Output:
`Xmas will be a Sunday in :  2011, 2016, 2022, 2033, 2039, 2044, 2050, 2061, 2067, 2072, 2078, 2089, 2095, 2101, 2107, 2112, 2118`

### VBScript

```For year = 2008 To 2121
If Weekday(DateSerial(year, 12, 25)) = 1 Then
WScript.Echo year
End If
Next```
Output:
```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
```

### XBasic

Works with: Windows XBasic
```PROGRAM	"progname"
VERSION	"0.0000"

DECLARE FUNCTION  Entry ()
DECLARE FUNCTION wd (m, d, y)

FUNCTION  Entry ()
FOR yr = 2008 TO 2121
IF wd(12, 25, yr) = 0 THEN PRINT "Dec 25 "; yr
NEXT yr

END FUNCTION

FUNCTION wd (m, d, y)
IF m < 3 THEN
m = m + 12
DEC y
END IF
RETURN ((y + INT(y / 4) - INT(y / 100) + INT(y / 400) + d + INT((153 * m + 8) / 5)) MOD 7)
END FUNCTION
END PROGRAM```
Output:
`Same as FreeBASIC entry.`

### Yabasic

Translation of: FreeBASIC
```sub wd(m, d, y)
If m < 3 Then        // If m = 1 Or m = 2 Then
m = m + 12
y = y - 1
End If
Return mod((y + int(y / 4) - int(y / 100) + int(y / 400) + d + int((153 * m + 8) / 5)), 7)
End sub

// ------=< MAIN >=------

For yr = 2008 To 2121
If wd(12, 25, yr) = 0 Then
Print "Dec 25 ", yr
EndIf
Next```

### ZX Spectrum Basic

Translation of: FreeBASIC
```10 CLS
20 FOR y=2008 TO 2121
30 LET year=y: LET m=12: LET d=25: GO SUB 1000
40 IF wd=0 THEN PRINT d;" ";m;" ";y
50 NEXT y
60 STOP
1000 REM week day
1010 IF m=1 OR m=2 THEN LET m=m+12: LET year=year-1
1020 LET wd=FN m(year+INT (year/4)-INT (year/100)+INT (year/400)+d+INT ((153*m+8)/5),7)
1030 RETURN
1100 DEF FN m(a,b)=a-INT (a/b)*b```

## Batch File

```:: Day of the Week task from Rosetta Code
:: Batch File Implementation
:: Question: In what years between 2008 and 2121 will the 25th of December be a Sunday?
:: Method: Zeller's Rule

@echo off
rem set month code for December
set mon=33
rem set day number
set day=25

for /L %%y in (2008,1,2121) do (
setlocal enabledelayedexpansion
set /a "a=%%y/100"
set /a "b=%%y-(a*100)"
set /a "weekday=(day+mon+b+(b/4)+(a/4)+(5*a))%%7"
if "!weekday!"=="1" echo(Dec 25, %%y is a Sunday.
endlocal
)
pause
exit /b 0```
Output:
```Dec 25, 2011 is a Sunday.
Dec 25, 2016 is a Sunday.
Dec 25, 2022 is a Sunday.
Dec 25, 2033 is a Sunday.
Dec 25, 2039 is a Sunday.
Dec 25, 2044 is a Sunday.
Dec 25, 2050 is a Sunday.
Dec 25, 2061 is a Sunday.
Dec 25, 2067 is a Sunday.
Dec 25, 2072 is a Sunday.
Dec 25, 2078 is a Sunday.
Dec 25, 2089 is a Sunday.
Dec 25, 2095 is a Sunday.
Dec 25, 2101 is a Sunday.
Dec 25, 2107 is a Sunday.
Dec 25, 2112 is a Sunday.
Dec 25, 2118 is a Sunday.
Press any key to continue . . .```

## bc

Because bc has no date library, this program uses Zeller's rule, also known as Zeller's congruence, to calculate day of week.

```scale = 0

/*
* Returns day of week (0 to 6) for year, month m, day d in proleptic
* Gregorian calendar. Sunday is 0. Assumes y >= 1, scale = 0.
*/
define w(y, m, d) {
auto a

/* Calculate Zeller's congruence. */
a = (14 - m) / 12
m += 12 * a
y -= a
return ((d + (13 * m + 8) / 5 +			\
y + y / 4 - y / 100 + y / 400) % 7)
}

for (y = 2008; y <= 2121; y++) {
/* If December 25 is a Sunday, print year. */
if (w(y, 12, 25) == 0) y
}
quit
```

## BCPL

```get "libhdr"

let weekday(y, m, d) =
m<3 -> wd((y-1)/100, (y-1) rem 100, m + 10, d),
wd(y/100, y rem 100, m - 2, d)
and wd(c, y, m, d) =
((26*m-2)/10 + d + y + y/4 + c/4 - 2 * c + 777) rem 7

let start() be
for year = 2008 to 2121
if weekday(year, 12, 25) = 0
do writef("%N*N", year)```
Output:
```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118```

## Befunge

Befunge doesn't have any standard date-handling functionality, so we calculate the day of the week directly using a simple variation of the Zeller rule.

```8 >:"2("*+::::4/+\"d"/-\45v
@_^#`"y": +1\$<_v#%7+1+/*:*<
>:#,_>\$:.55+,^ >0" ,52 ceD"
```
Output:
```Dec 25, 2011
Dec 25, 2016
Dec 25, 2022
Dec 25, 2033
Dec 25, 2039
Dec 25, 2044
Dec 25, 2050
Dec 25, 2061
Dec 25, 2067
Dec 25, 2072
Dec 25, 2078
Dec 25, 2089
Dec 25, 2095
Dec 25, 2101
Dec 25, 2107
Dec 25, 2112
Dec 25, 2118```

## Bracmat

Translation of: C
```{ Calculate day of week in proleptic Gregorian calendar. Sunday == 0. }
( wday
=   year month day adjustment mm yy
.   !arg:(?year,?month,?day)
&   mod
\$ (   !day
+ div\$(13*!mm+-1,5)
+ !yy
+ div\$(!yy,4)
+ -1*div\$(!yy,100)
+ div\$(!yy,400)
, 7
)
)
& 2008:?y
&   whl
' ( !y:~>2121
& (   wday\$(!y,12,25):0
& put\$(str\$(!y "-12-25\n"))
|
)
& 1+!y:?y
)
& done;```
Output:
```2011-12-25
2016-12-25
2022-12-25
2033-12-25
2039-12-25
2044-12-25
2050-12-25
2061-12-25
2067-12-25
2072-12-25
2078-12-25
2089-12-25
2095-12-25
2101-12-25
2107-12-25
2112-12-25
2118-12-25```

## C

Because of problems with various C libraries (such as time_t overflowing during 2038, or strptime() or mktime() not filling in tm_wday), this program uses Zeller's Rule to calculate day of week.

```#include <stdio.h>

/* Calculate day of week in proleptic Gregorian calendar. Sunday == 0. */
int wday(int year, int month, int day)
{

adjustment = (14 - month) / 12;
mm = month + 12 * adjustment - 2;
return (day + (13 * mm - 1) / 5 +
yy + yy / 4 - yy / 100 + yy / 400) % 7;
}

int main()
{
int y;

for (y = 2008; y <= 2121; y++) {
if (wday(y, 12, 25) == 0) printf("%04d-12-25\n", y);
}

return 0;
}
```

## C#

```using System;

class Program
{
static void Main(string[] args)
{
for (int i = 2008; i <= 2121; i++)
{
DateTime date = new DateTime(i, 12, 25);
if (date.DayOfWeek == DayOfWeek.Sunday)
{
Console.WriteLine(date.ToString("dd MMM yyyy"));
}
}
}
}
```

Using LINQ:

```using System;
using System.Linq;

class Program
{
static void Main(string[] args)
{
string[] days = Enumerable.Range(2008, 2121 - 2007)
.Select(year => new DateTime(year, 12, 25))
.Where(day => day.DayOfWeek == DayOfWeek.Sunday)
.Select(day => day.ToString("dd MMM yyyy")).ToArray();

foreach (string day in days) Console.WriteLine(day);
}
}
```

Lambda expressions FTW:

```using System;
using System.Linq;

class Program
{
static void Main(string[] args)
{
Enumerable.Range(2008, 113).ToList()
.ConvertAll(ent => new DateTime(ent, 12, 25))
.Where(ent => ent.DayOfWeek.Equals(DayOfWeek.Sunday)).ToList()
.ForEach(ent => Console.WriteLine(ent.ToString("dd MMM yyyy")));
}
}
```
Output:
```25 Dec 2011
25 Dec 2016
25 Dec 2022
25 Dec 2033
25 Dec 2039
25 Dec 2044
25 Dec 2050
25 Dec 2061
25 Dec 2067
25 Dec 2072
25 Dec 2078
25 Dec 2089
25 Dec 2095
25 Dec 2101
25 Dec 2107
25 Dec 2112
25 Dec 2118```

## C++

```#include <chrono>
#include <ranges>
#include <iostream>

int main() {
std::cout << "Yuletide holidays must be allowed in the following years:\n";
for (int year : std::views::iota(2008, 2121)
| std::views::filter([](auto year) {
if (std::chrono::weekday{
std::chrono::year{year}/std::chrono::December/25}
== std::chrono::Sunday) {
return true;
}
return false;
})) {
std::cout << year << '\n';
}
}
```
Output:
```Yuletide holidays must be allowed in the following years:
2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
```

## Clojure

Utilizing Java interop

```(import '[java.util GregorianCalendar])
(defn yuletide [start end]
(->> (range start (inc end))
(filter #(= GregorianCalendar/SUNDAY
(.get (GregorianCalendar. % GregorianCalendar/DECEMBER 25)
GregorianCalendar/DAY_OF_WEEK)))))

(println (yuletide 2008 2121))
```
Output:
`(2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2101 2107 2112 2118)`

## CLU

```weekday = proc (d: date) returns (int)
y: int := d.year
m: int := d.month
if m<3
then y, m := y-1, m+10
else m := m-2
end
c: int := y/100
y := y//100
z: int := (26*m-2)/10 + d.day + y + y/4 + c/4 - 2*c + 777
return(z//7)
end weekday

start_up = proc ()
po: stream := stream\$primary_output()
for year: int in int\$from_to(2008, 2121) do
if weekday(date\$create(25, 12, year, 0, 0, 0))=0 then
stream\$putl(po, int\$unparse(year))
end
end
end start_up```
Output:
```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118```

## COBOL

Using Date Intrinsic Functions

```       program-id. dec25.
data division.
working-storage section.
1 work-date.
2 yr pic 9(4) value 2008.
2 mo-da pic 9(4) value 1225. *> Dec 25
1 wk-date redefines work-date pic 9(8).
1 binary.
2 int-date pic 9(8).
2 dow pic 9(4).
procedure division.
perform varying yr from 2008 by 1
until yr > 2121
compute int-date = function integer-of-date (wk-date)
compute dow = function mod ((int-date - 1) 7) + 1
if dow = 7  *> Sunday = 7 per ISO 8601 and ISO 1989
display yr
end-if
end-perform
stop run
.
end program dec25.
```
Output:
```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
```

Without Date Intrinsic Functions

```       identification division.
program-id. dowtest.
data division.
working-storage section.
01  ws-inp-date   pic x(08).
01  filler redefines ws-inp-date.
03  ws-inp-year  pic 9(04).
01  ws-dow        pic 9(05).
procedure division.
move '00001225' to ws-inp-date
perform test before
varying ws-inp-year from 2008 by +1
until ws-inp-year > 2121
call "todow" using
by reference ws-inp-date
by reference ws-dow
if ws-dow = 1 then
display 'year=' ws-inp-year
end-if
end-perform
stop run.

end program dowtest.

identification division.
program-id.  todow.
environment division.
input-output section.
file-control.
data division.
file section.
working-storage section.
01 tally pic 9(05).
01  wms-work-area.
03  wms-year       pic 9(04).
03  wms-month      pic 9(02).
03  wms-csys       pic 9(01) value 1.
03  wms-sum        pic 9(05).
01  lkip-date.
03  lkip-date-year     pic 9(04).
03  lkip-date-month    pic 9(02).
03  lkip-date-day      pic 9(02).
01  lkop-dow             pic 9(05).
88  lkop-sunday                   value 1.
procedure division using
by reference lkip-date
by reference lkop-dow
.

if lkip-date-month < 3
compute wms-month = lkip-date-month + 12
compute wms-year  = lkip-date-year - 1
else
compute wms-month = lkip-date-month
compute wms-year  = lkip-date-year
end-if

compute wms-sum    =
( lkip-date-day + 2 * wms-month + wms-year
+ function integer (6 * (wms-month + 1) / 10)
+ function integer ( wms-year / 4   )
- function integer ( wms-year / 100 )
+ function integer ( wms-year / 400 )
+ wms-csys )
compute lkop-dow = function mod (wms-sum, 7) + 1
.
end program todow.
```
Output:
```year=2011
year=2016
year=2022
year=2033
year=2039
year=2044
year=2050
year=2061
year=2067
year=2072
year=2078
year=2089
year=2095
year=2101
year=2107
year=2112
year=2118
```

## CoffeeScript

```december = 11 # gotta love Date APIs :)
sunday = 0
for year in [2008..2121]
xmas = new Date year, december, 25
console.log year if xmas.getDay() is sunday
```

one-liner:

```console.log year for year in [2008...2121] when new Date(year, 11, 25).getDay() is 0
```
Output:
```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
```

## ColdFusion

```<cfloop from = "2008" to = "2121" index = "i">
<cfset myDate = createDate(i, 12, 25) />
<cfif dayOfWeek(myDate) eq 1>
December 25th falls on a Sunday in <cfoutput>#i#</cfoutput><br />
</cfif>
</cfloop>```

## Common Lisp

```(loop for year from 2008 upto 2121
when (= 6 (multiple-value-bind
(second minute hour date month year day-of-week dst-p tz)
(decode-universal-time (encode-universal-time 0 0 0 25 12 year))
(declare (ignore second minute hour date month year dst-p tz))
day-of-week))
collect year)
```
```(loop for year from 2008 upto 2121
for xmas = (encode-universal-time 0 0 0 25 12 year)
for day  = (nth-value 6 (decode-universal-time xmas))
when (= day 6) collect year)
```

## Component Pascal

```MODULE DayOfWeek;
IMPORT DevCommanders, TextMappers, Dates, StdLog;

PROCEDURE XmastOnSun(s,e: INTEGER);
VAR
i: INTEGER;
d: Dates.Date;
BEGIN
i := s;d.day := 25;d.month := 12;
WHILE i < e DO
d.year := i;
IF Dates.DayOfWeek(d) = Dates.sunday THEN
StdLog.Int(i);StdLog.Ln
END;
INC(i)
END
END XmastOnSun;

PROCEDURE Do*;
VAR
s: TextMappers.Scanner;
r: ARRAY 2 OF INTEGER;
i: INTEGER;
BEGIN
s.ConnectTo(DevCommanders.par.text);
s.SetPos(DevCommanders.par.beg);
s.Scan;i := 0;
WHILE ~s.rider.eot DO
IF s.type = TextMappers.int THEN
r[i] := s.int; INC(i)
END;
s.Scan
END;
XmastOnSun(r[0],r[1]);
END Do;

END DayOfWeek.```

Execute: ^Q DayOfWeek.Do 2008 2121~

Output:
``` 2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
```

## Cowgol

```include "cowgol.coh";

sub weekday(year: uint16, month: uint8, day: uint8): (wd: uint8) is
if month < 3 then
month := month + 10;
year := year - 1;
else
month := month - 2;
end if;
var c := year / 100;
var y := year % 100;
var z := (26 * month as uint16 - 2) / 10;
z := z + day as uint16 + y + (y / 4) + (c / 4) - 2 * c + 777;
wd := (z % 7) as uint8;
end sub;

var year: uint16 := 2008;
while year <= 2121 loop
if weekday(year, 12, 25) == 0 then
print_i16(year);
print_nl();
end if;
year := year + 1;
end loop;```
Output:
```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118```

## D

```void main() {
import std.stdio, std.range, std.algorithm, std.datetime;

writeln("Christmas comes on a Sunday in the years:\n",
iota(2008, 2122)
.filter!(y => Date(y, 12, 25).dayOfWeek == DayOfWeek.sun));
}
```
Output:
```Christmas comes on a Sunday in the years:
[2011, 2016, 2022, 2033, 2039, 2044, 2050, 2061, 2067, 2072, 2078, 2089, 2095, 2101, 2107, 2112, 2118]```

## Delphi

Library: sysutils

always in uses clause in Delphi

```procedure IsXmasSunday(fromyear, toyear: integer);
var
i: integer;
TestDate: TDateTime;
outputyears: string;
begin
outputyears := '';
for i:= fromyear to toyear do
begin
TestDate := EncodeDate(i,12,25);
if dayofweek(TestDate) = 1 then
begin
outputyears := outputyears + inttostr(i) + ' ';
end;
end;
//CONSOLE
//writeln(outputyears);
//GUI
form1.label1.caption := outputyears;
end;
```

Procedure called with year range to test and outputs a space-delimited array of years to a label. There is no error check that fromyear < toyear, but this is easily added.

Output:
```2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2101 2107 2112 2118
```

## Draco

```proc nonrec weekday(word y, m, d) byte:
word c;
if m<3 then
m := m+10;
y := y+1
else
m := m-2
fi;
c := y/100;
y := y%100;
((26 * m - 2)/10 + d + y + y/4 + c/4 - 2*c + 777) % 7
corp

proc nonrec main() void:
word year;
for year from 2008 upto 2121 do
if weekday(year, 12, 25)=0 then
writeln(year)
fi
od
corp```
Output:
```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118```

## EasyLang

```func dayOfTheWeek year month day .
# Based on Conway's doomsday algorithm
# 1. Calculate the doomsday for the century
century = floor (year / 100)
if century mod 4 = 0
centuryDoomsday = 2
elif century mod 4 = 1
centuryDoomsday = 0
elif century mod 4 = 2
centuryDoomsday = 5
elif century mod 4 = 3
centuryDoomsday = 3
.
# 2. Find the doomsday of the year
mainYear = year mod 100
yearDoomsday = (floor (mainYear / 12) + mainYear mod 12 + floor (mainYear mod 12 / 4) + centuryDoomsday) mod 7
# 3. Check if the year is leap
if mainYear = 0
if century mod 4 = 0
leap = 1
else
leap = 0
.
else
if mainYear mod 4 = 0
leap = 1
else
leap = 0
.
.
# 4. Calculate the DOTW of January 1
if leap = 1
januaryOne = (yearDoomsday + 4) mod 7
else
januaryOne = (yearDoomsday + 5) mod 7
.
# 5. Determine the nth day of the year
if month = 1
NthDay = 0
elif month = 2
NthDay = 31
elif month = 3
NthDay = 59 + leap
elif month = 4
NthDay = 90 + leap
elif month = 5
NthDay = 120 + leap
elif month = 6
NthDay = 151 + leap
elif month = 7
NthDay = 181 + leap
elif month = 8
NthDay = 212 + leap
elif month = 9
NthDay = 243 + leap
elif month = 10
NthDay = 273 + leap
elif month = 11
NthDay = 304 + leap
elif month = 12
NthDay = 334 + leap
.
NthDay += day
# 6. Finally, calculate the day of the week
return (januaryOne + NthDay - 1) mod 7
.
for i = 2008 to 2121
if dayOfTheWeek i 12 25 = 0
print "Christmas in " & i & " is on Sunday"
.
.```
Output:
```Christmas in 2011 is on Sunday
Christmas in 2016 is on Sunday
Christmas in 2022 is on Sunday
Christmas in 2033 is on Sunday
Christmas in 2039 is on Sunday
Christmas in 2044 is on Sunday
Christmas in 2050 is on Sunday
Christmas in 2061 is on Sunday
Christmas in 2067 is on Sunday
Christmas in 2072 is on Sunday
Christmas in 2078 is on Sunday
Christmas in 2089 is on Sunday
Christmas in 2095 is on Sunday
Christmas in 2101 is on Sunday
Christmas in 2107 is on Sunday
Christmas in 2112 is on Sunday
Christmas in 2118 is on Sunday
```

## ECL

```//In what years between 2008 and 2121 will the 25th of December be a Sunday?

IMPORT STD;

BaseYear := 2008;
EndYear  := 2121;

ChristmasDay := RECORD
UNSIGNED1 DayofWeek;
UNSIGNED2 Year;
END;

ChristmasDay FindDate(INTEGER Ctr) := TRANSFORM
SELF.DayofWeek := (STD.Date.FromGregorianYMD((BaseYear-1) + Ctr,12,25)) % 7; //0=Sunday
SELF.Year := (BaseYear-1) + Ctr;
END;

YearDS := DATASET(EndYear-BaseYear,FindDate(COUNTER));
OUTPUT(YearDS(DayofWeek=0),{Year});

/* Outputs:
2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
*/
```

This code solves a specific task, but can easily be modified as a generic function to return the DayOfWeek for any day after 1 AD.

## EDSAC order code

Uses a version of Zeller's congruence that finds the day of the week for any Gregorian date up to 28 Feb 43699.

```[Day of week for Rosetta Code.]
[EDSAC program, Initial Orders 2.]

[Library subroutine M3 - prints header and is then overwritten.]
[Here, the last character sets the teleprinter to figures.]
PF GK IF AF RD LF UF OF E@ A6F G@ E8F EZ PF
*CHRISTMAS!DAY!ON!SUNDAY@&#
..PZ          [blank tape, then resync]

[Subroutine to find day of week in Gregorian calendar, by Zeller's method.]
[This EDSAC implementation is valid up to and including 28 Feb 43699.]
[Input:  4F = year, 5F = month, 6F = day of month (all preserved).]
[Output: 7F = day of week: 0 = Saturday, 1 = Sunday, ..., 6 = Friday.]
[Workspace: 0F]
T128K GK
A3F T41@      [plant return link as usual]
[January and February are taken as months 13 and 14 of the previous year]
S43@          [subtract 3 to test for Jan or Feb]
E9@           [jump if not Jan or Feb]
A45@          [add 16 to make month + 1]
T7F           [to 7F]
S42@          [acc := -1]
G11@          [join common code]
[9]   A44@          [not Jan, Feb; make month + 1]
T7F           [to 7F; acc := 0]
[11]   A4F           [here with acc = 0 or -1; add year]
H46@          [mult reg := 13/20 (near enough)]
V7F           [times (month + 1)]
L1F           [shift 2 left]
T7F           [7F := 13*(month + 1) div 5]
AF            [year]
R1F           [shift 2 right]
AF            [year + (year div 4)]
T7F
H47@          [mult reg := 64/100 (approx, OK for dates as above)]
VF            [times year]
R16F          [shift 6 right]
UF            [0F := year div 100]
R1F           [shift 2 more right]
SF            [(year div 400) - (year div 100)]
T7F
[Finally take 7F modulo 7. Suppose 7F = 7*q + r (0 <= r < 7)]
H48@          [mult reg := 4/7 (near enough)]
V7F           [acc := 4*q + (4/7)*r]
R1F           [shift 2 right: acc := q + r/7]
TF            [0F := acc high word = q]
H49@          [mult reg := 7/8 (exact)]
A7F           [acc := 7*q + r]
R2F           [shift 3 right, acc := (7*q + r)/8]
NF            [subtract (7/8)*q, acc := r/8]
L2F           [shift 3 left, acc := r as required]
T7F           [return result r in 7F]
[41]   ZF            [(planted) jump back to caller]
[Constants]
[42]   PD            [1]
[43]   P1D           [3]
[44]   P2F           [4]
[45]   P8F           [16]
[46]   J819D         [0.A667 hex, approx 13/20]
[47]   J492F         [0.A3D8 hex, approx 64/100]
[48]   O293F         [0.924A hex, approx 4/7]
[49]   KF            [0.1110 hex = 7/8]

[Subroutine to print non-negative 17-bit integer.]
[Parameters: 0F = integer to be printed (not preserved)
1F = character for leading zero (preserved)]
[Workspace: 4F..7F, 38 locations]
T64K
GK A3F T34@ A1F T7F S35@ T6F T4#F AF T4F H36@ V4F RD A4#F R1024F H37@ E23@ O7F A2F
T6F T5F V4#F YF L8F T4#F A5F L1024F UF A6F G16@ OF TF T7F A6F G17@ ZF P4F Z219D TF

[Main routine]
T400K GK
[Constants]
[0]   P1004F        [2008]
[1]   P1060D        [2121]
[2]   P6F           [12 (December)]
[3]   P12D          [25]
[4]   PD            [1]
[5]   @F            [carriage return]
[6]   &F            [line feed]
[7]   K4096F        [null char]
[Variable]
[8]   PF            [year]
[Enter with acc = 0]
[9]   A7@ T1F       [1F := null for print subroutine]
[12]   U8@ T4F       [save year, and pass to Zeller subroutine]
A2@ T5F       [pass month 12 to Zeller subroutine]
A3@ T6F       [pass day 25 to Zeller subroutine]
A18@ G128F    [call Zeller subroutine]
A7F S4@       [load day of week, subtract 1]
G32@          [jump if day = 0]
S4@ E32@      [subtract 1, jump if day >= 2]
TF            [here if day = 1 (Sunday); clear acc]
A4F TF        [pass year to print subroutine]
A28@ G64F     [call print subroutine (overwrites 4F)]
O5@ O6@       [print CR, LF]
[32]   TF            [common code; clear acc]
A8@ S1@       [test for end]
A1@           [restore acc after test]
A4@ E12@      [inc year and loop back]
[39]   O7@           [done; print null]
ZF            [halt the machine]

E9Z           [define entry point]
PF            [acc = 0 on entry]
[end]```
Output:
```CHRISTMAS DAY ON SUNDAY
2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
```

## Elixir

Works with: Elixir version 1.4
```Enum.each(2008..2121, fn year ->
wday = Date.from_erl!({year, 12, 25}) |> Date.day_of_week
if wday==7, do: IO.puts "25 December #{year} is sunday"
end)
```
Output:
```25 December 2011 is sunday
25 December 2016 is sunday
25 December 2022 is sunday
25 December 2033 is sunday
25 December 2039 is sunday
25 December 2044 is sunday
25 December 2050 is sunday
25 December 2061 is sunday
25 December 2067 is sunday
25 December 2072 is sunday
25 December 2078 is sunday
25 December 2089 is sunday
25 December 2095 is sunday
25 December 2101 is sunday
25 December 2107 is sunday
25 December 2112 is sunday
25 December 2118 is sunday
```

## Emacs Lisp

```(require 'calendar)

(defun sunday-p (y)
"Is Dec 25th a Sunday in this year?"
(= (calendar-day-of-week (list 12 25 y)) 0))

(defun xmas-sunday (a b)
"In which years in the range a, b is Dec 25th a Sunday?"
(seq-filter #'sunday-p (number-sequence a b)))

(print (xmas-sunday 2008 2121))
```
Output:
`(2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2101 2107 2112 2118)`

## Erlang

```% Implemented by bengt kleberg
-module(yuletide).
-export([main/0, sunday_years/2]).

main() ->
[io:fwrite("25 December ~p is Sunday~n", [X]) || X <- sunday_years(2008, 2121)].

sunday_years( Start, Stop ) ->
[X || X <- lists:seq(Start, Stop), is_sunday(calendar:day_of_the_week({X, 12, 25}))].

is_sunday( 7 ) -> true;
is_sunday( _ ) -> false.
```
Output:
```25 December 2011 is Sunday
25 December 2016 is Sunday
25 December 2022 is Sunday
25 December 2033 is Sunday
25 December 2039 is Sunday
25 December 2044 is Sunday
25 December 2050 is Sunday
25 December 2061 is Sunday
25 December 2067 is Sunday
25 December 2072 is Sunday
25 December 2078 is Sunday
25 December 2089 is Sunday
25 December 2095 is Sunday
25 December 2101 is Sunday
25 December 2107 is Sunday
25 December 2112 is Sunday
25 December 2118 is Sunday
```

## ERRE

```PROGRAM DAY_OF_THE_WEEK

PROCEDURE MODULO(X,Y->RES)
IF Y=0 THEN
RES=X
ELSE
RES=X-Y*INT(X/Y)
END IF
END PROCEDURE

PROCEDURE WD(M,D,Y->RES%)
IF M=1 OR M=2 THEN
M+=12
Y-=1
END IF
MODULO(365*Y+INT(Y/4)-INT(Y/100)+INT(Y/400)+D+INT((153*M+8)/5),7->RES)
RES%=RES+1.0
END PROCEDURE

BEGIN
PRINT(CHR\$(12);) ! CLS
FOR YR=2008 TO 2121 DO
WD(12,25,YR->RES%)
IF RES%=1 THEN  ! day 1 is Sunday......
PRINT("Dec";25;",";YR)
END IF
END FOR
GET(K\$)
END PROGRAM```
Output:
```Dec 25, 2011
Dec 25, 2016
Dec 25, 2022
Dec 25, 2033
Dec 25, 2039
Dec 25, 2044
Dec 25, 2050
Dec 25, 2061
Dec 25, 2067
Dec 25, 2072
Dec 25, 2078
Dec 25, 2089
Dec 25, 2095
Dec 25, 2101
Dec 25, 2107
Dec 25, 2112
Dec 25, 2118
```

## Euphoria

```--Day of the week task from Rosetta Code wiki
--User:Lnettnay

--In what years between 2008 and 2121 will the 25th of December be a Sunday

include std/datetime.e

datetime dt

for year = 2008 to 2121 do
dt = new(year, 12, 25)
if weeks_day(dt) = 1 then -- Sunday = 1
? year
end if
end for```
Output:
```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
```

## F#

```open System

[ 2008 .. 2121 ]
|> List.choose (fun y -> if DateTime(y,12,25).DayOfWeek = DayOfWeek.Sunday then Some(y) else None)
|> printfn "%A"
```
Output:
```[2011; 2016; 2022; 2033; 2039; 2044; 2050; 2061; 2067; 2072; 2078; 2089; 2095;
2101; 2107; 2112; 2118]```

## Factor

```USING: calendar math.ranges prettyprint sequences ;
2008 2121 [a,b] [ 12 25 <date> sunday? ] filter .
```

## Forth

Forth has only TIME&DATE, which does not give day of week. Many public Forth Julian date calculators had year-2100 problems, but this algorithm works well.

```\ Zeller's Congruence
: weekday ( d m y -- wd) \ 1 mon..7 sun
over 3 < if 1- swap 12 + swap then
100 /mod
dup 4 / swap 2* -
swap dup 4 / + +
swap 1+ 13 5 */ + +
( in zeller 0=sat, so -2 to 0= mon, then mod, then 1+ for 1=mon)
2- 7 mod 1+ ;

: yuletide
." December 25 is Sunday in "
2122 2008 do
25 12 i weekday
7 = if i . then
loop cr ;
```
```cr yuletide
December 25 is Sunday in 2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2101 2107 2112 2118
ok
```

To show year-2100 problems with SwiftForth's provided Modified Julian Day support:

```: yuletide
." December 25 is Sunday in "
2122 2008 do
25 12 i d/m/y
7 mod 0= if i . then
loop cr ;

cr yuletide
December 25 is Sunday in 2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2100 2106 2117
```

In 4tH a library is available which provides the right answer:

```include lib/time.4th

: yuletide
." December 25 is Sunday in "
2122 2008 do
25 12 i weekday
6 = if i . then
loop cr ;

cr yuletide
```

The code is derived from "Collected Algorithms from ACM", Volume 1 Algorithms 1-220.

## Fortran

Works with: Fortran version 90 and later

Based on Forth example

```PROGRAM YULETIDE

IMPLICIT NONE

INTEGER :: day, year

WRITE(*, "(A)", ADVANCE="NO") "25th of December is a Sunday in"
DO year = 2008, 2121
day = Day_of_week(25, 12, year)
IF (day == 1) WRITE(*, "(I5)", ADVANCE="NO") year
END DO

CONTAINS

FUNCTION Day_of_week(d, m, y)
INTEGER :: Day_of_week, j, k, mm, yy
INTEGER, INTENT(IN) :: d, m, y

mm=m
yy=y
IF(mm.le.2) THEN
mm=mm+12
yy=yy-1
END IF
j = yy / 100
k = MOD(yy, 100)
Day_of_week = MOD(d + ((mm+1)*26)/10 + k + k/4 + j/4 + 5*j, 7)
END FUNCTION Day_of_week

END PROGRAM YULETIDE
```
Output:
``` 25th of December is a Sunday in 2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2101 2107 2112 2118
```

## Fōrmulæ

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

Programs in Fōrmulæ are created/edited online in its website.

In this page you can see and run the program(s) related to this task and their results. You can also change either the programs or the parameters they are called with, for experimentation, but remember that these programs were created with the main purpose of showing a clear solution of the task, and they generally lack any kind of validation.

Solution

## Frink

```for y = 2008 to 2121
if (parseDate["\$y-12-25"] -> ### u ###) == "7"
println[y]```
Output:
```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
```

## GAP

```Filtered([2008 .. 2121], y -> WeekDay([25, 12, y]) = "Sun");
# [ 2011, 2016, 2022, 2033, 2039, 2044, 2050, 2061, 2067, 2072, 2078, 2089, 2095, 2101, 2107, 2112, 2118 ]

# A possible implementation of WeekDayAlt

days := ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"];;

WeekDayAlt := function(args)
local d, m, y, k;
d := args[1];
m := args[2];
y := args[3];
if m < 3 then
m := m + 12;
y := y - 1;
fi;
k := 1 + RemInt(d + QuoInt((m + 1)*26, 10) + y + QuoInt(y, 4)
+ 6*QuoInt(y, 100) + QuoInt(y, 400) + 5, 7);
return days[k];
end;

Filtered([2008 .. 2121], y -> WeekDayAlt([25, 12, y]) = "Sun");
# [ 2011, 2016, 2022, 2033, 2039, 2044, 2050, 2061, 2067, 2072, 2078, 2089, 2095, 2101, 2107, 2112, 2118 ]
```

## Go

```package main

import "fmt"
import "time"

func main() {
for year := 2008; year <= 2121; year++ {
if time.Date(year, 12, 25, 0, 0, 0, 0, time.UTC).Weekday() ==
time.Sunday {
fmt.Printf("25 December %d is Sunday\n", year)
}
}
}
```
Output:
```25 December 2011 is Sunday
25 December 2016 is Sunday
25 December 2022 is Sunday
25 December 2033 is Sunday
25 December 2039 is Sunday
25 December 2044 is Sunday
25 December 2050 is Sunday
25 December 2061 is Sunday
25 December 2067 is Sunday
25 December 2072 is Sunday
25 December 2078 is Sunday
25 December 2089 is Sunday
25 December 2095 is Sunday
25 December 2101 is Sunday
25 December 2107 is Sunday
25 December 2112 is Sunday
25 December 2118 is Sunday
```

## Groovy

Solution:

```def yuletide = { start, stop -> (start..stop).findAll { Date.parse("yyyy-MM-dd", "\${it}-12-25").format("EEE") == "Sun" } }
```

Test program:

```println yuletide(2008, 2121)
```
Output:
`[2011, 2016, 2022, 2033, 2039, 2044, 2050, 2061, 2067, 2072, 2078, 2089, 2095, 2101, 2107, 2112, 2118]`

Using the time library:

```import Data.Time (fromGregorian)
import Data.Time.Calendar.WeekDate (toWeekDate)

--------------------- DAY OF THE WEEK --------------------

isXmasSunday :: Integer -> Bool
isXmasSunday year = 7 == weekDay
where
(_, _, weekDay) = toWeekDate \$ fromGregorian year 12 25

--------------------------- TEST -------------------------
main :: IO ()
main =
mapM_
putStrLn
[ "Sunday 25 December " <> show year
| year <- [2008 .. 2121],
isXmasSunday year
]
```
Output:
```Sunday 25 December 2011
Sunday 25 December 2016
Sunday 25 December 2022
Sunday 25 December 2033
Sunday 25 December 2039
Sunday 25 December 2044
Sunday 25 December 2050
Sunday 25 December 2061
Sunday 25 December 2067
Sunday 25 December 2072
Sunday 25 December 2078
Sunday 25 December 2089
Sunday 25 December 2095
Sunday 25 December 2101
Sunday 25 December 2107
Sunday 25 December 2112
Sunday 25 December 2118```

The built-in System.Time module can overflow at the Unix epoch in 2038:

```import System.Time

isXmasSunday :: Int -> Bool
isXmasSunday year = ctWDay cal == Sunday
where
cal = toUTCTime \$ toClockTime cal'
cal' =
CalendarTime
{ ctYear = year
, ctMonth = December
, ctDay = 25
, ctHour = 0
, ctMin = 0
, ctSec = 0
, ctPicosec = 0
, ctWDay = Friday
, ctYDay = 0
, ctTZName = ""
, ctTZ = 0
, ctIsDST = False
}

main :: IO ()
main =
mapM_
putStrLn
[ "25 December " ++ show year ++ " is Sunday"
| year <- [2008 .. 2121]
, isXmasSunday year ]
```
Output:

on 32-bit machine

```25 December 2011 is Sunday
25 December 2016 is Sunday
25 December 2022 is Sunday
25 December 2033 is Sunday
*** Exception: user error (Time.toClockTime: invalid input)
```

but with 64 bit systems, running current versions of GHC:

```25 December 2011 is Sunday
25 December 2016 is Sunday
25 December 2022 is Sunday
25 December 2033 is Sunday
25 December 2039 is Sunday
25 December 2044 is Sunday
25 December 2050 is Sunday
25 December 2061 is Sunday
25 December 2067 is Sunday
25 December 2072 is Sunday
25 December 2078 is Sunday
25 December 2089 is Sunday
25 December 2095 is Sunday
25 December 2101 is Sunday
25 December 2107 is Sunday
25 December 2112 is Sunday
25 December 2118 is Sunday```

## HicEst

```DO year = 1, 1000000
TIME(Year=year, MOnth=12, Day=25, TO, WeekDay=weekday)
IF( weekday == 7) WRITE(StatusBar) year
ENDDO

END```
```No anomalies detected for the first million years :-)
Dec 25 = Sunday in
5 ... 2011 2016 2022 2033 2039 2044 2050 2061 2067
2072 2078 2089 2095 2101 2107 2112 2118 ... 999994
```

## Icon and Unicon

```link datetime

procedure main()
writes("December 25th is a Sunday in: ")
every writes((dayoweek(25,12,y := 2008 to 2122)=="Sunday",y)," ")
end
```

```procedure dayoweek(day, month, year)	#: day of the week
static d_code, c_code, m_code, ml_code, y, C, M, Y

initial {
d_code := ["Saturday", "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday"]

c_code := table()
c_code[16] := c_code[20] := 0
c_code[17] := c_code[21] := 6
c_code[18] := c_code[22] := 4
c_code[19] := c_code[23] := 2

m_code := table()
m_code[1] := m_code["January"] := 1
m_code[2] := m_code["February"] := 4
m_code[3] := m_code["March"] := 4
m_code[4] := m_code["April"] := 0
m_code[5] := m_code["May"] := 2
m_code[6] := m_code["June"] := 5
m_code[7] := m_code["July"] := 0
m_code[8] := m_code["August"] := 3
m_code[9] := m_code["September"] := 6
m_code[10] := m_code["October"] := 1
m_code[11] := m_code["November"] := 4
m_code[12] := m_code["December"] := 6

ml_code := copy(m_code)
ml_code[1] := ml_code["January"] := 0
ml_code[2] := ml_code["February"] := 3
}

if year < 1600 then stop("*** can't compute day of week that far back")
if year > 2299 then stop("*** can't compute day of week that far ahead")

C := c_code[(year / 100) + 1]
y := year % 100
Y := (y / 12) + (y % 12) + ((y % 12) / 4)
month := integer(month)
M := if (year % 4) = 0 then ml_code[month] else m_code[month]

return d_code[(C + Y + M + day) % 7 + 1]

end
```
Output:
`December 25th is a Sunday in: 2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2101 2107 2112 2118`

## J

```   load 'dates'                                    NB. provides verb 'weekday'
xmasSunday=: #~ 0 = [: weekday 12 25 ,~"1 0 ]   NB. returns years where 25 Dec is a Sunday
xmasSunday 2008 + i.114                         NB. check years from 2008 to 2121
2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2101 2107 2112 2118
```

## Java

```import static java.util.Calendar.*;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;

public class Yuletide{
public static void main(String[] args) {
Calendar calendar;
int count = 1;
for (int year = 2008; year <= 2121; year++) {
calendar = new GregorianCalendar(year, DECEMBER, 25);
if (calendar.get(DAY_OF_WEEK) == SUNDAY) {
if (count != 1)
System.out.print(", ");
System.out.printf("%d", calendar.get(YEAR));
count++;
}
}
}
}
```
Output:
```2011, 2016, 2022, 2033, 2039, 2044, 2050, 2061, 2067, 2072, 2078, 2089, 2095, 2101, 2107, 2112, 2118
```

## JavaScript

### ES5

#### Iteration

```for (var year = 2008; year <= 2121; year++){
var xmas = new Date(year, 11, 25)
if ( xmas.getDay() === 0 )
console.log(year)
}
```
Output:
```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118```

#### Functional composition

```(function () {
'use strict';

// isXmasSunday :: Integer -> Bool
function isXmasSunday(year) {
return (new Date(year, 11, 25))
.getDay() === 0;
}

// range :: Int -> Int -> [Int]
function range(m, n) {
return Array.apply(null, Array(n - m + 1))
.map(function (_, i) {
return m + i;
});
}

return range(2008, 2121)
.filter(isXmasSunday);

})();
```
Output:
```[2011, 2016, 2022, 2033, 2039, 2044, 2050, 2061, 2067,
2072, 2078, 2089, 2095, 2101, 2107, 2112, 2118]```

### ES6

```(() => {
"use strict";

// main :: IO ()
const main = () => {
const
xs = enumFromTo(2008)(2121)
.filter(xmasIsSunday);

return (
console.log(xs),
xs
);
};

// xmasIsSunday :: Int -> Bool
const xmasIsSunday = year =>
(new Date(year, 11, 25))
.getDay() === 0;

// enumFromTo :: Int -> Int -> [Int]
const enumFromTo = m =>
n => Array.from({
length: 1 + n - m
}, (_, i) => m + i);

// MAIN ---
return main();
})();
```
Output:
```[2011, 2016, 2022, 2033, 2039, 2044, 2050, 2061, 2067, 2072, 2078, 2089, 2095, 2101, 2107, 2112, 2118]
```

## jq

```# Use Zeller's Congruence to determine the day of the week, given
# year, month and day as integers in the conventional way.
# If iso == "iso" or "ISO", then emit an integer in 1 -- 7 where
# 1 represents Monday, 2 Tuesday, etc;
# otherwise emit 0 for Saturday, 1 for Sunday, etc.
#
def day_of_week(year; month; day; iso):
if month == 1 or month == 2 then
[month + 12, year - 1]
else
[month, year]
end
| day + (13*(.[0] + 1)/5|floor)
+  (.[1]%100)       + ((.[1]%100)/4|floor)
+  (.[1]/400|floor) - 2*(.[1]/100|floor)
| if iso == "iso" or iso == "ISO" then 1 + ((. + 5) % 7)
else . % 7
end;```

```# Give the results as an array so they can
# readily be presented on a single line:
[range(2008; 2122) | select( day_of_week(.;12;25;0) == 1 )]```
Output:
```\$ jq -n -c -f zeller.jq
[2011,2016,2022,2033,2039,2044,2050,2061,2067,2072,2078,2089,2095,2101,2107,2112,2118]
```

## Jsish

Jsi does not yet implement the Javascript Date object. strftime' and strptime functions are used here instead.

```/* Day of the week, December 25th on a Sunday */
for (var year = 2008; year <= 2121; year++) {
var xmas = strptime(year + '/12/25', '%Y/%m/%d');
var weekDay = strftime(xmas, '%w');
if (weekDay == 0) puts(year);
}

/*
=!EXPECTSTART!=
2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
=!EXPECTEND!=
*/
```
Output:
```prompt\$ jsish -u dayOfTheWeek.jsi
[PASS] dayOfTheWeek.jsi```

## Julia

```using Dates

lo, hi = 2008, 2121
xmas = collect(Date(lo, 12, 25):Year(1):Date(hi, 12, 25))
filter!(xmas) do dt
dayofweek(dt) == Dates.Sunday
end

println("Years from \$lo to \$hi having Christmas on Sunday: ")
foreach(println, year.(xmas))
```
Output:
```Years from 2008 to 2121 having Christmas on Sunday:
2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118```

## K

```    wd:{(__jd x)!7}  / Julian day count, Sun=6
y@&6={wd 1225+x*10000}'y:2008+!114
2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2101 2107 2112 2118
```

## Koka

```import std/time/date
import std/time/calendar
import std/time/instant
import std/time/utc

fun main()
for(2008, 2121) fn(year)
val i = instant(year, 12, 25, cal=cal-gregorian)
val dow  = (i.days+6)%7  // plus 6 since 2000-01-01 epoch was a Saturday
match dow.weekday
Sun -> println(year.show)
_      -> ()
```
Output:
```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
```

## Kotlin

```// version 1.0.6

import java.util.*

fun main(args: Array<String>) {
println("Christmas day in the following years falls on a Sunday:\n")
val calendar = GregorianCalendar(2008, Calendar.DECEMBER, 25)
for (year in 2008..2121) {
if (Calendar.SUNDAY == calendar[Calendar.DAY_OF_WEEK]) println(year)
}
}
```
Output:
```Christmas day in the following years falls on a Sunday:

2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
```

## Lambdatalk

Translation of: Javascript
```{xmasOnSunday 2008 2121}
->
2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118

{script
LAMBDATALK.DICT["xmasOnSunday"] = function() {
var args = arguments[0].trim().split(" "),
days = [];

for (var year = args[0]; year <= args[1]; year++) {
var xmas = new Date(year, 11, 25)
if ( xmas.getDay() === 0 )
days.push(year)
}

return days.join("\n")
};
}
```

## Lasso

```loop(-From=2008, -to=2121) => {^
local(tDate = date('12/25/' + loop_count))
#tDate->dayOfWeek == 1 ? '\r' + #tDate->format('%D') + ' is a Sunday'
^}
```
Output:
```12/25/2011 is a Sunday
12/25/2016 is a Sunday
12/25/2022 is a Sunday
12/25/2033 is a Sunday
12/25/2039 is a Sunday
12/25/2044 is a Sunday
12/25/2050 is a Sunday
12/25/2061 is a Sunday
12/25/2067 is a Sunday
12/25/2072 is a Sunday
12/25/2078 is a Sunday
12/25/2089 is a Sunday
12/25/2095 is a Sunday
12/25/2101 is a Sunday
12/25/2107 is a Sunday
12/25/2112 is a Sunday
12/25/2118 is a Sunday```

## Lingo

```put "December 25 is a Sunday in:"
refDateObj = date(1905,1,2)
repeat with year = 2008 to 2121
dateObj = date(year, 12, 25)
dayOfWeek = ((dateObj - refDateObj) mod 7)+1 -- 1=Monday..7=Sunday
if dayOfWeek=7 then put year
end repeat```
Output:
```-- "December 25 is a Sunday in:"
-- 2011
-- 2016
-- 2022
-- 2033
-- 2039
-- 2044
-- 2050
-- 2061
-- 2067
-- 2072
-- 2078
-- 2089
-- 2095
-- 2101
-- 2107
-- 2112
-- 2118
```

## LiveCode

```function xmasSunday startDate endDate
convert the long date to dateitems
put it into xmasDay
put 12 into item 2 of xmasDay
put 25 into item 3 of xmasDay
repeat with i = startDate to endDate
put i into item 1 of xmasDay
convert xmasDay to dateItems
if item 7 of xmasDay is 1 then put i & comma after xmasYear
end repeat
if the last char of xmasYear is comma then delete the last char of xmasYear
return xmasYear
end xmasSunday```

Example

`put xmasSunday(2008,2121)`

Output

`2011,2016,2022,2033,2039,2044,2050,2061,2067,2072,2078,2089,2095,2101,2107,2112,2118`

## Logo

```; Determine if a Gregorian calendar year is leap
to leap? :year
output (and
equal? 0 modulo :year 4
not member? modulo :year 400 [100 200 300]
)
end

; Convert Gregorian calendar date to a simple day count from
; day 1 = January 1, 1 CE
to day_number :year :month :day
local "elapsed make "elapsed difference :year 1
output (sum  product 365 :elapsed
int quotient :elapsed 4
minus int quotient :elapsed 100
int quotient :elapsed 400
int quotient difference product 367 :month 362 12
ifelse lessequal? :month 2 0 ifelse leap? :year -1 -2
:day)
end

; Find the day of the week from a day number; 0 = Sunday through 6 = Saturday
to day_of_week :day_number
output modulo :day_number 7
end

; True if the given day is a Sunday
to sunday? :year :month :day
output equal? 0 day_of_week day_number :year :month :day
end

; Put it all together to answer the question posed in the problem
print filter [sunday? ? 12 25] iseq 2008 2121
bye```
Output:
`2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2101 2107 2112 2118`

## Lua

```require("date")

for year=2008,2121 do
if date(year, 12, 25):getweekday() == 1 then
print(year)
end
end
```
Output:
```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
```

### Without external modules

Same output as above

```local dTab = {day = 25, month = 12}
for year = 2008, 2121 do
dTab.year = year
if os.date("%A", os.time(dTab)) == "Sunday" then
print(year)
end
end
```

## M2000 Interpreter

Str\$( number, format\$) use Visual Basic 6 format

```Print "December 25 is a Sunday in:"
For Year=2008 to 2121 {
if  Str\$(Date("25/12/"+str\$(Year,"")),"w")="1" Then {
Print Year
}
}
\\ is the same with this:
Print "December 25 is a Sunday in:"
For Year=2008 to 2121 {
if  Str\$(Date(str\$(Year,"")+"-12-25"),"w")="1" Then {
Print Year
}
}```
Output:
```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
```

## M4

```divert(-1)

define(`for',
`ifelse(\$#,0,``\$0'',
`ifelse(eval(\$2<=\$3),1,
`pushdef(`\$1',\$2)\$4`'popdef(`\$1')\$0(`\$1',incr(\$2),\$3,`\$4')')')')

dnl  julian day number corresponding to December 25th of given year
define(`julianxmas',
ifelse(eval(\$1%4==0 && (\$1%100!=0 || \$1%400==0)),1,
`define(`jd',incr(jd))')`'jd')

divert

for(`yr',2008,2121,
`ifelse(eval(julianxmas(yr)%7==6),1,`yr ')')```
Output:
```2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2101 2107 2112
2118
```

## Maple

```xmas:= proc()
local i, dt;
for i from 2008 to 2121 by 1 do
dt := Date(i, 12, 25);
if (Calendar:-DayOfWeek(dt) = 1) then
print(i);
end if;
end do;
end proc;

xmas();```
Output:
```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
```

Or simply:

`select(y->Calendar:-DayOfWeek(Date(y,12,25))=1,[\$2008..2121]);`
Output:
`[2011, 2016, 2022, 2033, 2039, 2044, 2050, 2061, 2067, 2072, 2078, 2089, 2095, 2101, 2107, 2112, 2118]`

## Mathematica / Wolfram Language

```Reap[If[DateString[{#,12,25},"DayName"]=="Sunday",Sow[#]]&/@Range[2008,2121]][[2,1]]
```

gives back:

```{2011,2016,2022,2033,2039,2044,2050,2061,2067,2072,2078,2089,2095,2101,2107,2112,2118}
```

## MATLAB / Octave

```  t  = datenum([[2008:2121]',repmat([12,25,0,0,0], 2121-2007, 1)]);
t  = t(strmatch('Sunday', datestr(t,'dddd')), :);
datestr(t,'yyyy')
```

Output:
``` ans =
2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
```

## Maxima

```weekday(year, month, day) := block([m: month, y: year, k],
if m < 3 then (m: m + 12, y: y - 1),
k: 1 + remainder(day + quotient((m + 1)*26, 10) + y + quotient(y, 4)
+ 6*quotient(y, 100) + quotient(y, 400) + 5, 7),
['monday, 'tuesday, 'wednesday, 'thurdsday, 'friday, 'saturday, 'sunday][k]
)\$

sublist(makelist(i, i, 2008, 2121),
lambda([y], weekday(y, 12, 25) = 'sunday));
/* [2011, 2016, 2022, 2033, 2039, 2044, 2050, 2061, 2067, 2072, 2078, 2089, 2095, 2101, 2107, 2112, 2118] */
```

## MiniScript

```import "dateTime"

print "Years between 2008 and 2121 when 25th December falls on Sunday:"
years = []
for year in range(2008, 2121)
date = year + "-12-25"
if dateTime.weekday(date) == 0 then years.push year
end for
print years.join(", ")
```
Output:
```Years between 2008 and 2121 when 25th December falls on Sunday:
2011, 2016, 2022, 2033, 2039, 2044, 2050, 2061, 2067, 2072, 2078, 2089, 2095, 2101, 2107, 2112, 2118
```

## МК-61/52

```П9	7	П7	1	П8	НОП	ИП8	2	2	-
1	0	/	[x]	П6	ИП9	+	1	8	9
9	-	3	6	5	,	2	5	*	[x]
ИП8	ИП6	1	2	*	-	1	4	-	3
0	,	5	9	*	[x]	+	2	9	+
ИП7	+	П4	ИП4	7	/	[x]	7	*	-
x=0	64	ИП9	С/П	ИП9	1	+	П9	БП	06
```

Input: РX: starting year.

Output: the year in which Christmas falls on a Sunday. For example, enter 2008, the first result: 2018 (January 7, 2018 is Sunday).

## Modula-3

Translation of: C

Modula-3 represents time using a (safe) wrapper around the C time interface. Consequently, it suffers from the same problem as C.

```MODULE Yule EXPORTS Main;

IMPORT IO, Fmt, Date, Time;

VAR date: Date.T;
time: Time.T;

BEGIN
FOR year := 2008 TO 2121 DO
date.day := 25;
date.month := Date.Month.Dec;
date.year := year;

TRY
time := Date.ToTime(date);
EXCEPT
| Date.Error =>
IO.Put(Fmt.Int(year) & " is the last year we can specify\n");
EXIT;
END;

date := Date.FromTime(time);

IF date.weekDay = Date.WeekDay.Sun THEN
IO.Put("25th of December " & Fmt.Int(year) & " is Sunday\n");
END;
END;
END Yule.```
Output:
```25th of December 2011 is Sunday
25th of December 2016 is Sunday
25th of December 2022 is Sunday
25th of December 2033 is Sunday
2038 is the last year we can specify
```

## MUMPS

Library: VA Kernel version 22.0
```DOWHOLIDAY
;In what years between 2008 and 2121 will December 25 be a Sunday?
;Uses the VA's public domain routine %DTC (Part of the Kernel) named here DIDTC
NEW BDT,EDT,CHECK,CHKFOR,LIST,I,X,Y
;BDT - the beginning year to check
;EDT - the end year to check
;BDT and EDT are year offsets from the epoch date 1/1/1700
;CHECK - the month and day to look at
;CHKFOR - what day of the week to look for
;LIST - list of years in which the condition is true
;I - the year currently being checked
;X - the date in an "internal" format, for input to DOW^DIDTC
;Y - the output from DOW^DIDTC
SET BDT=308,EDT=421,CHECK="1225",CHKFOR=0,LIST=""
FOR I=BDT:1:EDT SET X=I_CHECK D DOW^DIDTC SET:(Y=0) LIST=\$SELECT(\$LENGTH(LIST):LIST_", ",1:"")_(I+1700)
IF \$LENGTH(LIST)=0 WRITE !,"There are no years that have Christmas on a Sunday in the given range."
IF \$LENGTH(LIST) WRITE !,"The following years have Christmas on a Sunday: ",LIST
KILL BDT,EDT,CHECK,CHKFOR,LIST,I,X,Y
QUIT```

Usage:

```USER>D ^DOW

The following years have Christmas on a Sunday: 2011, 2016, 2022, 2033, 2039, 2044, 2050, 2061, 2067, 2072, 2078, 2089, 2095, 2101, 2107, 2112, 2118
```

## Nanoquery

```import Nanoquery.Util

// loop through the years 2008 through 2121
for year in range(2008, 2121)
if (new(Date,"12/25/" + str(year)).getDayOfWeek() = "Sunday")
println "In " + year + ", December 25th is a Sunday."
end if
end for```

## NetRexx

```/* NetRexx */
options replace format comments java crossref savelog symbols nobinary

yearRanges = [int 2008, 2121]
searchday = ''
cal = Calendar

loop year = yearRanges[0] to yearRanges[1]
cal = GregorianCalendar(year, Calendar.DECEMBER, 25)
dayIndex = cal.get(Calendar.DAY_OF_WEEK)
if dayIndex = Calendar.SUNDAY then searchday = searchday year
end year

say 'Between' yearRanges[0] 'and' yearRanges[1]', Christmas day falls on a Sunday on the following years:'
searchday = searchday.strip.changestr(' ', ',')
say '  'searchday

return```
Output:
```Between 2008 and 2121, Christmas day falls on a Sunday on the following years:
2011,2016,2022,2033,2039,2044,2050,2061,2067,2072,2078,2089,2095,2101,2107,2112,2118
```

### Comparison of Some Common Day-of-Week Algorithms

The following program exercises some common "Day-0f-Week" algorithms to confirm they all arrive at the same result.

```/* NetRexx */
options replace format comments java crossref savelog symbols nobinary

days = 'Monday Tuesday Wednesday Thursday Friday Saturday Sunday'
yearRanges = [int 2008, 2121]

searchday = ''
searchday['index'] = days.wordpos('Sunday')
searchday[0] = 0

algorithmName = ['Java Calendar', 'Zeller[1]', 'Zeller[2]', 'Sakamoto', 'Gauss', 'Keith', 'Babwani']

loop alg = 0 to algorithmName.length - 1
sd = searchday[0] + 1
searchday[0] = sd
searchday['agorithm', sd] = algorithmName[alg]
loop year = yearRanges[0] to yearRanges[1]
select case alg
when 0 then dayIndex = getDaynumJavaLibrary(year, 12, 25)
when 1 then dayIndex = getDaynumZellersCongruenceMethod1(year, 12, 25)
when 2 then dayIndex = getDaynumZellersCongruenceMethod2(year, 12, 25)
when 3 then dayIndex = getDaynumSakamoto(year, 12, 25)
when 4 then dayIndex = getDaynumGauss(year, 12, 25)
when 5 then dayIndex = getDaynumKeith(year, 12, 25)
when 6 then dayIndex = getDaynumBabwani(year, 12, 25)
otherwise nop
end
if dayIndex = searchday['index'] then
searchday[sd] = searchday[sd] year
end year
end alg

-- display results
say 'Between' yearRanges[0] 'and' yearRanges[1]', Christmas day falls on a Sunday in the following years:'
loop r_ = 1 to searchday[0]
searchday[r_] = searchday[r_].strip.changestr(' ', ',')
say searchday['agorithm', r_].right(20)':' searchday[r_]
end r_

return

-- -----------------------------------------------------------------------------
method getDaynumJavaLibrary(Year = int, Month = int, Day = int, iso = Rexx 'Y') public static binary returns int
-- The day-of-week is an integer value where 1 is Sunday, 2 is Monday, ..., and 7 is Saturday
-- For an ISO week date Day-of-Week d (1 = Monday to 7 = Sunday), use d = ((h - 1 + 6) mod 7) + 1

cal = Calendar
jmNumber = [ -
Calendar.JANUARY,   Calendar.FEBRUARY, Calendar.MARCH,    Calendar.APRIL    -
, Calendar.MAY,       Calendar.JUNE,     Calendar.JULY,     Calendar.AUGUST   -
, Calendar.SEPTEMBER, Calendar.OCTOBER,  Calendar.NOVEMBER, Calendar.DECEMBER -
]

mon = jmNumber[Month - 1]
cal = GregorianCalendar(Year, mon, Day)
h   = cal.get(Calendar.DAY_OF_WEEK)

if 'YES'.abbrev(iso.upper, 1) then w = ((h - 1 + 6) // 7) + 1
else w = h

return w

-- -----------------------------------------------------------------------------
method getDaynumZellersCongruenceMethod1(Year = int, Month = int, Day = int, iso = Rexx 'Y') public static returns int
-- DayNum results in an integer in the range 0-6 where 0 represents Monday etc.
-- For an ISO week date add 1

if Month = 1 | Month = 2 then do
Month = Month + 12
Year  = Year - 1
end

MonthFactor = 2 * Month + 3 * (Month + 1) % 5
YearFactor  = Year + Year % 4 - Year % 100 + Year % 400
DayNum      = (Day + MonthFactor + YearFactor) // 7

if 'YES'.abbrev(iso.upper, 1) then d = DayNum + 1
else d = DayNum

return d

-- -----------------------------------------------------------------------------
method getDaynumZellersCongruenceMethod2(Year = int, Month = int, Day = int, iso = Rexx 'Y') public static binary returns int
-- h is the day of the week (0 = Saturday, 1 = Sunday, 2 = Monday, ...)
-- For an ISO week date Day-of-Week d (1 = Monday to 7 = Sunday), use d = ((h + 5) mod 7) + 1

if Month < 3 then do
Month = Month + 12
Year  = Year - 1
end
q = Day
m = Month
Y = Year

h = (q + ((m + 1) * 26 % 10) + Y + (Y % 4) + 6 * (Y % 100) + (Y % 400)) // 7

if 'YES'.abbrev(iso.upper, 1) then d = ((h + 5) // 7) + 1
else d = h

return d

-- -----------------------------------------------------------------------------
method getDaynumSakamoto(y = int, m = int, d = int, iso = Rexx 'Y') public static binary returns int
-- h is the day of the week (0 = Sunday, 1 = Monday, 2 = Tuesday...)
-- For an ISO week date Day-of-Week d (1 = Monday to 7 = Sunday), use d = ((h + 6) mod 7) + 1

t = [int 0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4]
y = y - (m < 3)
h = (y + y % 4 - y % 100 + y % 400 + t[m - 1] + d) // 7

if 'YES'.abbrev(iso.upper, 1) then d = ((h + 6) // 7) + 1
else d = h

return d

-- -----------------------------------------------------------------------------
method getDaynumGauss(Year = int, Month = int, Day = int, iso = Rexx 'Y') public static binary returns int
-- W is week day (0 = Sunday, ..., 6 = Saturday)
-- For an ISO week date Day-of-Week d (1 = Monday to 7 = Sunday), use d = ((h + 6) mod 7) + 1

Year = Year - (Month < 3)
k = double Day
C = double Year % 100
Y = double Year // 100
m = double ((Month + 9) // 12) + 1

W = modulo(int (k + Math.floor(2.6 * m - 0.2) + y + Math.floor(y / 4) + Math.floor(c / 4) - 2 * c), 7)

if 'YES'.abbrev(iso.upper, 1) then h = ((W + 6) // 7) + 1
else h = W

return h

-- -----------------------------------------------------------------------------
method getDaynumKeith(y = int, m = int, d = int, iso = Rexx 'Y') public constant binary returns int
-- W is week day (0 = Sunday, ..., 6 = Saturday)
-- For an ISO week date Day-of-Week d (1 = Monday to 7 = Sunday), use d = ((h + 6) mod 7) + 1

if m < 3 then do
d = d + y
y = y - 1
end
else do
d = d + y - 2
end

h = (23 * m % 9 + d + 4 + y % 4 - y % 100 + y % 400) // 7

if 'YES'.abbrev(iso.upper, 1) then W = ((h + 6) // 7) + 1
else W = h

return W

-- -----------------------------------------------------------------------------
method getDaynumBabwani(Year = int, Month = int, Day = int, iso = Rexx 'Y') public constant binary returns int
-- return dow = Day of week: 0 = Saturday, 1 = Sunday, ... 6 = Friday
-- For an ISO week date Day-of-Week W (1 = Monday to 7 = Sunday), use W = ((dow + 5) mod 7) + 1

y = Year
m = Month
d = Day

dow    = int -- dow stands for day of week
dowfg  = double
fmonth = int
leap   = int

if ((y // 100 == 0) & (y // 400 \= 0)) then  -- leap function 1 for leap & 0 for non-leap
leap = 0
else if (y // 4 == 0) then
leap = 1
else
leap = 0

fmonth = 3 + (2 - leap) * ((m + 2) % (2 * m)) + (5 * m + m % 9) % 2 -- f(m) formula
fmonth = fmonth // 7 -- f(m) is brought in range of 0 to 6

century    = y % 100
lastdigits = y // 100

dowfg = 1.25 * lastdigits + fmonth + d - 2 * (century // 4) -- function of weekday for Gregorian
dow = int dowfg // 7 -- remainder on division by 7

if 'YES'.abbrev(iso.upper, 1) then W = ((dow + 5) // 7) + 1
else W = dow

return W

-- -----------------------------------------------------------------------------
method modulo(N = int, D = int) inheritable static binary returns int
return (D + (N // D)) // D```
Output:
```Between 2008 and 2121, Christmas day falls on a Sunday in the following years:
Java Calendar: 2011,2016,2022,2033,2039,2044,2050,2061,2067,2072,2078,2089,2095,2101,2107,2112,2118
Zeller[1]: 2011,2016,2022,2033,2039,2044,2050,2061,2067,2072,2078,2089,2095,2101,2107,2112,2118
Zeller[2]: 2011,2016,2022,2033,2039,2044,2050,2061,2067,2072,2078,2089,2095,2101,2107,2112,2118
Sakamoto: 2011,2016,2022,2033,2039,2044,2050,2061,2067,2072,2078,2089,2095,2101,2107,2112,2118
Gauss: 2011,2016,2022,2033,2039,2044,2050,2061,2067,2072,2078,2089,2095,2101,2107,2112,2118
Keith: 2011,2016,2022,2033,2039,2044,2050,2061,2067,2072,2078,2089,2095,2101,2107,2112,2118
Babwani: 2011,2016,2022,2033,2039,2044,2050,2061,2067,2072,2078,2089,2095,2101,2107,2112,2118
```

## Nim

```import times

for year in 2008..2121:
if getDayOfWeek(25, mDec, year) == dSun:
stdout.write year, ' '
echo ""
```
Output:
`2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2101 2107 2112 2118 `

## Oberon-2

Works with: oo2c version 2
```MODULE DayOfWeek;
IMPORT NPCT:Dates, Out;
VAR
year: INTEGER;
date: Dates.Date;
BEGIN
FOR year := 2008 TO 2121 DO
date := Dates.NewDate(25,12,year);
IF date.DayOfWeek() = Dates.sunday THEN
Out.Int(date.year,4);Out.Ln
END
END
END DayOfWeek.```
Output:
```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
```
Works with: AOS
```MODULE DaysOfWeek; (** AUTHOR ""; PURPOSE ""; *)

IMPORT
Out := KernelLog, Dates;

PROCEDURE Do*;
VAR
date: Dates.DateTime;
i,y,w,wd: LONGINT;
BEGIN
FOR i := 2008 TO 2121 DO
date.year := i;date.month :=12; date.day := 25;
date.hour := 0;date.minute := 0; date.second := 0;
Dates.WeekDate(date,y,w,wd);
IF wd = 7 THEN Out.Int(i,0);Out.Ln END
END
END Do;

END DaysOfWeek.```
Output:
```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
```

## Objective-C

Works with: GNUstep
Works with: Cocoa
```#import <Foundation/Foundation.h>

int main()
{
@autoreleasepool {
for(NSUInteger i=2008; i<2121; i++)
{
NSCalendarDate *d = [[NSCalendarDate alloc]
initWithYear: i
month: 12
day: 25
hour: 0 minute: 0 second:0
timeZone: [NSTimeZone timeZoneWithAbbreviation:@"CET"] ];
if ( [d dayOfWeek] == 0 )
{
printf("25 Dec %u is Sunday\n", i);
}
}

}
return 0;
}
```
Output:
```25 Dec 2011 is Sunday
25 Dec 2016 is Sunday
25 Dec 2022 is Sunday
25 Dec 2033 is Sunday
25 Dec 2039 is Sunday
25 Dec 2044 is Sunday
25 Dec 2050 is Sunday
25 Dec 2061 is Sunday
25 Dec 2067 is Sunday
25 Dec 2072 is Sunday
25 Dec 2078 is Sunday
25 Dec 2089 is Sunday
25 Dec 2095 is Sunday
25 Dec 2101 is Sunday
25 Dec 2107 is Sunday
25 Dec 2112 is Sunday
25 Dec 2118 is Sunday
```

## OCaml

Translation of: C
```#load "unix.cma"
open Unix

try
for i = 2008 to 2121 do
(* I'm lazy so we'll just borrow the current time
instead of having to set all the fields explicitly *)
let mytime = { (localtime (time ())) with
tm_year  = i - 1900;
tm_mon   = 11;
tm_mday  = 25 } in
try
let _, mytime = mktime mytime in
if mytime.tm_wday = 0 then
Printf.printf "25 December %d is Sunday\n" i
with e ->
Printf.printf "%d is the last year we can specify\n" (i-1);
raise e
done
with _ -> ()
```
Output:

of a run on a 32 bit machine

```25 December 2011 is Sunday
25 December 2016 is Sunday
25 December 2022 is Sunday
25 December 2033 is Sunday
2037 is the last year we can specify
```

### With a dedicated library

Unlike the previous example which only uses the OCaml standard library, here with the OCaml Calendar Library we can go until the year 2121:

```open CalendarLib

let list_make_seq first last =
let rec aux i acc =
if i < first then acc
else aux (pred i) (i::acc)
in
aux last []

let print_date (year, month, day) =
Printf.printf "%d-%02d-%02d\n" year month day

let () =
let years = list_make_seq 2008 2121 in
let years = List.filter (fun year ->
Date.day_of_week (Date.make year 12 25) = Date.Sun) years in
print_endline "December 25 is a Sunday in:";
List.iter (Printf.printf "%d\n") years
```
Output:
```\$ ocaml unix.cma str.cma -I +calendar calendarLib.cma xmas_sundays.ml
December 25 is a Sunday in:
2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118```

## Oforth

```import: date
seqFrom(2008, 2121) filter(#[ 12 25 Date newDate dayOfWeek Date.SUNDAY == ]) .```
Output:
```[2011, 2016, 2022, 2033, 2039, 2044, 2050, 2061, 2067, 2072, 2078, 2089, 2095, 2101, 2107, 2112, 2118]
```

## ooRexx

### Christmas

```date = .datetime~new(2008, 12, 25)
lastdate = .datetime~new(2121, 12, 25)

resultList = .array~new -- our collector of years

-- date objects are directly comparable
loop while date <= lastdate
if date~weekday == 7 then resultList~append(date~year)
-- step to the next year
end

say "Christmas falls on Sunday in the years" resultList~toString("Line", ", ")```
Output:
`Christmas falls on Sunday in the years 2011, 2016, 2022, 2033, 2039, 2044, 2050, 2061, 2067, 2072, 2078, 2089, 2095, 2101, 2107, 2112, 2118`

### Weekday

```/* REXX */
Parse Arg yyyymmdd
If arg(1)='' |,
arg(1)='?' Then Do
Say 'rexx wd yyyymmdd will show which weekday that is'
Exit
End
Parse Var yyyymmdd y +4 m +2 d
wd=.Array~of('Monday','Tuesday','Wednesday','Thursday','Friday','Saturday','Sunday')
dt=.DateTime~new(y,m,d)
say yyyymmdd 'is a' wd[dt~weekday]```
Output:
```H:\>rexx wd ?
rexx wd yyyymmdd will show which weekday that is

H:\>rexx wd 20211206
20211206 is a Monday ```

## PARI/GP

```njd(D) =
{
my (m, y);

if (D[2] > 2, y = D[1]; m = D[2]+1, y = D[1]-1; m = D[2]+13);

(1461*y)\4 + (306001*m)\10000 + D[3] - 694024 + if (100*(100*D[1]+D[2])+D[3] > 15821004, 2 - y\100 + y\400)
}

for (y = 2008, 2121, if (njd([y,12,25]) % 7 == 1, print(y)));```

Output:

```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
```

## Pascal

Library: sysutils
Works with: Free Pascal

See Delphi

## PascalABC.NET

```const Sunday = System.DayOfWeek.Sunday;

begin
(2008..2121).Where(y -> DateTime.Create(y,12,25).DayOfWeek = Sunday).Println
end.
```
Output:
```2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2101 2107 2112 2118
```

## Peloton

```<@ SAI>
<@ ITEFORLI3>2121|2008|
<@ LETVARCAP>Christmas Day|25-Dec-<@ SAYVALFOR>...</@></@>
<@ TSTDOWVARLIT>Christmas Day|1</@>
<@ IFF>
<@ SAYCAP>Christmas Day <@ SAYVALFOR>...</@> is a Sunday</@><@ SAYKEY>__Newline</@>
</@>
</@>
</@>```

```<# suppressimplicitoutput>
<# iterate foriteration literalstring3>2121|2008|
<# let variable capture>Christmas Day|25-Dec-<# say value foriteration>...</#></#>
<# test dayofweek variable literal>Christmas Day|1</#>
<# if>
<# say capture>Christmas Day <# say value foriteration>...</#> is a Sunday</#><# say keyword>__Newline</#>
</#>
</#>

</#>
```
Output:
```Christmas Day 2011 is a Sunday
Christmas Day 2016 is a Sunday
Christmas Day 2022 is a Sunday
Christmas Day 2033 is a Sunday
Christmas Day 2039 is a Sunday
Christmas Day 2044 is a Sunday
Christmas Day 2050 is a Sunday
Christmas Day 2061 is a Sunday
Christmas Day 2067 is a Sunday
Christmas Day 2072 is a Sunday
Christmas Day 2078 is a Sunday
Christmas Day 2089 is a Sunday
Christmas Day 2095 is a Sunday
Christmas Day 2101 is a Sunday
Christmas Day 2107 is a Sunday
Christmas Day 2112 is a Sunday
Christmas Day 2118 is a Sunday```

## Perl

```#! /usr/bin/perl -w

use Time::Local;
use strict;

foreach my \$i (2008 .. 2121)
{
my \$time = timelocal(0,0,0,25,11,\$i);
my (\$s,\$m,\$h,\$md,\$mon,\$y,\$wd,\$yd,\$is) = localtime(\$time);
if ( \$wd == 0 )
{
print "25 Dec \$i is Sunday\n";
}
}

exit 0;
```
Output:
```25 Dec 2011 is Sunday
25 Dec 2016 is Sunday
25 Dec 2022 is Sunday
25 Dec 2033 is Sunday
Day too big - 25195 > 24855
Sec too small - 25195 < 78352
Sec too big - 25195 > 15247
Cannot handle date (0, 0, 0, 25, 11, 2038) at ./ydate.pl line 8
```

Using the DateTime module from CPAN:

```#! /usr/bin/perl -w

use DateTime;
use strict;

foreach my \$i (2008 .. 2121)
{
my \$dt = DateTime->new( year   => \$i,
month  => 12,
day    => 25
);
if ( \$dt->day_of_week == 7 )
{
print "25 Dec \$i is Sunday\n";
}
}

exit 0;
```

or shorter:

```#! /usr/bin/perl -w

use DateTime;
use strict;

for (2008 .. 2121) {
print "25 Dec \$_ is Sunday\n"
if DateTime->new(year => \$_, month => 12, day => 25)->day_of_week == 7;
}

exit 0;
```
Output:
```25 Dec 2011 is Sunday
25 Dec 2016 is Sunday
25 Dec 2022 is Sunday
25 Dec 2033 is Sunday
25 Dec 2039 is Sunday
25 Dec 2044 is Sunday
25 Dec 2050 is Sunday
25 Dec 2061 is Sunday
25 Dec 2067 is Sunday
25 Dec 2072 is Sunday
25 Dec 2078 is Sunday
25 Dec 2089 is Sunday
25 Dec 2095 is Sunday
25 Dec 2101 is Sunday
25 Dec 2107 is Sunday
25 Dec 2112 is Sunday
25 Dec 2118 is Sunday
```

Alternatively in one line using grep (read from right to left):

```#! /usr/bin/perl -w

use DateTime;
use strict;

print join " ", grep { DateTime->new(year => \$_, month => 12, day => 25)->day_of_week == 7 } (2008 .. 2121);

0;
```
Output:
`2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2101 2107 2112 2118`

## Phix

Library: Phix/basics
```-- demo\rosetta\Day_of_the_week.exw
sequence res = {}
for y=2008 to 2121 do
if day_of_week(y,12,25,true)="Sunday" then
res = append(res,y)
end if
end for
?res
```
Output:
```{2011,2016,2022,2033,2039,2044,2050,2061,2067,2072,2078,2089,2095,2101,2107,2112,2118}
```

## PHP

```<?php
for(\$i=2008; \$i<2121; \$i++)
{
\$datetime = new DateTime("\$i-12-25 00:00:00");
if ( \$datetime->format("w") == 0 )
{
echo "25 Dec \$i is Sunday\n";
}
}
?>
```
Output:
```25 Dec 2011 is Sunday
25 Dec 2016 is Sunday
25 Dec 2022 is Sunday
25 Dec 2033 is Sunday
25 Dec 2039 is Sunday
25 Dec 2044 is Sunday
25 Dec 2050 is Sunday
25 Dec 2061 is Sunday
25 Dec 2067 is Sunday
25 Dec 2072 is Sunday
25 Dec 2078 is Sunday
25 Dec 2089 is Sunday
25 Dec 2095 is Sunday
25 Dec 2101 is Sunday
25 Dec 2107 is Sunday
25 Dec 2112 is Sunday
25 Dec 2118 is Sunday
```

## Picat

```go =>
L = [Year : Year in 2008..2121, dow(Year, 12, 25) == 0],
println(L),
println(len=L.length),
nl.

% Day of week, Sakamoto's method
dow(Y, M, D) = R =>
T = [0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4],
if M < 3 then
Y := Y - 1
end,
R = (Y + Y // 4 - Y // 100 + Y // 400 + T[M] + D) mod 7.```
Output:
```[2011,2016,2022,2033,2039,2044,2050,2061,2067,2072,2078,2089,2095,2101,2107,2112,2118]
len = 17```

## PicoLisp

```(for (Y 2008 (>= 2121 Y) (inc Y))
(when (= "Sunday" (day (date Y 12 25)))
(printsp Y) ) )```
Output:
`2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2101 2107 2112 2118`

## Pike

```filter(Calendar.Year(2008)->range(Calendar.Year(2121))->years()->month(12)->day(25), lambda(object day){ return day->week_day()==7; })->year()->format_nice();
```
Output:
``` Result: ({ /* 17 elements */
"2011",
"2016",
"2022",
"2033",
"2039",
"2044",
"2050",
"2061",
"2067",
"2072",
"2078",
"2089",
"2095",
"2101",
"2107",
"2112",
"2118"
})
```

## PL/0

Translation of: GW-BASIC
```var year, month, day, dayofweek;

procedure calcdayofweek;
begin
if month < 3 then
begin
year := year - 1;
month := month + 12
end;
dayofweek := year + year / 4 - year / 100 + year / 400;
dayofweek := dayofweek + day + (153 * month + 8) / 5;
dayofweek := dayofweek - (dayofweek / 7) * 7
end;

begin
month := 12; day := 25;
year := 2007;
while year <= 2122 do
begin
call calcdayofweek;
if dayofweek = 0 then ! year;
year := year + 1
end
end.
```
Output:
```    2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
```

## PL/I

```declare i picture '9999';
do i = 2008 to 2121;
if weekday(days('25Dec' || i, 'DDMmmYYYY')) = 1 then
put skip list ('Christmas day ' || i || ' is a Sunday');
end;```

### PL/I-80

```/* Test of PL/I-80 routine to determine day of the week */

sunday_christmas:
proc options (main);
%replace
sunday by 0;
dcl
(year, w) fixed bin(15);
put skip list ('Christmas will fall on Sunday in these years:');
do year = 2008 to 2121;
w = weekday((year),12,25);
if w = sunday then
put skip edit (year) (f(4));
end;

stop;

/*
*  Return day of week (Sun=0, Mon=1, etc.) for a given
*  yr, mo, da using Zeller's congruence
*/
weekday:
proc (yr, mo, da) returns (fixed bin(15));
dcl (yr, mo, da) fixed bin(15);
dcl (c, y, m, d, z) fixed bin(15);
y = yr;  /* make local copies */
m = mo;
d = da;
if m < 3 then
do;
m = m + 10;
y = y - 1;
end;
else m = m - 2;
c = y / 100;
y = mod(y, 100);
z = (26 * m - 2) / 10;
z = z + d + y + (y/4) + (c/4) - 2 * c + 777;
return (mod(z, 7));
end weekday;

end sunday_christmas;```
Output:
```Christmas will fall on Sunday in these years:
2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
```

## PL/M

Translation of: ALGOL W

which is

Translation of: Fortran
Works with: 8080 PL/M Compiler

... under CP/M (or an emulator)

```100H: /* FIND YEARS WHERE CHRISTMAS DAY FALLS ON A SUNDAY                    */

/* CP/M BDOS SYSTEM CALL AND I/O ROUTINES                                 */
BDOS: PROCEDURE( FN, ARG ); DECLARE FN BYTE, ARG ADDRESS; GOTO 5; END;
PR\$CHAR:   PROCEDURE( C ); DECLARE C BYTE;    CALL BDOS( 2, C );  END;
PR\$STRING: PROCEDURE( S ); DECLARE S ADDRESS; CALL BDOS( 9, S );  END;
PR\$NL:     PROCEDURE;   CALL PR\$CHAR( 0DH ); CALL PR\$CHAR( 0AH ); END;
PR\$NUMBER: PROCEDURE( N ); /* PRINTS A NUMBER IN THE MINIMUN FIELD WIDTH  */
DECLARE V ADDRESS, N\$STR ( 6 )BYTE, W BYTE;
V = N;
W = LAST( N\$STR );
N\$STR( W ) = '\$';
N\$STR( W := W - 1 ) = '0' + ( V MOD 10 );
DO WHILE( ( V := V / 10 ) > 0 );
N\$STR( W := W - 1 ) = '0' + ( V MOD 10 );
END;
CALL PR\$STRING( .N\$STR( W ) );
END PR\$NUMBER;

/* RETURNS THE DAY OF THE WEEK CORRESPONDING To D/M/Y                     */
DAY\$OF\$WEEK: PROCEDURE( D, M, Y )BYTE;
DECLARE ( D, M, Y ) ADDRESS;
DECLARE ( J, K, MM, YY ) ADDRESS;
MM = M;
YY = Y;
IF MM <= 2 THEN DO;
MM = MM + 12;
YY = YY - 1;
END;
J = YY  / 100;
K = YY MOD 100;
RETURN ( D + ( ( MM + 1 ) * 26 ) / 10 + K + K / 4 + J / 4 + 5 * J )
MOD 7;
END DAY\$OF\$WEEK ;

DECLARE ( YEAR, MONTH, DAY, COUNT ) ADDRESS;
CALL PR\$STRING( .'25TH OF DECEMBER IS A SUNDAY IN\$' );CALL PR\$NL;
COUNT = 0;
DO YEAR = 2008 TO 2121;
DAY = DAY\$OF\$WEEK( 25, 12, YEAR );
IF DAY = 1 THEN DO;
CALL PR\$CHAR( ' ' );CALL PR\$NUMBER( YEAR );
IF ( COUNT := COUNT + 1 ) MOD 10= 0 THEN CALL PR\$NL;
END;
END;

EOF```
Output:
```25TH OF DECEMBER IS A SUNDAY IN
2011 2016 2022 2033 2039 2044 2050 2061 2067 2072
2078 2089 2095 2101 2107 2112 2118
```

## PowerShell

```2008..2121 | Where-Object { (Get-Date \$_-12-25).DayOfWeek -eq "Sunday" }
```

### Find Christmas holiday for any day and/or year

```function Get-ChristmasHoliday
{
[CmdletBinding()]
[OutputType([PSCustomObject])]
Param
(
[Parameter(Mandatory=\$false,
ValueFromPipeline=\$true,
ValueFromPipelineByPropertyName=\$true,
Position=0)]
[ValidateRange(1,9999)]
[int[]]
\$Year = (Get-Date).Year
)

Process
{
[datetime]\$christmas = Get-Date \$Year/12/25

switch (\$christmas.DayOfWeek)
{
"Sunday"   {[datetime[]]\$dates = 1..5 | ForEach-Object {\$christmas.AddDays(\$_)}}
}

\$dates | Group-Object  -Property Year |
Select-Object -Property @{Name="Year"     ; Expression={\$_.Name}},
@{Name="DayOfWeek"; Expression={\$christmas.DayOfWeek}},
@{Name="Christmas"; Expression={\$christmas.ToString("MM/dd/yyyy")}},
@{Name="DaysOff"  ; Expression={\$_.Group | ForEach-Object {\$_.ToString("MM/dd/yyyy")}}}
}
}
```

```2008..2121 | Get-ChristmasHoliday | where DayOfWeek -match Su
```
Output:
```Year DayOfWeek Christmas  DaysOff
---- --------- ---------  -------
2011    Sunday 12/25/2011 {12/26/2011, 12/27/2011, 12/28/2011, 12/29/2011...}
2016    Sunday 12/25/2016 {12/26/2016, 12/27/2016, 12/28/2016, 12/29/2016...}
2022    Sunday 12/25/2022 {12/26/2022, 12/27/2022, 12/28/2022, 12/29/2022...}
2033    Sunday 12/25/2033 {12/26/2033, 12/27/2033, 12/28/2033, 12/29/2033...}
2039    Sunday 12/25/2039 {12/26/2039, 12/27/2039, 12/28/2039, 12/29/2039...}
2044    Sunday 12/25/2044 {12/26/2044, 12/27/2044, 12/28/2044, 12/29/2044...}
2050    Sunday 12/25/2050 {12/26/2050, 12/27/2050, 12/28/2050, 12/29/2050...}
2061    Sunday 12/25/2061 {12/26/2061, 12/27/2061, 12/28/2061, 12/29/2061...}
2067    Sunday 12/25/2067 {12/26/2067, 12/27/2067, 12/28/2067, 12/29/2067...}
2072    Sunday 12/25/2072 {12/26/2072, 12/27/2072, 12/28/2072, 12/29/2072...}
2078    Sunday 12/25/2078 {12/26/2078, 12/27/2078, 12/28/2078, 12/29/2078...}
2089    Sunday 12/25/2089 {12/26/2089, 12/27/2089, 12/28/2089, 12/29/2089...}
2095    Sunday 12/25/2095 {12/26/2095, 12/27/2095, 12/28/2095, 12/29/2095...}
2101    Sunday 12/25/2101 {12/26/2101, 12/27/2101, 12/28/2101, 12/29/2101...}
2107    Sunday 12/25/2107 {12/26/2107, 12/27/2107, 12/28/2107, 12/29/2107...}
2112    Sunday 12/25/2112 {12/26/2112, 12/27/2112, 12/28/2112, 12/29/2112...}
2118    Sunday 12/25/2118 {12/26/2118, 12/27/2118, 12/28/2118, 12/29/2118...}
```

Get days off for a random year:

```Get-ChristmasHoliday -Year (2008..2121 | Get-Random)
```
Output:
```Year DayOfWeek Christmas  DaysOff
---- --------- ---------  -------
2110  Thursday 12/25/2110 {12/24/2110, 12/25/2110}
```

Get days off for the current year using the Year property returned by `Get-Date`:

```(Get-Date | Get-ChristmasHoliday).DaysOff
```
Output:
```12/26/2016
12/27/2016
12/28/2016
12/29/2016
12/30/2016
```

Get days off for the current year as `[DateTime]` objects:

```(Get-Date | Get-ChristmasHoliday).DaysOff | Get-Date
```
Output:
```Monday, December 26, 2016 12:00:00 AM
Tuesday, December 27, 2016 12:00:00 AM
Wednesday, December 28, 2016 12:00:00 AM
Thursday, December 29, 2016 12:00:00 AM
Friday, December 30, 2016 12:00:00 AM
```

## Prolog

Works with SWI-Prolog;

```main() :-
christmas_days_falling_on_sunday(2011, 2121, SundayList),
writeln(SundayList).

christmas_days_falling_on_sunday(StartYear, EndYear, SundayList) :-
numlist(StartYear, EndYear, YearRangeList),
include(is_christmas_day_a_sunday, YearRangeList, SundayList).

is_christmas_day_a_sunday(Year) :-
Date = date(Year, 12, 25),
day_of_the_week(Date, DayOfTheWeek),
DayOfTheWeek == 7.```
Output:
```?- main.
[2011,2016,2022,2033,2039,2044,2050,2061,2067,2072,2078,2089,2095,2101,2107,2112,2118]
true.```

## Python

```from calendar import weekday, SUNDAY

[year for year in range(2008, 2122) if weekday(year, 12, 25) == SUNDAY]```
Output:
`[2011, 2016, 2022, 2033, 2039, 2044, 2050, 2061, 2067, 2072, 2078, 2089, 2095, 2101, 2107, 2112, 2118]`

The function `calendar.weekday` accepts all dates between 1/1/1 and 9999/12/31, and uses the proleptic Gregorian calendar before adoption of the Gregorian calendar in 1582. There is no gap between 1582/10/4 and 1582/10/15, as can be seen with `print(calendar.calendar(1582))`.

Or, in terms of datetime:

Works with: Python version 3.7
```'''Days of the week'''

from datetime import date
from itertools import islice

# xmasIsSunday :: Int -> Bool
def xmasIsSunday(y):
'''True if Dec 25 in the given year is a Sunday.'''
return 6 == date(y, 12, 25).weekday()

# main :: IO ()
def main():
'''Years between 2008 and 2121 with 25 Dec on a Sunday'''

xs = list(filter(
xmasIsSunday,
enumFromTo(2008)(2121)
))
total = len(xs)
print(
fTable(main.__doc__ + ':\n\n' + '(Total ' + str(total) + ')\n')(
lambda i: str(1 + i)
)(str)(index(xs))(
enumFromTo(0)(total - 1)
)
)

# GENERIC -------------------------------------------------

# enumFromTo :: (Int, Int) -> [Int]
def enumFromTo(m):
'''Integer enumeration from m to n.'''
return lambda n: list(range(m, 1 + n))

# index (!!) :: [a] -> Int -> a
def index(xs):
'''Item at given (zero-based) index.'''
return lambda n: None if 0 > n else (
xs[n] if (
hasattr(xs, "__getitem__")
) else next(islice(xs, n, None))
)

#  FORMATTING ---------------------------------------------
# fTable :: String -> (a -> String) ->
#                     (b -> String) -> (a -> b) -> [a] -> String
def fTable(s):
'''Heading -> x display function -> fx display function ->
f -> xs -> tabular string.
'''
def go(xShow, fxShow, f, xs):
ys = [xShow(x) for x in xs]
w = max(map(len, ys))
return s + '\n' + '\n'.join(map(
lambda x, y: y.rjust(w, ' ') + ' -> ' + fxShow(f(x)),
xs, ys
))
return lambda xShow: lambda fxShow: lambda f: lambda xs: go(
xShow, fxShow, f, xs
)

# MAIN --
if __name__ == '__main__':
main()```
Output:
```Years between 2008 and 2121 with 25 Dec on a Sunday:

(Total 17)

1 -> 2011
2 -> 2016
3 -> 2022
4 -> 2033
5 -> 2039
6 -> 2044
7 -> 2050
8 -> 2061
9 -> 2067
10 -> 2072
11 -> 2078
12 -> 2089
13 -> 2095
14 -> 2101
15 -> 2107
16 -> 2112
17 -> 2118```

## Quackery

Using Tomohiko Sakamoto's algorithm.

```  [ over 3 < if [ 1 - ]
dup 4 / over +
over 100 / -
swap 400 / +
swap 1 -
[ table
0 3 2 5 0 3
5 1 4 6 2 4 ]
+ + 7 mod ]         is dayofweek ( day month year --> weekday )

say "The 25th of December is a Sunday in: " cr
2121 1+ 2008 - times
[ 25 12 i^ 2008 + dayofweek
0 = if [ i^ 2008 + echo sp ] ]```
Output:
```The 25th of December is a Sunday in:
2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2101 2107 2112 2118 ```

## R

```years <- 2008:2121
xmas <- as.POSIXlt(paste0(years, '/12/25'))
years[xmas\$wday==0]
# 2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2101 2107 2112 2118

# Also:
xmas=seq(as.Date("2008/12/25"), as.Date("2121/12/25"), by="year")
as.numeric(format(xmas[weekdays(xmas)== 'Sunday'], "%Y"))

# Still another solution, using ISOdate and weekdays
with(list(years=2008:2121), years[weekdays(ISOdate(years, 12, 25)) == "Sunday"])

# Or with "subset"
subset(data.frame(years=2008:2121), weekdays(ISOdate(years, 12, 25)) == "Sunday")\$years

# Simply replace "Sunday" with whatever it's named in your country,
# or set locale first, with
Sys.setlocale(cat="LC_ALL", "en")

# Under MS Windows, write instead
Sys.setlocale("LC_ALL", "English")```

## Racket

```#lang racket

(require racket/date)

(define (xmas-on-sunday? year)
(zero? (date-week-day (seconds->date (find-seconds 0 0 12 25 12 year)))))

(for ([y (in-range 2008 2121)] #:when (xmas-on-sunday? y))
(displayln y))```

## Raku

(formerly Perl 6)

Works with: Rakudo version 2010.07

As Perl 5, except `DateTime` is built-in, so you don't need to download a module of that name:

`say join ' ', grep { Date.new(\$_, 12, 25).day-of-week == 7 }, 2008 .. 2121;`

## REBOL

```REBOL [
Title: "Yuletide Holiday"
URL: http://rosettacode.org/wiki/Yuletide_Holiday
]

for y 2008 2121 1 [
d: to-date reduce [y 12 25]
if 7 = d/weekday [prin [y ""]]
]```
Output:
`2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2101 2107 2112 2118`

## Red

```Red []
repeat yy 114 [
d: to-date reduce [25 12 (2007 + yy )]
if 7 = d/weekday [ print d ] ;; 7 = sunday
]
;; or
print "version 2"

d: to-date [25 12 2008]
while [d <= 25/12/2121 ] [
if 7 = d/weekday [
print rejoin [d/day '. d/month '. d/year ]
]
d/year: d/year + 1
]```
Output:
```25-Dec-2011
25-Dec-2016
25-Dec-2022
25-Dec-2033
25-Dec-2039
25-Dec-2044
25-Dec-2050
25-Dec-2061
25-Dec-2067
25-Dec-2072
25-Dec-2078
25-Dec-2089
25-Dec-2095
25-Dec-2101
25-Dec-2107
25-Dec-2112
25-Dec-2118
version 2
25.12.2011
25.12.2016
25.12.2022
25.12.2033
25.12.2039
25.12.2044
25.12.2050
25.12.2061
25.12.2067
25.12.2072
25.12.2078
25.12.2089
25.12.2095
25.12.2101
25.12.2107
25.12.2112
25.12.2118
>>

```

## REXX

### using DATE weekday

The extended   DATE   parameters (arguments 2 and 3) are only supported by the newer REXX interpreters.

```    do year=2008 to 2121
if date('w', year"1225", 's') == 'Sunday'  then say year
end   /*year*/```
output:
```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
```

### using DATE base

The extended DATE parameters (arguments 2 and 3) are only supported by the newer REXX interpreters.

```    do year=2008 to 2121
if date('b', year"1225", 's') // 7 == 6  then say year
end   /*year*/```
output   is identical to the 1st REXX version.

### using DATE iso

Works with Regina REXX only.

The extended   DATE   parameters (arguments 2 and 3) are only supported by the newer REXX interpreters.

Programming note:   The   ISO   option of the   date   BIF is a Regina extension.

Language note:   the DATE   built-in function always returns the day-of-week in English, no matter what the native language is in effect.

```/*REXX program displays in which  years  12/25  (December 25th)   falls on a  Sunday.   */
parse arg start finish .                         /*get the  START  and  FINISH  years.  */
if  start=='' |  start==","  then  start=2008    /*Not specified?  Then use the default.*/
if finish=='' | finish==","  then finish=2121    /* "       "        "   "   "     "    */

do y=start  to finish                      /*process all the years specified.     */

if date('Weekday', y"-12-25", 'ISO')\=='Sunday'  then iterate

/* if date('w'      , y"-12-25", 'i'  ) ···       (same as above).  */
/*          ↑↑↑↑↑↑   ↑↑↑↑↑↑↑↑↑↑  ↑↑↑                                */
/*          option   yyyy-mm-dd  fmt                                */

say 'December 25th,'    y    "falls on a Sunday."
end   /*y*/
/*stick a fork in it,  we're all done. */```
output   when using the default inputs:
```December 25th, 2011 falls on a Sunday.
December 25th, 2016 falls on a Sunday.
December 25th, 2022 falls on a Sunday.
December 25th, 2033 falls on a Sunday.
December 25th, 2039 falls on a Sunday.
December 25th, 2044 falls on a Sunday.
December 25th, 2050 falls on a Sunday.
December 25th, 2061 falls on a Sunday.
December 25th, 2067 falls on a Sunday.
December 25th, 2072 falls on a Sunday.
December 25th, 2078 falls on a Sunday.
December 25th, 2089 falls on a Sunday.
December 25th, 2095 falls on a Sunday.
December 25th, 2101 falls on a Sunday.
December 25th, 2107 falls on a Sunday.
December 25th, 2112 falls on a Sunday.
December 25th, 2118 falls on a Sunday.
```

### old school DOW

This   DOW   (day-of-week)   version will work with any version of a REXX interpreter.

```/*REXX program (old school) displays in which years 12/25 (Dec. 25th) falls on a Sunday.*/
parse arg start finish .                         /*get the  START  and  FINISH  years.  */
if  start=='' |  start==","  then  start=2008    /*Not specified?  Then use the default.*/
if finish=='' | finish==","  then finish=2121    /* "       "        "   "   "     "    */

do y=start  to finish                      /*process all the years specified.     */
if dow(12,25,y)==1  then say 'December 25th,'       y       "falls on a Sunday."
end   /*y*/
exit                                             /*stick a fork in it,  we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
dow: procedure; parse arg m,d,y;                 if m<3  then do;  m= m+12;  y= y-1;  end
yL= left(y, 2);      yr= right(y, 2);  w= (d + (m+1)*26%10 +yr +yr%4 +yL%4 +5*yL) //7
if w==0  then w= 7;  return w               /*Sunday=1,  Monday=2,  ···  Saturday=7*/```
output   when using the default input:
```December 25th, 2011 falls on a Sunday.
December 25th, 2016 falls on a Sunday.
December 25th, 2022 falls on a Sunday.
December 25th, 2033 falls on a Sunday.
December 25th, 2039 falls on a Sunday.
December 25th, 2044 falls on a Sunday.
December 25th, 2050 falls on a Sunday.
December 25th, 2061 falls on a Sunday.
December 25th, 2067 falls on a Sunday.
December 25th, 2072 falls on a Sunday.
December 25th, 2078 falls on a Sunday.
December 25th, 2089 falls on a Sunday.
December 25th, 2095 falls on a Sunday.
December 25th, 2101 falls on a Sunday.
December 25th, 2107 falls on a Sunday.
December 25th, 2112 falls on a Sunday.
December 25th, 2118 falls on a Sunday.
```

## Ring

```for n = 2008 to 2121
if n < 2100 leap = n - 1900 else leap = n - 1904 ok
m = (((n-1900)%7) + floor(leap/4) + 27) % 7
if m = 4 see "25 Dec " + n + nl ok
next```

## RPL

Early RPL versions do not have any date library, so a specific instruction implement Zeller's congruence with a stack-oriented algorithm.

Works with: HP version 28
```≪ IF OVER 2 ≤ THEN 1 - SWAP 12 + SWAP END
100 MOD LAST / FLOOR
DUP 4 / FLOOR SWAP DUP + - SWAP DUP 4 / FLOOR + +
SWAP 1 + 13 * 5 / FLOOR + +
7 MOD 5 + 7 MOD 1 +
≫ 'WKDAY' STO
```

In 1990, RPL gained some basic functions for calculating the date, but nothing for directly obtaining the day of the week.

Works with: HP version 48
```≪ { "MON" TUE" "WED" "THU" "FRI" "SAT" "SUN" }
SWAP 0 TSTR 1 3 SUB POS
≫ 'WKDAY' STO         @   ( dd.mmyyyy → 1..7 )
```
```≪ { } 2008 2121 FOR year
IF 25 12 year WKDAY 7 == THEN year + END NEXT
≫ EVAL
```
Output:
``` 1: { 2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2101 2107 2112 2118 }
```

## Ruby

```require 'date'

(2008..2121).each {|year| puts "25 Dec #{year}" if Date.new(year, 12, 25).sunday? }```
Output:
```25 Dec 2011
25 Dec 2016
25 Dec 2022
25 Dec 2033
25 Dec 2039
25 Dec 2044
25 Dec 2050
25 Dec 2061
25 Dec 2067
25 Dec 2072
25 Dec 2078
25 Dec 2089
25 Dec 2095
25 Dec 2101
25 Dec 2107
25 Dec 2112
25 Dec 2118
```

Or using the Time class

`(2008..2121).each {|year| puts "25 Dec #{year}" if Time.local(year, 12, 25).sunday?}`
Output:
```25 Dec 2011
25 Dec 2016
25 Dec 2022
25 Dec 2033
25 Dec 2039
25 Dec 2044
25 Dec 2050
25 Dec 2061
25 Dec 2067
25 Dec 2072
25 Dec 2078
25 Dec 2089
25 Dec 2095
25 Dec 2101
25 Dec 2107
25 Dec 2112
25 Dec 2118
```

## Rust

```extern crate chrono;

use chrono::prelude::*;

fn main() {
let years = (2008..2121).filter(|&y| Local.ymd(y, 12, 25).weekday() == Weekday::Sun).collect::<Vec<i32>>();
println!("Years = {:?}", years);
}```

Output:

```Years = [2011, 2016, 2022, 2033, 2039, 2044, 2050, 2061, 2067, 2072, 2078, 2089, 2095, 2101, 2107, 2112, 2118]
```

## SAS

```data _null_;
do y=2008 to 2121;
a=mdy(12,25,y);
if weekday(a)=1 then put y;
end;
run;

/* 2011 2016 2022 2033 2039 2044 2050 2061 2067
2072 2078 2089 2095 2101 2107 2112 2118 */```

## Scala

Library: Scala

### JDK (discouraged)

```import java.util.{ Calendar, GregorianCalendar }
import Calendar.{ DAY_OF_WEEK, DECEMBER, SUNDAY }

object DayOfTheWeek extends App {
val years = 2008 to 2121

val yuletide =
years.filter(year => (new GregorianCalendar(year, DECEMBER, 25)).get(DAY_OF_WEEK) == SUNDAY)

// If you want a test: (optional)
assert(yuletide ==
Seq(2011, 2016, 2022, 2033, 2039, 2044, 2050, 2061,
2067, 2072, 2078, 2089, 2095, 2101, 2107, 2112, 2118))

println(yuletide.mkString(
s"\${yuletide.length} Years between \${years.head} and \${years.last}" +
" including where Christmas is observed on Sunday:\n", ", ", "."))
}```

### JDK >= 8 (recommended)

#### Naive programming

```import java.time.{ DayOfWeek, LocalDate }

object DayOfTheWeek1 extends App {
val years = 2008 to 2121
val yuletide = for {
year <- years
if LocalDate.of(year, 12, 25).getDayOfWeek() == DayOfWeek.SUNDAY
} yield year

println(yuletide.mkString(
s"\${yuletide.count(p => true)} Years between \${years.head} and \${years.last}" +
" including where Christmas is observed on Sunday:\n", ", ", "."))
}```

#### Idiomatic programming

```import java.time.{ DayOfWeek, LocalDate }

object DayOfTheWeek1 extends App {
val years = 2008 to 2121
val yuletide =
years.filter(year => (LocalDate.of(year, 12, 25).getDayOfWeek() == DayOfWeek.SUNDAY))

// If you want a test: (optional)
assert(yuletide ==
Seq(2011, 2016, 2022, 2033, 2039, 2044, 2050, 2061,
2067, 2072, 2078, 2089, 2095, 2101, 2107, 2112, 2118))

println(yuletide.mkString(
s"\${yuletide.length} Years between \${years.head} and \${years.last}" +
" including where Christmas is observed on Sunday:\n", ", ", "."))
}```

#### Tail recursion

```import java.time.{ DayOfWeek, LocalDate }
import scala.annotation.tailrec

object DayOfTheWeek3 extends App {
val years = 2008 to 2121
val yuletide = {
@tailrec
def inner(anni: List[Int], accu: List[Int]): List[Int] = {
if (anni == Nil) accu
else inner(anni.tail, accu ++
else Nil))
}
inner(years.toList, Nil)
}

// If you want a test: (optional)
assert(yuletide ==
Seq(2011, 2016, 2022, 2033, 2039, 2044, 2050, 2061,
2067, 2072, 2078, 2089, 2095, 2101, 2107, 2112, 2118))

println(yuletide.mkString(
s"\${yuletide.length} Years between \${years.head} and \${years.last}" +
" including where Christmas is observed on Sunday:\n", ", ", "."))
}```
Output of all solutions:
```Years between 2008 and 2121 including when Christmas is observed on Sunday:
2011, 2016, 2022, 2033, 2039, 2044, 2050, 2061, 2067, 2072, 2078, 2089, 2095, 2101, 2107, 2112, 2118.```

## Scheme

```(define (day-of-week year month day)
(if (< month 3)
(begin (set! month (+ month 12)) (set! year (- year 1))))
(+ 1
(remainder (+ 5 day (quotient (* (+ 1 month) 13) 5)
year (quotient year 4) (* (quotient year 100) 6) (quotient year 400))
7)))

(let loop ((y 2121) (v '()))
(if (< y 2008)
v
(loop (- y 1)
(if (= 7 (day-of-week y 12 25))
(cons y v)
v)))))

; (2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2101 2107 2112 2118)```

## Seed7

The library time.s7i defines the function dayOfWeek, which returns 1 for monday, 2 for tuesday, and so on up to 7 for sunday.

```\$ include "seed7_05.s7i";
include "time.s7i";

const proc: main is func
local
var integer: year is 0;
begin
for year range 2008 to 2122 do
if dayOfWeek(date(year, 12, 25)) = 7 then
writeln("Christmas comes on a sunday in " <& year);
end if;
end for;
end func;```
Output:
```Christmas comes on a sunday in 2011
Christmas comes on a sunday in 2016
Christmas comes on a sunday in 2022
Christmas comes on a sunday in 2033
Christmas comes on a sunday in 2039
Christmas comes on a sunday in 2044
Christmas comes on a sunday in 2050
Christmas comes on a sunday in 2061
Christmas comes on a sunday in 2067
Christmas comes on a sunday in 2072
Christmas comes on a sunday in 2078
Christmas comes on a sunday in 2089
Christmas comes on a sunday in 2095
Christmas comes on a sunday in 2101
Christmas comes on a sunday in 2107
Christmas comes on a sunday in 2112
Christmas comes on a sunday in 2118
```

## SenseTalk

```// In what years between 2008 and 2121 will the 25th of December be a Sunday?

repeat with year = 2008 to 2121
set Christmas to "12/25/" & year
if the WeekDayName of Christmas is Sunday then
put "Christmas in " & year & " falls on a Sunday"
end if
end repeat```
Output:
```Christmas in 2011 falls on a Sunday
Christmas in 2016 falls on a Sunday
Christmas in 2022 falls on a Sunday
Christmas in 2033 falls on a Sunday
Christmas in 2039 falls on a Sunday
Christmas in 2044 falls on a Sunday
Christmas in 2050 falls on a Sunday
Christmas in 2061 falls on a Sunday
Christmas in 2067 falls on a Sunday
Christmas in 2072 falls on a Sunday
Christmas in 2078 falls on a Sunday
Christmas in 2089 falls on a Sunday
Christmas in 2095 falls on a Sunday
Christmas in 2101 falls on a Sunday
Christmas in 2107 falls on a Sunday
Christmas in 2112 falls on a Sunday
Christmas in 2118 falls on a Sunday
```

## Sidef

Translation of: Perl
```require('Time::Local')

for year in (2008 .. 2121) {
var time = %S<Time::Local>.timelocal(0,0,0,25,11,year)
var wd = Time(time).local.wday
if (wd == 0) {
say "25 Dec #{year} is Sunday"
}
}```
Output:
```25 Dec 2011 is Sunday
25 Dec 2016 is Sunday
25 Dec 2022 is Sunday
25 Dec 2033 is Sunday
25 Dec 2039 is Sunday
25 Dec 2044 is Sunday
25 Dec 2050 is Sunday
25 Dec 2061 is Sunday
25 Dec 2067 is Sunday
25 Dec 2072 is Sunday
25 Dec 2078 is Sunday
25 Dec 2089 is Sunday
25 Dec 2095 is Sunday
25 Dec 2101 is Sunday
25 Dec 2107 is Sunday
25 Dec 2112 is Sunday
25 Dec 2118 is Sunday
```

## Simula

Translation of: Sinclair ZX81 BASIC
```BEGIN
INTEGER M,D,Y;
M := 12;
D := 25;
FOR Y := 2008 STEP 1 UNTIL 2121 DO BEGIN
INTEGER W,A,MM,YY;
A := (14 - M)//12;
MM := M + 12*A - 2;
YY := Y - A;
W := D + ((13*MM - 1)//5) + YY + (YY//4) - (YY//100) + (YY//400);
W := MOD(W,7);
IF W = 0 THEN
BEGIN OUTINT(Y,0);
OUTIMAGE;
END;
END;
END.```
Output:
```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118```

## Smalltalk

```2008 to: 2121 do: [ :year | |date|
date := Date newDay: 25 monthIndex: 12 year: year.
date dayName = #Sunday
ifTrue: [ date displayNl ]
]```
Output:
```25-Dec-2011
25-Dec-2016
25-Dec-2022
25-Dec-2033
25-Dec-2039
25-Dec-2044
25-Dec-2050
25-Dec-2061
25-Dec-2067
25-Dec-2072
25-Dec-2078
25-Dec-2089
25-Dec-2095
25-Dec-2101
25-Dec-2107
25-Dec-2112
25-Dec-2118```

## SparForte

As a structured script.

```#!/usr/local/bin/spar
pragma annotate( summary, "yuletide" );
pragma annotate( description, "A company decides that whenever Xmas falls on a Sunday they will give their" );
pragma annotate( description, "workers all extra paid holidays so that, together with any public holidays," );
pragma annotate( description, "workers will not have to work the following week (between the 25th of" );
pragma annotate( description, "December and the first of January)." );
pragma annotate( description, "");
pragma annotate( description, "In what years between 2008 and 2121 will the 25th of December be a Sunday?" );
pragma annotate( description, "");
pragma annotate( description, "Using any standard date handling libraries of your programming language;" );
pragma annotate( description, "compare the dates calculated with the output of other languages to discover" );
pragma annotate( description, "any anomalies in the handling of dates which may be due to, for example," );
pragma annotate( description, "overflow in types used to represent dates/times similar to y2k type" );
pragma annotate( description, "problems. ");
pragma annotate( see_also, "http://rosettacode.org/wiki/Day_of_the_week" );
pragma annotate( author, "Ken O. Burtch ");

pragma restriction( no_external_commands );

procedure yuletide is
begin
for Year in 2008..2121 loop
if calendar.day_of_week ( calendar.time_of (Year, 12, 25, 0)) = 1 then
put_line( "Christmas " & strings.image( Year ) & " is on a Sunday" );
end if;
end loop;
end yuletide;```

## SQL

### Oracle

SQL has good support for date functions; care must be taken with NLS settings (globalization support), in the code below the date format language is passed in as an argument to the relevant function. (Or, see a variation that does not depend on language settings, after the output shown below.)

```select extract(year from dt) as year_with_xmas_on_sunday
from   (
select  add_months(date '2008-12-25', 12 * (level - 1)) as dt
from    dual
connect by level <= 2121 - 2008 + 1
)
where  to_char(dt, 'Dy', 'nls_date_language=English') = 'Sun'
order  by 1
;```

Output:
```YEAR_WITH_XMAS_ON_SUNDAY
------------------------
2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118

17 rows selected.```

Alternatively, the WHERE clause can be written in a way that avoids the complication of language settings. The (overloaded) TRUNC function, as applied to dates, takes a second argument indicating "to what" we must truncate. One option is 'iw' for "ISO week"; this truncates to the most recent Monday (the beginning of the ISO standard week, which is Monday through Sunday by definition). Like so (replace in the query above):

`where dt - trunc(dt, 'iw') = 6`

### SQLite3

```WITH RECURSIVE cte AS (
SELECT DATE('2008-12-25', '+'||(12*0)||' months') as dt, 1 AS level
UNION  ALL
SELECT DATE('2008-12-25', '+'||(12*level)||' months') as dt, c.level + 1
FROM   cte c
WHERE c.level <= 2121 - 2008 + 1
)
SELECT strftime('%Y', dt)
FROM   cte
where  strftime('%w', dt) = '0';```

### PostgreSQL

``` WITH RECURSIVE cte AS (
SELECT  date '2008-12-25' + interval '12 month' * 0 as dt, 1 AS level
UNION  ALL
SELECT date '2008-12-25' + interval '12 month' * level as dt, c.level + 1
FROM   cte c
WHERE c.level <= 2121 - 2008 + 1
)
SELECT dt
FROM   cte
where  to_char(dt, 'Dy') = 'Sun';```

## Standard ML

```(* Call:  yearsOfSundayXmas(2008, 2121)   *)
fun yearsOfSundayXmas(fromYear, toYear) =
if fromYear>toYear then
()
else
let
val d = Date.date {year=fromYear, month=Date.Dec, day=25,
hour=0, minute=0, second=0,
offset=SOME Time.zeroTime}
val wd = Date.weekDay d
in
if wd=Date.Sun then
(
print(Int.toString fromYear ^ "\n");
yearsOfSundayXmas(fromYear+1, toYear)
)
else
yearsOfSundayXmas(fromYear+1, toYear)
end;```
Output:
```- yearsOfSundayXmas(2008, 2121);
2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118```

## Stata

The `dow()` function returns the day of week, where sunday is zero and saturday is 6.

```clear
sca n=2121-2008+1
set obs `=n'
gen year=2007+_n
list if dow(mdy(12,25,year))==0, noobs sep(0)

+------+
| year |
|------|
| 2011 |
| 2016 |
| 2022 |
| 2033 |
| 2039 |
| 2044 |
| 2050 |
| 2061 |
| 2067 |
| 2072 |
| 2078 |
| 2089 |
| 2095 |
| 2101 |
| 2107 |
| 2112 |
| 2118 |
+------+```

### Mata

```year=2008::2121
select(year,dow(mdy(12,25,year)):==0)```

## Suneido

```year = 2008
while (year <= 2121)
{
if Date('#' \$ year \$ '1225').WeekDay() is 0
Print(year)
++year
}```
Output:
```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118```

## Swift

```import Cocoa

var year=2008
let formatter=DateFormatter()
formatter.dateFormat = "yyyy-MM-dd"

let gregorian:NSCalendar! = NSCalendar(calendarIdentifier: NSCalendar.Identifier.gregorian)
while (year<2122){
var date:NSDate!=formatter.date(from: String(year)+"-12-25") as NSDate?
var components=gregorian.components(NSCalendar.Unit.weekday, from: date as Date)
var dayOfWeek:NSInteger=components.weekday!
if(dayOfWeek==1){
print(year)
}
year+=1
}```
Output:
```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118```

## Tcl

Works with: Tcl version 8.5
```package require Tcl 8.5

for {set y 2008} {\$y <= 2121} {incr y} {
if {[clock format [clock scan "\$y-12-25" -format {%Y-%m-%d}] -format %w] == 0} {
puts "xmas \$y is a sunday"
}
}```
Output:
```xmas 2011 is a sunday
xmas 2016 is a sunday
xmas 2022 is a sunday
xmas 2033 is a sunday
xmas 2039 is a sunday
xmas 2044 is a sunday
xmas 2050 is a sunday
xmas 2061 is a sunday
xmas 2067 is a sunday
xmas 2072 is a sunday
xmas 2078 is a sunday
xmas 2089 is a sunday
xmas 2095 is a sunday
xmas 2101 is a sunday
xmas 2107 is a sunday
xmas 2112 is a sunday
xmas 2118 is a sunday```

## TUSCRIPT

```\$\$ MODE TUSCRIPT
PRINT "25th of December will be a Sunday in the following years: "
LOOP year=2008,2121
SET dayofweek = DATE (number,25,12,year,nummer)
IF (dayofweek==7) PRINT year
ENDLOOP```
Output:
```25th of December will be a Sunday in the following years:
2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
```

## TypeScript

Translation of: Minimal BASIC
```// Find years with Sunday Christmas
var f = 2008;
var t = 2121;
console.log(`Sunday Christmases \${f} - \${t}`);
for (y = f; y <= t; y++) {
var x = (y * 365) + Math.floor(y / 4) - Math.floor(y / 100) + Math.floor(y / 400) - 6;
if (x % 7 == 0)
process.stdout.write(`\${y}\t`);
}
process.stdout.write("\n");```
Output:
```Sunday Christmases 2008 - 2121
2011	2016	2022	2033	2039	2044	2050	2061	2067	2072	2078	2089	2095	2101	2107	2112	2118
```

## UNIX Shell

Unix commands may use time_t to count seconds since the epoch. For systems with 32-bit time, the counter overflows during 19 January 2038. These scripts continue to 2121 and may need a system with 64-bit time, to prevent the overflow.

### With GNU date

This solution uses date -d, which seems to be a GNU extension, so it only works with those systems.

Works with: bash
```#! /bin/bash

for (( i=2008; i<=2121; ++i ))
do
date -d "\$i-12-25"
done  |grep Sun

exit 0```

The first lines of output (from a GNU/Linux system with 32bit time_t, date version 6.9) are

```Sun Dec 25 00:00:00 CET 2011
Sun Dec 25 00:00:00 CET 2016
Sun Dec 25 00:00:00 CET 2022
Sun Dec 25 00:00:00 CET 2033
date: invalid date `2038-12-25'```

I.e., starting from year 2038, the date command (which uses the glibc library, at least on GNU systems), is not able to recognise the date as a valid one!

Different machine/OS version (64 bit time_t): This is the same command run on RedHat Linux.

```bash-3.00\$ date --version
date (coreutils) 5.2.1
Written by David MacKenzie.

Copyright (C) 2004 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
bash-3.00\$ uname -a
Linux brslln01 2.6.9-67.ELsmp #1 SMP Wed Nov 7 13:56:44 EST 2007 x86_64 x86_64 x86_64 GNU/Linux
bash-3.00\$ for((i=2009; i <= 2121; i++)); do  date -d "\$i-12-25" |egrep Sun; done
Sun Dec 25 00:00:00 GMT 2011
Sun Dec 25 00:00:00 GMT 2016
Sun Dec 25 00:00:00 GMT 2022
Sun Dec 25 00:00:00 GMT 2033
Sun Dec 25 00:00:00 GMT 2039
Sun Dec 25 00:00:00 GMT 2044
Sun Dec 25 00:00:00 GMT 2050
Sun Dec 25 00:00:00 GMT 2061
Sun Dec 25 00:00:00 GMT 2067
Sun Dec 25 00:00:00 GMT 2072
Sun Dec 25 00:00:00 GMT 2078
Sun Dec 25 00:00:00 GMT 2089
Sun Dec 25 00:00:00 GMT 2095
Sun Dec 25 00:00:00 GMT 2101
Sun Dec 25 00:00:00 GMT 2107
Sun Dec 25 00:00:00 GMT 2112
Sun Dec 25 00:00:00 GMT 2118
bash-3.00\$```

### With GNU date and GNU seq (UnixPipes)

Like the previous solution, this solution uses date -d, which seems to be a GNU extension. Output is same as previous solution.

`seq 2008 2121 | xargs -IYEAR -n 1 date +%c -d 'Dec 25 YEAR' | grep Sun`

### With Unix cal

The `cal` command is a tradition since Version 6 AT&T UNIX. This solution assumes that `cal` will always output a calendar in this format.

```\$ cal 12 2011
December 2011
Su Mo Tu We Th Fr Sa
1  2  3
4  5  6  7  8  9 10
11 12 13 14 15 16 17
18 19 20 21 22 23 24
25 26 27 28 29 30 31
```

This format always puts Sunday in columns 1 and 2. The solution uses tail to delete the first 2 lines (month, year, names of days), cut to extract Sunday's columns, and grep to check if "25" appears in those columns.

Works with: Bourne Shell
```y=2008
while test \$y -lt 2122; do
cal 12 \$y | tail +3 | cut -c1-2 | grep -Fq 25 && echo 25 Dec \$y
y=`expr \$y + 1`
done```

Running this script with OpenBSD, the output is identical to the C# program. OpenBSD cal accepts any year from 1 to 9999, so 2008 to 2122 is well within range.

### With zsh

```zmodload zsh/datetime
for (( year = 2010; year <= 2121; year++ ));
if [[ \$(strftime '%A' \$(strftime -r '%F' \$year-12-25)) == Sunday ]] print \$year```

If the system has 32-bit time, this script will malfunction for years >= 2038; it will print no year from 2038 to 2121 (unless today is Sunday, then it prints every year from 2038 to 2121). This happens because strftime -r '%F' \$year-12-25 yields -1 for an out-of-range date, and strftime '%A' -1 yields name of today.

## Ursala

A standard library, `stt`, provides basic date manipulation functions, and is imported in this example. Unix era times denominated in seconds since 1969 (excluding leap seconds) are represented as natural numbers with unlimited precision. Results are valid for the arbitrarily distant future assuming the Gregorian calendar remains in effect.

The algorithm relies on the `string_to_time` function converting a date expressed as a character string to seconds without needing a weekday field in the input, and the `time_to_string` function outputting the corresponding date with the weekday included. The output is then filtered for Sundays.

```#import std
#import nat
#import stt

christmases = time_to_string* string_to_time*TS 'Dec 25 0:0:0 '-*@hS %nP* nrange/2008 2121

#show+

sunday_years = ~&zS sep` * =]'Sun'*~ christmases```
Output:
```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118```

## Vedit macro language

```Buf_Switch(Buf_Free)
for (#3 = 2008; #3 < 2122; #3++) {
Reg_Set(10, "12/25/")
Num_Str(#3, 10, LEFT+APPEND)
if (JDate(@10) % 7 == 0) {
Num_Ins(#3, NOCR)
}
}```
Output:
```2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2101 2107 2112 2118
```

## Visual Objects

```local i as dword

for i := 2008 upto 2121
if DOW(ConDate(i, 12, 25)) = 1
? AsString(i)
endif
next i```
Output:
```2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2101 2107 2112 2118
```

## V (Vlang)

Updated for Vlang version 0.2.2

```import time

fn main() {
for year := 2008; year <= 2121; year++ {
date := time.parse('\${year}-12-25 00:00:00') or { continue }
if date.long_weekday_str() == 'Sunday' {
println('December 25 \${year} is a \${date.long_weekday_str()}')
}
}
}```
Output:
```December 25 2011 is a Sunday
December 25 2016 is a Sunday
December 25 2022 is a Sunday
December 25 2033 is a Sunday
December 25 2039 is a Sunday
December 25 2044 is a Sunday
December 25 2050 is a Sunday
December 25 2061 is a Sunday
December 25 2067 is a Sunday
December 25 2072 is a Sunday
December 25 2078 is a Sunday
December 25 2089 is a Sunday
December 25 2095 is a Sunday
December 25 2101 is a Sunday
December 25 2107 is a Sunday
December 25 2112 is a Sunday
December 25 2118 is a Sunday
```

## VTL-2

Translation of: ALGOL W

...which is

Translation of: Fortran

VTL-2 does not have operator precedence - all expressions are evaluated left-to-right, except for expressions nested in parenthesis, hence the expression at line 1090 differs from that in the Algol W sample.

```1000 #=2000
1010 R=!
1020 N=M
1030 X=Y
1040 #=N>3*1070
1050 N=N+12
1060 X=X-1
1070 J=X/100
1080 K=%
1090 W=N+1*26/10+D+K+(K/4)+(J/4)+(5*J)/7*0+%
1100 #=R
2000 ?="25th of December is a Sunday in";
2010 Y=2008
2020 M=12
2030 D=25
2040 #=1010
2050 #=W=1=0*2080
2060 \$=32
2070 ?=Y
2080 Y=Y+1
2090 #=Y<2121*2040
2100 ?=""```
Output:
```25th of December is a Sunday in 2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2101 2107 2112 2118
```

## Wortel

`!-&y = 0 `.getDay. @new Date[y 11 25] @range[2008 2121]`

Returns:

`[2011 2016 2022 2033 2039 2044 2050 2061 2067 2072 2078 2089 2095 2101 2107 2112 2118]`

## Wren

Library: Wren-date
```import "./date" for Date

System.print("Years between 2008 and 2121 when 25th December falls on Sunday:")
for (year in 2008..2121) {
if (Date.new(year, 12, 25).dayOfWeek == 7) System.print(year)
}```
Output:
```Years between 2008 and 2121 when 25th December falls on Sunday:
2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
```

## XPL0

The original routine in the library only worked correctly between the years 1980 and 2099. It was upgraded with this new routine that handles all dates in the Gregorian calendar, from 1583 onward. It's based on Zeller's Congruence.

```include c:\cxpl\codes;                  \intrinsic 'code' declarations

func    WeekDay(Year, Month, Day);      \Return day of week (0=Sat 1=Sun..6=Fri)
int     Year, Month, Day;
[if Month<=2 then [Month:= Month+12;  Year:= Year-1];
return rem((Day + (Month+1)*26/10 + Year + Year/4 + Year/100*6 + Year/400) / 7);
];      \WeekDay

int     Year;
[for Year:= 2008 to 2121 do
if WeekDay(Year, 12, 25) = 1 then   \25th of December is a Sunday
[IntOut(0, Year);  CrLf(0)];
]```
Output:
```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
```

## zkl

ISO dates, monday is 1, sunday is 7

```var [const] D=Time.Date;
foreach y in ([2008..2121]){
if (D.Sunday==D.weekDay(y,12,25)) println(y)
}```

Or, in a more functional manner:

```var [const] D=Time.Date;
[2008..2121].filter(fcn(y){ D.Sunday==D.weekDay(y,12,25) }).println()```
Output:
```2011
2016
2022
2033
2039
2044
2050
2061
2067
2072
2078
2089
2095
2101
2107
2112
2118
```

## zonnon

```module Main;
```2017-12-05 :Tuesday