# Day of the week of Christmas and New Year

Determine programatically and show on this page on what weekday Christmas Day, 2021 and New Year's Day, 2022 will fall or did fall.

*is a*

**Day of the week of Christmas and New Year****draft**programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

- Task

## 11l

```
V weekDays = [‘Sunday’, ‘Monday’, ‘Tuesday’, ‘Wednesday’, ‘Thursday’, ‘Friday’, ‘Saturday’]
V thisXMas = Time(2021, 12, 25)
V thisXMasDay = Int(thisXMas.strftime(‘%w’))
V thisXMasDayAsString = weekDays[thisXMasDay]
print(‘This year's Christmas is on a ’thisXMasDayAsString)
V nextNewYear = Time(2022, 1, 1)
V nextNewYearDay = Int(nextNewYear.strftime(‘%w’))
V nextNewYearDayAsString = weekDays[nextNewYearDay]
print(‘Next new year is on a ’nextNewYearDayAsString)
```

- Output:

This year's Christmas is on a Saturday Next new year is on a Saturday

## Ada

```
with Ada.Text_Io;
with Ada.Calendar.Formatting;
procedure Weekdays is
use Ada.Text_Io;
use Ada.Calendar.Formatting;
subtype Time is Ada.Calendar.Time;
procedure Info (Date : Time) is
begin
Put (Image (Date));
Put (" is a ");
Put (Day_Name'Image (Day_Of_Week (Date)));
Put (".");
New_Line;
end Info;
Christmas_Day : constant Time := Time_Of (Year => 2021, Month => 12, Day => 25);
New_Years_Day : constant Time := Time_Of (Year => 2022, Month => 01, Day => 01);
begin
Info (Christmas_Day);
Info (New_Years_Day);
end Weekdays;
```

- Output:

2021-12-25 00:00:00 is a SATURDAY. 2022-01-01 00:00:00 is a SATURDAY.

## ALGOL 68

```
BEGIN # find the day of the week 25/12/2021 and 01/01/2022 fall on #
[]STRING day name =
[]STRING( "Saturday", "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday" )[ AT 0 ];
PROC day of week = ( INT d, m, y )INT:
BEGIN
INT mm := m;
INT yy := y;
IF mm <= 2 THEN
mm +:= 12;
yy -:= 1
FI;
INT j = yy OVER 100;
INT k = yy MOD 100;
( d + ( ( mm + 1 ) * 26 ) OVER 10 + k + k OVER 4 + j OVER 4 + 5 * j ) MOD 7
END # day of week # ;
print( ( "25th of December 2021 is a ", day name[ day of week( 25, 12, 2021 ) ], newline ) );
print( ( " 1st of January 2022 is a ", day name[ day of week( 1, 1, 2022 ) ], newline ) )
END
```

- Output:

25th of December 2021 is a Saturday 1st of January 2022 is a Saturday

## ALGOL W

Re-using code from the Day of the week task.

```
begin % find the day of the week 25/12/2021 and 01/01/2022 fall on %
string(10) array dayName( 0 :: 6 );
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;
dayName( 0 ) := "Saturday"; dayName( 1 ) := "Sunday"; dayName( 2 ) := "Monday";
dayName( 3 ) := "Tuesday"; dayName( 4 ) := "Wednesday"; dayName( 5 ) := "Thursday";
dayName( 6 ) := "Friday";
write( "25th of December 2021 is a ", dayName( Day_of_week( 25, 12, 2021 ) ) );
write( " 1st of January 2022 is a ", dayName( Day_of_week( 1, 1, 2022 ) ) )
end.
```

- Output:

25th of December 2021 is a Saturday 1st of January 2022 is a Saturday

## AutoHotkey

```
FormatTime, xmas , 20211225, dddd
FormatTime, newYear , 20220101, dddd
MsgBox % result := "Christmas Day, 2021 : " xmas "`nNew Year's Day, 2022 : " newYear
```

- Output:

Christmas Day, 2021 : Saturday New Year's Day, 2022 : Saturday

## AWK

```
# syntax: GAWK -f WHAT_WEEKDAYS_WILL_CHRISTMAS_AND_NEW_YEAR.AWK
BEGIN {
fmt = "%Y-%m-%d is a %A"
print(strftime(fmt,mktime("2021 12 25 0 0 0")))
print(strftime(fmt,mktime("2022 01 01 0 0 0")))
print("")
fmt = "%d %b %Y is %A"
print(strftime(fmt,mktime("2021 12 25 0 0 0")))
print(strftime(fmt,mktime("2022 01 01 0 0 0")))
exit(0)
}
```

- Output:

2021-12-25 is a Saturday 2022-01-01 is a Saturday 25 Dec 2021 is Saturday 01 Jan 2022 is Saturday

## BASIC

```
10 DEFINT A-Z
20 DIM D$(6)
30 FOR I=0 TO 6: READ D$(I): NEXT
40 FOR I=1 TO 2
50 READ Y,M,D
60 PRINT USING "##/##/#### is a ";M;D;Y;
70 IF M<=2 THEN M=M+12: Y=Y-1
80 J=Y\100
90 K=Y MOD 100
100 D=(D+((M+1)*26)\10+K+K\4+J\4+5*J) MOD 7
110 PRINT D$(D)
120 NEXT
130 DATA Saturday,Sunday,Monday,Tuesday,Wednesday,Thursday,Friday
140 DATA 2021,12,25
150 DATA 2022,1,1
```

- Output:

12/25/2021 is a Saturday 1/ 1/2022 is a Saturday

### BASIC256

```
print "Christmas Day 2021 is on a "; diasemana$(2021, 12, 25)
print "New Year's Day 2022 is on a "; diasemana$(2022, 1, 1)
end
function diasemana$(anno, mes, dia)
dim nombre$(6)
nombre$ = {"Saturday", "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday"}
if mes <= 2 then
mes += 12
anno -= 1
end if
dia = (dia-1 + ((mes+1)*26)\10 + anno + anno\4 + anno\400 + anno*6\100) mod 7
return nombre$[dia]
end function
```

### Chipmunk Basic

```
100 REM Day of the week of Christmas and New Year
110 CLS
120 DIM d$(6)
130 FOR i = 0 TO 6 : READ d$(i) : NEXT i
140 FOR i = 1 TO 2
150 READ y,m,d
160 PRINT m;"/";d;"/";y;" is a ";
170 IF m <= 2 THEN LET m = m+12 : LET y = y-1
180 LET j = INT(y/100)
190 LET k = y-INT(y/100)*100
200 LET t = (d+INT((m+1)*26)/10+k+k/4+j/4+5*j)
210 LET d = t-INT(t/7)*7
211 rem LET d = INT(d + ((m + 1) * 26) / 10 + K + K / 4 + J \ 4 + 5 * J) MOD 7
220 PRINT d$(d)
230 NEXT i
240 DATA "Saturday","Sunday","Monday","Tuesday","Wednesday","Thursday","Friday"
250 DATA 2021,12,25
260 DATA 2022,1,1
270 END
```

### GW-BASIC

```
100 REM Day of the week of Christmas and New Year
110 CLS
120 DIM d$(6)
130 FOR i = 0 TO 6: READ d$(i): NEXT i
140 FOR i = 1 TO 2
150 READ y, m, d
160 PRINT USING "##/##/#### is a "; m; d; y;
170 IF m <= 2 THEN m = m + 12: y = y - 1
180 j = y \ 100
190 k = y MOD 100
200 d = (d + ((m + 1) * 26) \ 10 + k + k \ 4 + j \ 4 + 5 * j) MOD 7
210 PRINT d$(d)
220 NEXT i
230 DATA Saturday, Sunday, Monday, Tuesday, Wednesday, Thursday, Friday
240 DATA 2021, 12, 25
250 DATA 2022, 1, 1
260 END
```

### MSX Basic

The GW-BASIC solution works without any changes.

### QBasic

```
DIM d$(6)
FOR i = 0 TO 6: READ d$(i): NEXT i
FOR i = 1 TO 2
READ y, m, d
PRINT USING "##/##/#### is a "; m; d; y;
IF m <= 2 THEN m = m + 12: y = y - 1
J = y \ 100
K = y MOD 100
d = (d + ((m + 1) * 26) \ 10 + K + K \ 4 + J \ 4 + 5 * J) MOD 7
PRINT d$(d)
NEXT i
DATA Saturday, Sunday, Monday, Tuesday, Wednesday, Thursday, Friday
DATA 2021, 12, 25
DATA 2022, 1, 1
END
```

### True BASIC

```
OPTION BASE 0
DIM d$(6)
FOR i = 0 TO 6
READ d$(i)
NEXT i
FOR i = 1 TO 2
READ y, m, d
PRINT USING "##/##/#### is a ": m, d, y;
IF m <= 2 THEN
LET m = m+12
LET y = y-1
END IF
LET j = IP(round(y)/100)
LET k = REMAINDER(ROUND(y),100)
LET d = REMAINDER(ROUND((d+IP(ROUND(((m+1)*26))/10)+k+IP(ROUND(k)/4)+IP(ROUND(j)/4)+5*j)),7)
PRINT d$(d)
NEXT i
DATA Saturday, Sunday, Monday, Tuesday, Wednesday, Thursday, Friday
DATA 2021, 12, 25
DATA 2022, 1, 1
END
```

### XBasic

```
PROGRAM "progname"
VERSION "0.0000"
DECLARE FUNCTION Entry ()
FUNCTION Entry ()
DIM d$[6]
d$[0] = "Saturday"
d$[1] = "Sunday"
d$[2] = "Monday"
d$[3] = "Tuesday"
d$[4] = "Wednesday"
d$[5] = "Thursday"
d$[6] = "Friday"
y = 2021: m = 12: d = 25
FOR i = 1 TO 2
PRINT d; " /"; m; " /"; y; " is a ";
IF m <= 2 THEN m = m + 12: y = y - 1
J = y \ 100
K = y MOD 100
d = (d + ((m + 1) * 26) \ 10 + K + K \ 4 + J \ 4 + 5 * J) MOD 7
PRINT d$[d]
y = 2022: m = 1: d = 1
NEXT i
END FUNCTION
END PROGRAM
```

### Yabasic

```
dim nombre$(6)
nombre$(0) = "Saturday"
nombre$(1) = "Sunday"
nombre$(2) = "Monday"
nombre$(3) = "Tuesday"
nombre$(4) = "Wednesday"
nombre$(5) = "Thursday"
nombre$(6) = "Friday"
print "Christmas Day 2021 is on a ", diasemana$(2021, 12, 25)
print "New Year's Day 2022 is on a ", diasemana$(2022, 1, 1)
end
sub diasemana$(anno, mes, dia)
if mes <= 2 then
mes = mes + 12
anno = anno - 1
fi
dia = mod((dia-1 + int(((mes+1)*26)/10) + anno + int(anno/4) + int(anno/400) + int(anno*6/100)), 7)
return nombre$(dia)
end sub
```

## BCPL

```
get "libhdr"
let dayofweek(y,m,d) = valof
$( let j, k = ?, ?
if m<=2
$( m := m+12
y := y-1
$)
j := y/100
k := y rem 100
d := (d + ((m+1)*26)/10 + k + k/4 + j/4 + 5*j) rem 7
switchon d into
$( case 0: resultis "Saturday"
case 1: resultis "Sunday"
case 2: resultis "Monday"
case 3: resultis "Tuesday"
case 4: resultis "Wednesday"
case 5: resultis "Thursday"
case 6: resultis "Friday"
$)
$)
let show(y,m,d) be
writef("%N/%N/%N is a %S*N", m, d, y, dayofweek(y, m, d))
let start() be
$( show(2021,12,25)
show(2022,1,1)
$)
```

- Output:

12/25/2021 is a Saturday 1/1/2022 is a Saturday

## C

```
#define _XOPEN_SOURCE
#include <stdio.h>
#include <time.h>
int main() {
struct tm t[2];
strptime("2021-12-25", "%F", &t[0]);
strptime("2022-01-01", "%F", &t[1]);
for (int i=0; i<2; i++) {
char buf[32];
strftime(buf, 32, "%F is a %A", &t[i]);
puts(buf);
}
return 0;
}
```

- Output:

2021-12-25 is a Saturday 2022-01-01 is a Saturday

## CLU

```
day_of_week = proc (d: date) returns (string)
own days: array[string] := array[string]$
[0:"Saturday", "Sunday", "Monday", "Tuesday",
"Wednesday", "Thursday", "Friday"]
m: int := d.month
y: int := d.year
if m <= 2 then
m := m + 12
y := y - 1
end
j: int := y/100
k: int := y//100
dn: int := (d.day + ((m+1)*26)/10 + k + k/4 + j/4 + 5*j)//7
return(days[dn])
end day_of_week
start_up = proc ()
po: stream := stream$primary_output()
days: array[date] := array[date]$
[date$create(25, 12, 2021, 0, 0, 0),
date$create( 1, 1, 2022, 0, 0, 0)]
for d: date in array[date]$elements(days) do
stream$putl(po, date$unparse_date(d) || " is a " || day_of_week(d))
end
end start_up
```

- Output:

25 December 2021 is a Saturday 1 January 2022 is a Saturday

## COBOL

```
IDENTIFICATION DIVISION.
PROGRAM-ID. XMASNY.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 WEEKDAYS.
03 DAY-NAMES.
05 FILLER PIC X(9) VALUE "Saturday ".
05 FILLER PIC X(9) VALUE "Sunday ".
05 FILLER PIC X(9) VALUE "Monday ".
05 FILLER PIC X(9) VALUE "Tuesday ".
05 FILLER PIC X(9) VALUE "Wednesday".
05 FILLER PIC X(9) VALUE "Thursday ".
05 FILLER PIC X(9) VALUE "Friday ".
03 DAYS PIC X(9) OCCURS 7 TIMES,
REDEFINES DAY-NAMES.
01 OUT-FMT.
03 OUT-MONTH PIC 99.
03 FILLER PIC X VALUE "/".
03 OUT-DAY PIC 99.
03 FILLER PIC X VALUE "/".
03 OUT-YEAR PIC 9(4).
03 FILLER PIC X(6) VALUE " is a ".
03 OUT-DAYNAME PIC X(9).
01 VARIABLES.
03 CDATE.
05 D-MONTH PIC 99.
05 D-DAY PIC 99.
05 D-YEAR PIC 9999.
03 ZELLER-DATA.
05 M PIC 99.
05 Y PIC 99.
05 D PIC 999.
05 D7 PIC 999.
05 J PIC 99.
05 K PIC 99.
05 DAY-NAME PIC X(9).
PROCEDURE DIVISION.
BEGIN.
MOVE "25122021" TO CDATE.
PERFORM SHOW-WEEKDAY.
MOVE "01012022" TO CDATE.
PERFORM SHOW-WEEKDAY.
STOP RUN.
SHOW-WEEKDAY.
MOVE D-MONTH TO OUT-MONTH.
MOVE D-DAY TO OUT-DAY.
MOVE D-YEAR TO OUT-YEAR.
PERFORM ZELLER.
MOVE DAY-NAME TO OUT-DAYNAME.
DISPLAY OUT-FMT.
ZELLER.
MOVE D-MONTH TO M.
MOVE D-YEAR TO Y.
IF M IS NOT GREATER THAN 2,
ADD 12 TO M,
SUBTRACT 1 FROM Y.
DIVIDE Y BY 100 GIVING J.
COMPUTE K = Y - J * 100.
COMPUTE D = (M + 1) * 26.
DIVIDE 10 INTO D.
ADD K TO D.
DIVIDE 4 INTO K.
ADD K TO D.
COMPUTE D = D + 5 * J.
DIVIDE 4 INTO J.
COMPUTE D = D + J + D-DAY.
DIVIDE D BY 7 GIVING D7.
MULTIPLY 7 BY D7.
COMPUTE D = D - D7 + 1.
MOVE DAYS(D) TO DAY-NAME.
```

- Output:

25/12/2021 is a Saturday 01/01/2022 is a Saturday

## Cowgol

```
include "cowgol.coh";
record Date is
year: uint16;
month: uint8;
day: uint8;
end record;
sub DayName(date: [Date]): (name: [uint8]) is
var days: [uint8][] := {
"Saturday", "Sunday", "Monday", "Tuesday",
"Wednesday", "Thursday", "Friday"
};
var m := date.month as uint16;
var y := date.year;
var d := date.day as uint16;
if m <= 2 then
m := m + 12;
y := y - 1;
end if;
var j := y / 100;
var k := y % 100;
d := (d + ((m+1)*26)/10 + k + k/4 + j/4 + 5*j) % 7;
name := days[d as @indexof days];
end sub;
sub printDate(date: [Date]) is
print_i8(date.month);
print_char('/');
print_i8(date.day);
print_char('/');
print_i16(date.year);
end sub;
var dates: Date[] := {
{2021, 25, 12},
{2022, 1, 1}
};
var i: @indexof dates := 0;
while i < @sizeof dates loop
printDate(&dates[i]);
print(" is a ");
print(DayName(&dates[i]));
print_nl();
i := i + 1;
end loop;
```

- Output:

25/12/2021 is a Saturday 1/1/2022 is a Saturday

## Delphi

Delphi libraries make this easy.

```
procedure DoChristmasNewYear(Memo: TMemo);
var D: TDate;
begin
D:=EncodeDate(2021,12,25);
Memo.Lines.Add(FormatDateTime('"Christmas Day, 2021 is on: " dddd ', D));
D:=EncodeDate(2022,1,1);
Memo.Lines.Add(FormatDateTime('"New Years Day, 2022 is on: " dddd ', D));
end;
```

- Output:

Christmas Day, 2021 is on: Saturday New Years Day, 2022 is on: Saturday

## Draco

```
type Date = struct {
word year;
byte month, day
};
proc nonrec day_name(Date date) *char:
word m, y, d, j, k;
m := date.month;
y := date.year;
d := date.day;
if m <= 2 then
m := m + 12;
y := y - 1
fi;
j := y / 100;
k := y % 100;
d := (d + ((m+1)*26)/10 + k + (k>>2) + (j>>2) + 5*j) % 7;
case d
incase 0: "Saturday"
incase 1: "Sunday"
incase 2: "Monday"
incase 3: "Tuesday"
incase 4: "Wednesday"
incase 5: "Thursday"
incase 6: "Friday"
esac
corp
proc nonrec print_date(Date d) void:
write(d.month, '/', d.day, '/', d.year)
corp
proc nonrec main() void:
[2] Date dates = ((2021, 12, 25), (2022, 1, 1));
byte i;
for i from 0 upto 1 do
print_date(dates[i]);
writeln(" is a ", day_name(dates[i]))
od
corp
```

- Output:

12/25/2021 is a Saturday 1/1/2022 is a Saturday

## EasyLang

```
func wkday year month day .
adj = (14 - month) div 12
mm = month + 12 * adj - 2
yy = year - adj
r = day + (13 * mm - 1) div 5 + yy + yy div 4 - yy div 100 + yy div 400
return r mod 7 + 1
.
wkdays$[] = [ "Sunday" "Monday" "Tuesday" "Wednesday" "Thursday" "Friday" "Saturday" ]
dates$[] = [ "2021-12-21" "2022-01-01" ]
for d$ in dates$[]
write d$ & " is on "
a[] = number strsplit d$ "-"
print wkdays$[wkday a[1] a[2] a[3]]
.
```

- Output:

2021-12-21 is on Tuesday 2022-01-01 is on Saturday

## F#

```
// Show day of week for Christmas Day, 2021 and New Year's Day, 2022. Nigel Galloway: December 1st., 2021
printfn $"Christmas Day 2021 is a %s{string(System.DateTime(2021,12,25).DayOfWeek)}. New Years Day 2022 is a %s{string(System.DateTime(2022,1,1).DayOfWeek)}."
```

- Output:

Christmas Day 2021 is a Saturday. New Years Day 2022 is a Saturday.

## Factor

```
USING: calendar calendar.english calendar.holidays.us formatting
kernel sequences ;
CONSTANT: msg
"In %d, New Years is on a %s, and Christmas is on a %s.\n"
: day-name ( ts -- str ) day-of-week day-names nth ;
: christmas ( n -- str ) christmas-day day-name ;
: new-years ( n -- str ) new-years-day day-name ;
: holidays ( n -- ny ch ) [ new-years ] [ christmas ] bi ;
: .holidays ( seq -- ) [ dup holidays msg printf ] each ;
{ 1578 1590 1642 1957 2020 2021 2022 2242 2245 2393 } .holidays
```

- Output:

In 1578, New Years is on a Sunday, and Christmas is on a Monday. In 1590, New Years is on a Monday, and Christmas is on a Tuesday. In 1642, New Years is on a Wednesday, and Christmas is on a Thursday. In 1957, New Years is on a Tuesday, and Christmas is on a Wednesday. In 2020, New Years is on a Wednesday, and Christmas is on a Friday. In 2021, New Years is on a Friday, and Christmas is on a Saturday. In 2022, New Years is on a Saturday, and Christmas is on a Sunday. In 2242, New Years is on a Saturday, and Christmas is on a Sunday. In 2245, New Years is on a Wednesday, and Christmas is on a Thursday. In 2393, New Years is on a Friday, and Christmas is on a Saturday.

## FreeBASIC

```
#include "vbcompat.bi" 'contains functions for dealing with dates and times
#include "string.bi" 'contains functions for formatting text strings
dim as double christmas = DateSerial(2021, 12, 25) 'enter the dates of the two holidays
dim as double newyears = DateSerial(2022, 01, 01)
print "Christmas Day 2021 is on a "; format(christmas,"dddd")
print "New Year's Day 2022 is on a "; format(newyears, "dddd")
```

- Output:

Christmas Day 2021 is on a Saturday New Year's Day 2022 is on a Saturday

## J

```
(weekday 2021 12 25){::;:'Sun Mon Tue Wed Thu Fri Sat'
Sat
(weekday 2022 01 01){::;:'Sun Mon Tue Wed Thu Fri Sat'
Sat
```

## jq

**Works with gojq, the Go implementation of jq**

Years, output format, and output are exactly as for Wren.

```
def weekdaynames:
["Sunday", "Monday","Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"];
# example: weekday(1999; 12; 25)
def weekday($year; $month; $day):
"\($year)-\($month)-\($day)" | strptime("%Y-%m-%d") | weekdaynames[.[-2]];
1578, 1590, 1642, 1957, 2020, 2021, 2022, 2242, 2245, 2393
| "In \(.), New year's day is on a \(weekday(.;1;1)), and Christmas day on \(weekday(.;12;25))."
```

- Output:

As for #Wren

## Julia

See also https://docs.julialang.org/en/v1/stdlib/Dates/#Dates.format-Tuple{TimeType,%20AbstractString}

```
using Dates
for year in [1578, 1590, 1642, 1957, 2020, 2021, 2022, 2242, 2245, 2393]
println("Year $year, New Years's Day: ", Dates.format(DateTime(year, 1, 1), "E, U d, Y"),
" and Christmas: ", Dates.format(DateTime(year, 12, 25), "E, U d, Y"))
end
```

- Output:

Year 1578, New Years's Day: Sunday, January 1, 1578 and Christmas: Monday, December 25, 1578 Year 1590, New Years's Day: Monday, January 1, 1590 and Christmas: Tuesday, December 25, 1590 Year 1642, New Years's Day: Wednesday, January 1, 1642 and Christmas: Thursday, December 25, 1642 Year 1957, New Years's Day: Tuesday, January 1, 1957 and Christmas: Wednesday, December 25, 1957 Year 2020, New Years's Day: Wednesday, January 1, 2020 and Christmas: Friday, December 25, 2020 Year 2021, New Years's Day: Friday, January 1, 2021 and Christmas: Saturday, December 25, 2021 Year 2022, New Years's Day: Saturday, January 1, 2022 and Christmas: Sunday, December 25, 2022 Year 2242, New Years's Day: Saturday, January 1, 2242 and Christmas: Sunday, December 25, 2242 Year 2245, New Years's Day: Wednesday, January 1, 2245 and Christmas: Thursday, December 25, 2245 Year 2393, New Years's Day: Friday, January 1, 2393 and Christmas: Saturday, December 25, 2393

## Nim

```
import std/times
echo "25th of December 2021 is a ", getDayOfWeek(25, mDec, 2021)
echo "1st of January 2022 is a ", getDayOfWeek(1, mJan, 2022)
```

- Output:

25th of December 2021 is a Saturday 1st of January 2022 is a Saturday

## Nu

`[2021-12-25 2022-01-01] | each { format date "%F \u{25b6} %A\n" } | str join`

- Output:

2021-12-25 ▶ Saturday 2022-01-01 ▶ Saturday

## Oberon-07

Using the minimal Dates module from the Find the last Sunday of_each month#Oberon-07 sample (code not repeated here), we can solve the task:

```
MODULE ChristmasAndNewYear;
IMPORT Dates, Out;
PROCEDURE OutDayName ( day : INTEGER ) ;
BEGIN
IF day = Dates.SUNDAY THEN Out.String( "Sunday" )
ELSIF day = Dates.MONDAY THEN Out.String( "Monday" )
ELSIF day = Dates.TUESDAY THEN Out.String( "Tuesday" )
ELSIF day = Dates.WEDNESDAY THEN Out.String( "Wednesday" )
ELSIF day = Dates.THURSDAY THEN Out.String( "Thursday" )
ELSIF day = Dates.FRIDAY THEN Out.String( "Friday" )
ELSIF day = Dates.SATURDAY THEN Out.String( "Saturday" )
ELSE Out.String( "Invaliday" )
END
END OutDayName ;
BEGIN
Out.String( "25th of December 2024 is a " ); OutDayName( Dates.dayOfWeek( 25, 12, 2024 ) );
Out.Ln;
Out.String( " 1st of January 2025 is a " ); OutDayName( Dates.dayOfWeek( 1, 1, 2025 ) )
END ChristmasAndNewYear.
```

- Output:

25th of December 2024 is a Wednesday 1st of January 2025 is a Wednesday

## ooRexx

```
/* REXX */
Call wkd 2021,12,25
Call wkd 2022,01,01
Exit
wkd:
Parse Arg y,m,d
wd=.Array~of('Monday','Tuesday','Wednesday','Thursday','Friday','Saturday','Sunday')
dt=.DateTime~new(y,m,d)
say d'.'m'.'y 'is a' wd[dt~weekday]
Return
```

- Output:

25.12.2021 is a Saturday 01.01.2022 is a Saturday<

## Pascal

### Free Pascal

```
Program daysofweek;
Uses sysutils;
Const Years : array Of integer = (1578, 1590, 1642, 1957, 2020, 2021, 2022, 2242, 2245, 2393);
Var christmasday, newyearsday : tdatetime;
year : integer;
Begin
For year In years Do
Begin
christmasday := encodeDate(year,12,25);
newyearsday := encodeDate(year,1,1);
writeln('in ',year,' New Years day is on ',DefaultFormatSettings.LongDayNames[DayOfWeek(
newyearsday)],', and Christmas day on a ',DefaultFormatSettings.LongDayNames[DayOfWeek(
christmasday
)]);
End;
End.
```

- Output:

in 1578 New Years day is on Sunday, and Christmas day on a Monday in 1590 New Years day is on Monday, and Christmas day on a Tuesday in 1642 New Years day is on Wednesday, and Christmas day on a Thursday in 1957 New Years day is on Tuesday, and Christmas day on a Wednesday in 2020 New Years day is on Wednesday, and Christmas day on a Friday in 2021 New Years day is on Friday, and Christmas day on a Saturday in 2022 New Years day is on Saturday, and Christmas day on a Sunday in 2242 New Years day is on Saturday, and Christmas day on a Sunday in 2245 New Years day is on Wednesday, and Christmas day on a Thursday in 2393 New Years day is on Friday, and Christmas day on a Saturday

## Perl

```
#!/usr/bin/perl
use strict; # https://rosettacode.org/wiki/What_weekdays_will_Christmas_and_New_Year
use warnings;
use Time::Local;
for (
['Christmas 2021', 25, 11, 2021 ],
['New Years 2022', 1, 0, 2022 ],
)
{
print "$_->[0] ", qw( Sunday Monday Tuesday Wednesday Thursday Fridat Saturday )
[(localtime timelocal(0, 0, 12, @{$_}[1..3]))[6]], "\n";
}
```

- Output:

Christmas 2021 Saturday New Years 2022 Saturday

## Phix

with javascript_semantics include timedate.e procedure nyc(integer year) string ny = format_timedate({year,1,1,0,0,0},"Dddd"), cd = format_timedate({year,12,25,0,0,0},"Dddd") printf(1,"In %d, New year's day is on a %s, and Christmas day on a %s.\n",{year,ny,cd}) end procedure papply({1578, 1590, 1642, 1957, 2020, 2021, 2022, 2242, 2245, 2393},nyc)

Note the builtin timedate type does not officially support dates prior to *1752*... the fact that the first three lines agree with other entries on this page is pure luck.

- Output:

In 1578, New year's day is on a Sunday, and Christmas day on a Monday. In 1590, New year's day is on a Monday, and Christmas day on a Tuesday. In 1642, New year's day is on a Wednesday, and Christmas day on a Thursday. In 1957, New year's day is on a Tuesday, and Christmas day on a Wednesday. In 2020, New year's day is on a Wednesday, and Christmas day on a Friday. In 2021, New year's day is on a Friday, and Christmas day on a Saturday. In 2022, New year's day is on a Saturday, and Christmas day on a Sunday. In 2242, New year's day is on a Saturday, and Christmas day on a Sunday. In 2245, New year's day is on a Wednesday, and Christmas day on a Thursday. In 2393, New year's day is on a Friday, and Christmas day on a Saturday.

## PL/I

```
xmas_and_newyear: procedure options(main);
day_name: procedure(year,month,day) returns(char(9) varying);
declare days(0:6) char(9) varying;
declare (year, month, day) fixed;
declare (y, m, d, j, k) fixed;
days(0) = 'Saturday';
days(1) = 'Sunday';
days(2) = 'Monday';
days(3) = 'Tuesday';
days(4) = 'Wednesday';
days(5) = 'Thursday';
days(6) = 'Friday';
m = month;
y = year;
if m <= 2 then do;
m = m + 12;
y = y -1;
end;
j = y/100;
k = mod(y,100);
d = mod((day + ((m+1)*26)/10 + k + k/4 + j/4 + 5*j),7);
return(days(d));
end day_name;
declare years(2) fixed static initial(2021, 2022);
declare months(2) fixed static initial( 12, 1);
declare days(2) fixed static initial( 25, 1);
declare i fixed;
do i=1 to 2;
put skip edit(months(i),'/',days(i),'/',years(i),
' is a ',
day_name(years(i),months(i),days(i)))
(F(2),A,F(2),A,F(4),A,A);
end;
end xmas_and_newyear;
```

- Output:

12/25/2021 is a Saturday 1/ 1/2022 is a Saturday

## PL/M

```
100H:
BDOS: PROCEDURE(F,A); DECLARE F BYTE, A ADDRESS; GO TO 5; END BDOS;
EXIT: PROCEDURE; GO TO 0; END EXIT;
PR$CH: PROCEDURE(C); DECLARE C BYTE; CALL BDOS(2,C); END PR$CH;
PR$STR: PROCEDURE(S); DECLARE S ADDRESS; CALL BDOS(9,S); END PR$STR;
PR$NUM: PROCEDURE(N);
DECLARE S(6) BYTE INITIAL ('.....$');
DECLARE (N, P) ADDRESS, D BASED P BYTE;
P = .S(5);
DIGIT:
P = P-1;
D = '0' + N MOD 10;
IF (N := N/10) > 0 THEN GO TO DIGIT;
CALL PR$STR(P);
END PR$NUM;
DAY$NAME: PROCEDURE(Y,M,D) ADDRESS;
DECLARE (Y,M,D,J,K) ADDRESS;
IF M <= 2 THEN DO;
M = M + 12;
Y = Y - 1;
END;
J = Y / 100;
K = Y MOD 100;
D = (D + ((M+1)*26)/10 + K + SHR(K,2) + SHR(J,2) + 5*6) MOD 7;
DO CASE D;
RETURN .'SATURDAY$';
RETURN .'SUNDAY$';
RETURN .'MONDAY$';
RETURN .'TUESDAY$';
RETURN .'WEDNESDAY$';
RETURN .'THURSDAY$';
RETURN .'FRIDAY$';
END;
END DAY$NAME;
PR$DATE: PROCEDURE(Y,M,D);
DECLARE Y ADDRESS, (M, D) BYTE;
CALL PR$NUM(M);
CALL PR$CH('/');
CALL PR$NUM(D);
CALL PR$CH('/');
CALL PR$NUM(Y);
END PR$DATE;
DECLARE YEARS(2) ADDRESS INITIAL (2021, 2022);
DECLARE MONTHS(2) BYTE INITIAL ( 12, 1);
DECLARE DAYS(2) BYTE INITIAL ( 25, 1);
DECLARE I BYTE;
DO I=0 TO 1;
CALL PR$DATE(YEARS(I),MONTHS(I),DAYS(I));
CALL PR$STR(.' IS A $');
CALL PR$STR(DAY$NAME(YEARS(I),MONTHS(I),DAYS(I)));
CALL PR$STR(.(13,10,'$'));
END;
CALL EXIT;
EOF
```

- Output:

12/25/2021 IS A SATURDAY 1/1/2022 IS A SATURDAY

## Python

```
import datetime
weekDays = ("Monday","Tuesday","Wednesday","Thursday","Friday","Saturday","Sunday")
thisXMas = datetime.date(2021,12,25)
thisXMasDay = thisXMas.weekday()
thisXMasDayAsString = weekDays[thisXMasDay]
print("This year's Christmas is on a {}".format(thisXMasDayAsString))
nextNewYear = datetime.date(2022,1,1)
nextNewYearDay = nextNewYear.weekday()
nextNewYearDayAsString = weekDays[nextNewYearDay]
print("Next new year is on a {}".format(nextNewYearDayAsString))
```

- Output:

This year's Christmas is on a Saturday Next new year is on a Saturday

## Quackery

`dayofweek`

is defined at Day of the week#Quackery.

```
[ [ table
$ "Sun" $ "Mon"
$ "Tues" $ "Wednes"
$ "Thurs" $ "Fri"
$ "Satur" ]
do $ "day" join ] is day ( n --> $ )
[ 25 12 rot dayofweek ] is christmas ( n --> $ )
[ 1 1 rot dayofweek ] is newyear's ( n --> $ )
2021 christmas day echo$ cr
2022 newyear's day echo$ cr
```

- Output:

Saturday Saturday

## Raku

```
my @d-o-w = < Sunday Monday Tuesday Wednesday Thursday Friday Saturday >;
.say for (flat 2020..2022, (1500 .. 2500).roll(7)).sort.map: {
"In {$_}, New Years is on a { @d-o-w[Date.new($_, 1, 1).day-of-week % 7] }, " ~
"and Christmas on a { @d-o-w[Date.new($_, 12, 25).day-of-week % 7] }."
}
```

- Sample output:

In 1578, New Years is on a Sunday, and Christmas on a Monday. In 1590, New Years is on a Monday, and Christmas on a Tuesday. In 1642, New Years is on a Wednesday, and Christmas on a Thursday. In 1957, New Years is on a Tuesday, and Christmas on a Wednesday. In 2020, New Years is on a Wednesday, and Christmas on a Friday. In 2021, New Years is on a Friday, and Christmas on a Saturday. In 2022, New Years is on a Saturday, and Christmas on a Sunday. In 2242, New Years is on a Saturday, and Christmas on a Sunday. In 2245, New Years is on a Wednesday, and Christmas on a Thursday. In 2393, New Years is on a Friday, and Christmas on a Saturday.

## Ring

```
? "working..."
weekdays = ["Mon","Tues","Wednes","Thurs","Fri","Satur","Sun"]
dow = timelist()[15]
today = date()
tycd = "25/12/" + substr(today, 7, 4)
nnyd = "01/01/" + string(number(substr(today, 7, 4)) + 1)
for day = 0 to 366
anotherday = adddays(today, day)
if anotherday = tycd
? "This year's Christmas day is on a " + nameof(day) + "."
ok
if anotherday = nnyd
? "The next New Year's day is on a " + nameof(day) + "."
exit
ok
next
put "done..."
func nameof day
return weekdays[((day + today - 1) % 7) + 1] + "day"
```

- Output:

working... This year's Christmas day is on a Saturday. The next New Year's day is on a Saturday. done...

## RPL

```
≪ 1000000 / 25.12 + 0
TSTR 1 3 SUB
"X-MAS: " OVER +
"NEW YEAR: " ROT +
≫ 'TASK' STO
```

```
2021 TASK
```

- Output:

2: "X-MAS: SAT" 1: "NEW YEAR: SAT"

## Ruby

This uses the same years as the Raku example. The Ruby Date class does however take the calendar reform (default 1582) into account, so the days for 1578 differ from all other languages so far.

```
require 'date'
years = [1578, 1590, 1642, 1957, 2020, 2021, 2022, 2242, 2245, 2393]
years.each do |year|
xmas = Date.new(year,12,25).strftime("%A")
ny = Date.new(year, 1, 1).strftime("%A")
puts "In #{year}, New year's day is on a #{ny}, and Christmas day on #{xmas}."
end
```

- Output:

In 1578, New year's day is on a Wednesday, and Christmas day on Thursday. In 1590, New year's day is on a Monday, and Christmas day on Tuesday. In 1642, New year's day is on a Wednesday, and Christmas day on Thursday. In 1957, New year's day is on a Tuesday, and Christmas day on Wednesday. In 2020, New year's day is on a Wednesday, and Christmas day on Friday. In 2021, New year's day is on a Friday, and Christmas day on Saturday. In 2022, New year's day is on a Saturday, and Christmas day on Sunday. In 2242, New year's day is on a Saturday, and Christmas day on Sunday. In 2245, New year's day is on a Wednesday, and Christmas day on Thursday. In 2393, New year's day is on a Friday, and Christmas day on Saturday.

## Wren

This uses the same years as the Raku example.

The above module uses the Gregorian Proleptic calendar and therefore gives the wrong days of the week for 1578 as the earliest year for the adoption of the Gregorian calendar was 1582 when 10 days (from 5th until 14th October inclusive) were omitted. To get the correct days for 1578 (and agree with the Ruby entry) we therefore need to add 10 days to the Gregorian date which the *Date.fromJulian* method does automatically.

```
import "./date" for Date
System.print("Days of week per Gregorian Proleptic calendar:")
var years = [1578, 1590, 1642, 1957, 2020, 2021, 2022, 2242, 2245, 2393]
for (year in years) {
var newYear = Date.new(year, 1, 1).weekDay
var xmas = Date.new(year, 12, 25).weekDay
System.print(" In %(year), New year's day is on a %(newYear), and Christmas day on %(xmas).")
}
System.print("\nActual days for 1578 (Julian calendar) were 10 days later:")
System.print(" New Year's day was on %(Date.fromJulian(1578, 1, 1).weekDay), and Christmas day on %(Date.fromJulian(1578, 12, 25).weekDay).")
```

- Output:

Days of week per Gregorian Proleptic calendar: In 1578, New year's day is on a Sunday, and Christmas day on Monday. In 1590, New year's day is on a Monday, and Christmas day on Tuesday. In 1642, New year's day is on a Wednesday, and Christmas day on Thursday. In 1957, New year's day is on a Tuesday, and Christmas day on Wednesday. In 2020, New year's day is on a Wednesday, and Christmas day on Friday. In 2021, New year's day is on a Friday, and Christmas day on Saturday. In 2022, New year's day is on a Saturday, and Christmas day on Sunday. In 2242, New year's day is on a Saturday, and Christmas day on Sunday. In 2245, New year's day is on a Wednesday, and Christmas day on Thursday. In 2393, New year's day is on a Friday, and Christmas day on Saturday. Actual days for 1578 (Julian calendar) were 10 days later: New Year's day was on Wednesday, and Christmas day on Thursday.

## XPL0

```
func WeekDay(Year, Month, Day); \Return address of day of week
int Year, Month, Day; \Works for years 1583 onward
int DayOfWeek, Names;
[if Month<=2 then [Month:= Month+12; Year:= Year-1];
DayOfWeek:= rem((Day-1 + (Month+1)*26/10 + Year + Year/4 + Year/100*6 + Year/400)/7);
Names:= ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"];
return Names(DayOfWeek);
]; \WeekDay
[Text(0, "This Christmas is on a ");
Text(0, WeekDay(2021, 12, 25)); CrLf(0);
Text(0, "This New Year's Day is on a ");
Text(0, WeekDay(2022, 1, 1)); CrLf(0);
]
```

- Output:

This Christmas is on a Saturday This New Year's Day is on a Saturday