Calendar

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Task
Calendar
You are encouraged to solve this task according to the task description, using any language you may know.

Create a routine that will generate a text calendar for any year. Test the calendar by generating a calendar for the year 1969, on a device of the time. Choose one of the following devices:

  • A line printer with a width of 132 characters.
  • An IBM 3278 model 4 terminal (80×43 display with accented characters). Target formatting the months of the year to fit nicely across the 80 character width screen. Restrict number of lines in test output to 43.

(Ideally, the program will generate well-formatted calendars for any page width from 20 characters up.)

Kudos (κῦδος) for routines that also correctly transition from Julian to Gregorian calendar in September 1752.

This task is inspired by Real Programmers Don't Use PASCAL by Ed Post, Datamation, volume 29 number 7, July 1983.

THE REAL PROGRAMMER'S NATURAL HABITAT
"Taped to the wall is a line-printer Snoopy calender for the year 1969."

For further Kudos see task CALENDAR, where all code is to be in UPPERCASE.

For economy of size, do not actually include Snoopy generation in either the code or the output, instead just output a place-holder.

Ada

Specification of a "Printable_Calendar" package (printable_calendar.ads):

<lang Ada>with Ada.Calendar.Formatting;

package Printable_Calendar is

  subtype String20 is String(1 .. 20);
  type Month_Rep_Type is array (Ada.Calendar.Month_Number) of String20;
  type Description is record
     Weekday_Rep: String20;
     Month_Rep: Month_Rep_Type;
  end record;
  -- for internationalization, you only need to define a new description
  Default_Description: constant Description :=
    (Weekday_Rep =>
      "Mo Tu We Th Fr Sa So",
     Month_Rep   =>
     ("      January       ", "      February      ", "       March        ",
      "       April        ", "        May         ", "        June        ",
      "        July        ", "       August       ", "      September     ",
      "       October      ", "      November      ", "      December      "));
  type Calendar (<>) is tagged private;
  -- Initialize a calendar for devices with 80- or 132-characters per row
  function Init_80(Des: Description := Default_Description) return Calendar;
  function Init_132(Des: Description := Default_Description) return Calendar;
  -- the following procedures output to standard IO; override if neccessary
  procedure New_Line(Cal: Calendar);
  procedure Put_String(Cal: Calendar; S: String);
  -- the following procedures do the real stuff
  procedure Print_Line_Centered(Cal: Calendar'Class; Line: String);
  procedure Print(Cal: Calendar'Class;
                  Year:  Ada.Calendar.Year_Number;
                  Year_String: String); -- this is the main Thing

private

     type Calendar is tagged record
     Columns, Rows, Space_Between_Columns: Positive;
     Left_Space: Natural;
     Weekday_Rep: String20;
     Month_Rep: Month_Rep_Type;
  end record;

end Printable_Calendar;</lang>

Next the implementation (printable_calendar.ads):

<lang Ada>with Ada.Text_IO;

package body Printable_Calendar is

  use Ada.Calendar;
  package F renames Ada.Calendar.Formatting;
  function Days_Per_Month(Year: Year_Number; Month: Month_Number)
                         return Day_Number is
  begin
     case Month is
        when 1 | 3 | 5 | 7 | 8 | 10 | 12 => return 31;
        when 4 | 6 | 9 | 11              => return 30;
        when 2 =>
           if Year mod 4 /= 0 then
              return 28;
           elsif Year mod 100 /= 0 then
              return 29;
           elsif Year mod 400 /= 0 then
              return 28;
           else
              return 29;
           end if;
     end case;
  end Days_Per_Month;
  type Full_Month_Rep is array (1 .. 6) of String20;
  function Generate_Printable_Month (Y: Ada.Calendar.Year_Number;
                                     M: Ada.Calendar.Month_Number)
                                    return Full_Month_Rep is
     X: Full_Month_Rep := (others => "                    ");
     -- If X=Generate_Printable_Month(2011, 01), the result could be
     --  "       January      ", -- Month_Rep(01)
     --  "Mo Tu We Th Fr Sa Su"  -- Weekday_Rep
     --  "                1  2"  -- X(1)
     --  " 3  4  5  6  7  8  9"  -- X(2)
     --  "10 11 12 13 14 15 16"  -- X(3)
     --  "17 18 19 20 21 22 23"  -- X(4)
     --  "24 25 26 27 28 29 30"  -- X(5)
     --  "31                  "  -- X(6)
     Row:       Integer range 1 .. 6  := 1;
     Day_Index: constant array(F.Day_Name) of Positive
       := (1, 4, 7, 10, 13, 16, 19);
  begin
     for I in 1 .. Days_Per_Month(Y, M) loop
        declare
          Weekday: constant F.Day_Name    := F.Day_Of_Week(F.Time_Of(Y, M, I));
          Pos: constant Positive          := Day_Index(Weekday);
          Cleartext_Name: constant String := Day_Number'Image(I);
          L: constant Positive            := Cleartext_Name'Last;
        begin
           X(Row)(Pos .. Pos+1) := Cleartext_Name(L-1 .. L);
           if F."="(Weekday, F.Sunday) then
              Row := Row + 1;
           end if;
        end;
     end loop;
     return X;
  end Generate_Printable_Month;


  procedure Print(Cal: Calendar'class;
                  Year:  Ada.Calendar.Year_Number;
                  Year_String: String) is
     The_Month: Month_Number := Month_Number'First;
     procedure Write_Space(Length: Natural) is
     begin
        for I in 1 .. Length loop
           Cal.Put_String(" ");
        end loop;
     end Write_Space;
     Year_Rep: array(Month_Number) of Full_Month_Rep;
  begin
     -- print the year
     Cal.Print_Line_Centered(Year_String);
     -- generate a printable form for all the months
     for Month in Month_Number loop
        Year_Rep(Month) := Generate_Printable_Month(Year, Month);
     end loop;
     begin
        while True loop
           -- new line
           Cal.New_Line;
           -- write month names
           Write_Space(Cal.Left_Space);
           for Month in The_Month .. The_Month+Cal.Columns-2 loop
              Cal.Put_String(Cal.Month_Rep(Month));
              Write_Space(Cal.Space_Between_Columns);
           end loop;
           Cal.Put_String(Cal.Month_Rep(The_Month+Cal.Columns-1));
           Cal.New_Line;
           -- write "Mo Tu .. So" - or whatever is defined by Weekday_Rep
           Write_Space(Cal.Left_Space);
           for Month in The_Month .. The_Month+Cal.Columns-2 loop
              Cal.Put_String(Cal.Weekday_Rep);
              Write_Space(Cal.Space_Between_Columns);
           end loop;
           Cal.Put_String(Cal.Weekday_Rep);
           Cal.New_Line;
           -- write the dates
           for I in 1 .. 6 loop
              Write_Space(Cal.Left_Space);
              for Month in The_Month .. The_Month+Cal.Columns-2 loop
                 Cal.Put_String(Year_Rep(Month)(I));
                 Write_Space(Cal.Space_Between_Columns);
              end loop;
           Cal.Put_String(Year_Rep(The_Month+Cal.Columns-1)(I));
           Cal.New_Line;
           end loop;
           The_Month := The_Month + Cal.Columns;
           -- this will eventually raise Constraint_Error to terminate the loop
        end loop;
     exception
        when Constraint_Error => null;
     end;
  end Print;
  procedure New_Line(Cal: Calendar) is
  begin
     Ada.Text_IO.New_Line;
  end New_Line;
  procedure Put_String(Cal: Calendar; S: String) is
  begin
     Ada.Text_IO.Put(S);
  end Put_String;
  procedure Print_Line_Centered(Cal: Calendar'Class; Line: String) is
     Width : constant Positive := Cal.Columns*20
       + (Cal.Columns-1)*Cal.Space_Between_Columns
       + Cal.Left_Space;
  begin
     if Line'Length    >= Width-1 then
        Cal.Put_String(Line);
        Cal.New_Line;
     else
        Print_Line_Centered(Cal, " " & Line & " ");
     end if;
  end Print_Line_Centered;
  function Init_80(Des: Description := Default_Description) return Calendar is
     X: Calendar:=
       (Columns => 3, Rows => 4, Space_Between_Columns => 4,
        Left_Space => 1,
        Weekday_Rep =>  Des.Weekday_Rep,
        Month_Rep   =>  Des.Month_Rep
       );
  begin
     return X;
  end Init_80;
  function Init_132(Des: Description := Default_Description) return Calendar is
     X: Calendar:=
       (Columns => 6, Rows => 2, Space_Between_Columns => 2,
        Left_Space => 1,
        Weekday_Rep =>  Des.Weekday_Rep,
        Month_Rep   =>  Des.Month_Rep
       );
  begin
     return X;
  end Init_132;

end Printable_Calendar;</lang>

Now, the main program is really simple:

<lang Ada>with Printable_Calendar;

procedure Cal is

  C: Printable_Calendar.Calendar := Printable_Calendar.Init_80;

begin

  C.Print_Line_Centered("[reserved for Snoopy]");
  C.New_Line;
  C.Print(1969, "Nineteen-Sixty-Nine");

end Cal;</lang>

Here is the output:

                        [reserved for Snoopy]                        

                         Nineteen-Sixty-Nine                         

       January                 February                 March        
 Mo Tu We Th Fr Sa So    Mo Tu We Th Fr Sa So    Mo Tu We Th Fr Sa So
        1  2  3  4  5                    1  2                    1  2
  6  7  8  9 10 11 12     3  4  5  6  7  8  9     3  4  5  6  7  8  9
 13 14 15 16 17 18 19    10 11 12 13 14 15 16    10 11 12 13 14 15 16
 20 21 22 23 24 25 26    17 18 19 20 21 22 23    17 18 19 20 21 22 23
 27 28 29 30 31          24 25 26 27 28          24 25 26 27 28 29 30
                                                 31                  

        April                    May                     June        
 Mo Tu We Th Fr Sa So    Mo Tu We Th Fr Sa So    Mo Tu We Th Fr Sa So
     1  2  3  4  5  6              1  2  3  4                       1
  7  8  9 10 11 12 13     5  6  7  8  9 10 11     2  3  4  5  6  7  8
 14 15 16 17 18 19 20    12 13 14 15 16 17 18     9 10 11 12 13 14 15
 21 22 23 24 25 26 27    19 20 21 22 23 24 25    16 17 18 19 20 21 22
 28 29 30                26 27 28 29 30 31       23 24 25 26 27 28 29
                                                 30                  

         July                   August                 September     
 Mo Tu We Th Fr Sa So    Mo Tu We Th Fr Sa So    Mo Tu We Th Fr Sa So
     1  2  3  4  5  6                 1  2  3     1  2  3  4  5  6  7
  7  8  9 10 11 12 13     4  5  6  7  8  9 10     8  9 10 11 12 13 14
 14 15 16 17 18 19 20    11 12 13 14 15 16 17    15 16 17 18 19 20 21
 21 22 23 24 25 26 27    18 19 20 21 22 23 24    22 23 24 25 26 27 28
 28 29 30 31             25 26 27 28 29 30 31    29 30               
                                                                     

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


To get a 132-character-wide output, you just have to replace "Init_80" by "Init_132" in the main program.

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.

<lang algol68>#!/usr/local/bin/a68g --script #

PROC print calendar = (INT year, page width)VOID: (

 []STRING month names = (
     "January","February","March","April","May","June",
     "July","August","September","October","November","December"),
   weekday names = ("Su","Mo","Tu","We","Th","Fr","Sa");
 FORMAT weekday fmt = $g,n(UPB weekday names - LWB weekday names)(" "g)$;
 # Juggle the calendar format to fit the printer/screen width #
 INT day width = UPB weekday names[1], day gap=1;
 INT month width = (day width+day gap) * UPB weekday names-1;
 INT month heading lines = 2;
 INT month lines = (31 OVER UPB weekday names+month heading lines+2); # +2 for head/tail weeks #
 INT year cols = (page width+1) OVER (month width+1);
 INT year rows = (UPB month names-1)OVER year cols + 1;
 INT month gap = (page width - year cols*month width + 1)OVER year cols;
 INT year width = year cols*(month width+month gap)-month gap;
 INT year lines = year rows*month lines;
 MODE MONTHBOX = [month lines, month width]CHAR;
 MODE YEARBOX  = [year  lines, year  width]CHAR;
 INT week start = 1; # Sunday #
 PROC days in month = (INT year, month)INT:
   CASE month IN 31,
     IF year MOD 4 EQ 0 AND year MOD 100 NE 0 OR year MOD 400 EQ 0 THEN 29 ELSE 28 FI,
     31, 30, 31, 30, 31, 31, 30, 31, 30, 31
   ESAC;
 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
 );
 MODE SIMPLEOUT = UNION(STRING, []STRING, INT);
 PROC cputf = (REF[]CHAR out, FORMAT fmt, SIMPLEOUT argv)VOID:(
   FILE f; STRING s; associate(f,s);
   putf(f, (fmt, argv));
   out[:UPB s]:=s;
   close(f)
 );
 PROC month repr = (INT year, month)MONTHBOX:(
   MONTHBOX month box; FOR line TO UPB month box DO month box[line,]:=" "* 2 UPB month box OD;
   STRING month name = month names[month];
 # center the title #
   cputf(month box[1,(month width - UPB month name ) OVER 2+1:], $g$, month name);
   cputf(month box[2,], weekday fmt, weekday names);
   INT first day := day of week(year, month, 1);
   FOR day TO days in month(year, month) DO
     INT line = (day+first day-week start) OVER UPB weekday names + month heading lines + 1;
     INT char =((day+first day-week start) MOD UPB weekday names)*(day width+day gap) + 1;
     cputf(month box[line,char:char+day width-1],$g(-day width)$, day)
   OD;
   month box
 );
 PROC year repr = (INT year)YEARBOX:(
   YEARBOX year box;
   FOR line TO UPB year box DO year box[line,]:=" "* 2 UPB year box OD;
   FOR month row FROM 0 TO year rows-1 DO
     FOR month col FROM 0 TO year cols-1 DO
       INT month = month row * year cols + month col + 1;
       IF month > UPB month names THEN
         done
       ELSE
         INT month col width = month width+month gap;
         year box[
           month row*month lines+1 : (month row+1)*month lines,
           month col*month col width+1 : (month col+1)*month col width-month gap
         ] := month repr(year, month)
       FI
     OD
   OD;
   done: year box
 );
 INT center = (year cols*(month width+month gap) - month gap - 1) OVER 2;
 INT indent = (page width - year width) OVER 2;
 printf((
   $n(indent + center - 9)k  g l$, "[Insert Snoopy here]",
   $n(indent + center - 1)k 4d l$, year, $l$,
   $n(indent)k n(year width)(g)  l$, year repr(year)
 ))

);

main: ( CO inspired by http://www.ee.ryerson.ca/~elf/hack/realmen.html

          Real Programmers Don't Use PASCAL - Ed Post
           Datamation, volume 29 number 7, July 1983
             THE REAL PROGRAMMER'S NATURAL HABITAT

"Taped to the wall is a line-printer Snoopy calender for the year 1969." CO

 INT mankind stepped on the moon = 1969,
     line printer width = 80; # as at 1969! #
 print calendar(mankind stepped on the moon, line printer width)

)</lang> Output:

                             [Insert Snoopy here]
                                     1969

        January                    February                    March        
  Su Mo Tu We Th Fr Sa       Su Mo Tu We Th Fr Sa       Su Mo Tu We Th Fr Sa
            1  2  3  4                          1                          1
   5  6  7  8  9 10 11        2  3  4  5  6  7  8        2  3  4  5  6  7  8
  12 13 14 15 16 17 18        9 10 11 12 13 14 15        9 10 11 12 13 14 15
  19 20 21 22 23 24 25       16 17 18 19 20 21 22       16 17 18 19 20 21 22
  26 27 28 29 30 31          23 24 25 26 27 28          23 24 25 26 27 28 29
                                                        30 31               
         April                       May                        June        
  Su Mo Tu We Th Fr Sa       Su Mo Tu We Th Fr Sa       Su Mo Tu We Th Fr Sa
         1  2  3  4  5                    1  2  3        1  2  3  4  5  6  7
   6  7  8  9 10 11 12        4  5  6  7  8  9 10        8  9 10 11 12 13 14
  13 14 15 16 17 18 19       11 12 13 14 15 16 17       15 16 17 18 19 20 21
  20 21 22 23 24 25 26       18 19 20 21 22 23 24       22 23 24 25 26 27 28
  27 28 29 30                25 26 27 28 29 30 31       29 30               
                                                                            
          July                      August                   September      
  Su Mo Tu We Th Fr Sa       Su Mo Tu We Th Fr Sa       Su Mo Tu We Th Fr Sa
         1  2  3  4  5                       1  2           1  2  3  4  5  6
   6  7  8  9 10 11 12        3  4  5  6  7  8  9        7  8  9 10 11 12 13
  13 14 15 16 17 18 19       10 11 12 13 14 15 16       14 15 16 17 18 19 20
  20 21 22 23 24 25 26       17 18 19 20 21 22 23       21 22 23 24 25 26 27
  27 28 29 30 31             24 25 26 27 28 29 30       28 29 30            
                             31                                             
        October                    November                   December      
  Su Mo Tu We Th Fr Sa       Su Mo Tu We Th Fr Sa       Su Mo Tu We Th Fr Sa
            1  2  3  4                          1           1  2  3  4  5  6
   5  6  7  8  9 10 11        2  3  4  5  6  7  8        7  8  9 10 11 12 13
  12 13 14 15 16 17 18        9 10 11 12 13 14 15       14 15 16 17 18 19 20
  19 20 21 22 23 24 25       16 17 18 19 20 21 22       21 22 23 24 25 26 27
  26 27 28 29 30 31          23 24 25 26 27 28 29       28 29 30 31         
                             30                                             

AutoHotkey

<lang AutoHotkey>Calendar(Yr){ LastDay := [] Day := []

Titles = (ltrim ______January_________________February_________________March_______ _______April____________________May____________________June________ ________July___________________August_________________September_____ ______October_________________November________________December______ ) StringSplit, title, titles, `n Res := "________________________________" Yr "`r`n"

loop 4 ; 4 Vertical Sections { Day[1]:=Yr SubStr("0" A_Index*3 -2, -1) 01, Day[2]:=Yr SubStr("0" A_Index*3 -1, -1) 01, Day[3]:=Yr SubStr("0" A_Index*3 , -1) 01 Res .= "`r`n" title%A_Index% "`r`nSu Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa" loop , 6 ; 6 Weeks max per month { Week := A_Index , Res .= "`r`n" loop, 21 ; 3 weeks times 7 days { Mon := Ceil(A_Index/7), ThisWD := Mod(A_Index-1,7)+1 FormatTime, WD, % Day[Mon], WDay FormatTime, dd, % Day[Mon], dd if (WD>ThisWD) { Res .= "__ " continue } dd := ((Week>3) && dd <10) ? "__" : dd, Res .= dd " ", LastDay[Mon] := Day[Mon], Day[Mon] +=1, Days Res .= ((wd=7) && A_Index < 21) ? "___" : "" FormatTime, dd, % Day[Mon], dd } } Res .= "`r`n" } StringReplace, Res, Res,_,%A_Space%, all StringReplace, Res, Res,%A_Space%0,%A_Space%%A_Space%, all return res }</lang> Examples:<lang AutoHotkey>Gui, font,s8, COURIER Gui, add, edit, vYr w40 r1 Limit4 Number, 1969 Gui, add, edit, vEdit2 w580 r38 Gui, Add, Button, Default Hidden gSubmit Gui, show

Submit: Gui, Submit, NoHide GuiControl,, Edit2, % Calendar(Yr) return

GuiEscape: GuiClose: ExitApp return</lang>

Outputs:

                                1969

      January                 February                 March       
Su Mo Tu We Th Fr Sa    Su Mo Tu We Th Fr Sa    Su Mo Tu We Th Fr Sa
          1  2  3  4                       1                       1 
05  6  7  8  9 10 11     2  3  4  5  6  7  8     2  3  4  5  6  7  8 
12 13 14 15 16 17 18     9 10 11 12 13 14 15     9 10 11 12 13 14 15 
19 20 21 22 23 24 25    16 17 18 19 20 21 22    16 17 18 19 20 21 22 
26 27 28 29 30 31       23 24 25 26 27 28       23 24 25 26 27 28 29 
                                                30 31                

       April                    May                    June        
Su Mo Tu We Th Fr Sa    Su Mo Tu We Th Fr Sa    Su Mo Tu We Th Fr Sa
       1  2  3  4  5                 1  2  3     1  2  3  4  5  6  7 
06  7  8  9 10 11 12     4  5  6  7  8  9 10     8  9 10 11 12 13 14 
13 14 15 16 17 18 19    11 12 13 14 15 16 17    15 16 17 18 19 20 21 
20 21 22 23 24 25 26    18 19 20 21 22 23 24    22 23 24 25 26 27 28 
27 28 29 30             25 26 27 28 29 30 31    29 30                
                                                                     

        July                   August                 September     
Su Mo Tu We Th Fr Sa    Su Mo Tu We Th Fr Sa    Su Mo Tu We Th Fr Sa
       1  2  3  4  5                    1  2        1  2  3  4  5  6 
06  7  8  9 10 11 12     3  4  5  6  7  8  9     7  8  9 10 11 12 13 
13 14 15 16 17 18 19    10 11 12 13 14 15 16    14 15 16 17 18 19 20 
20 21 22 23 24 25 26    17 18 19 20 21 22 23    21 22 23 24 25 26 27 
27 28 29 30 31          24 25 26 27 28 29 30    28 29 30             
                        31                                           

      October                 November                December      
Su Mo Tu We Th Fr Sa    Su Mo Tu We Th Fr Sa    Su Mo Tu We Th Fr Sa
          1  2  3  4                       1        1  2  3  4  5  6 
05  6  7  8  9 10 11     2  3  4  5  6  7  8     7  8  9 10 11 12 13 
12 13 14 15 16 17 18     9 10 11 12 13 14 15    14 15 16 17 18 19 20 
19 20 21 22 23 24 25    16 17 18 19 20 21 22    21 22 23 24 25 26 27 
26 27 28 29 30 31       23 24 25 26 27 28 29    28 29 30 31          
                        30                                           

AutoIt

<lang AutoIt>

  1. include <Date.au3>
Set the count of characters in each line, minimum is 20 - one month.

Global $iPrintSize = 132

Set the count of months, you want to print side by side. With "0" it calculates automatically.
The number will corrected, if it not allowed to print in an rectangle.
If your print size is to small for given count, it will set back to automatically calculation.

Global $iSideBySide = 3

Set the count of spaces between months.

Global $iSpace = 4

_CreateCalendar( 1969 )


Func _CreateCalendar($_iYear) Local $aMon[12] = [' January ', ' February ', ' March ', _ ' April ', ' May ', ' June ', _ ' July ', ' August ', ' September ', _ ' October ', ' November ', ' December '] Local $sHead = 'Mo Tu We Th Fr Sa Su' Local $aDaysInMonth[12] = [31,28,31,30,31,30,31,31,30,31,30,31] If _DateIsLeapYear($_iYear) Then $aDaysInMonth[1] = 29

; == assign date in weekday table for the whole year Local $aAllDaysInMonth[6][7][12]  ; [ lines ][ weekdays ][ months ] Local $iDay = 1, $iShift For $i = 1 To 12 $iShift = _DateToDayOfWeekISO($_iYear, $i, 1) -1 For $j = 0 To 5 For $k = $iShift To 6 $aAllDaysInMonth[$j][$k][$i-1] = $iDay $iDay += 1 If $iDay > $aDaysInMonth[$i-1] Then ExitLoop(2) Next $iShift = 0 Next $iDay = 1 Next

; == check given side by side count, calculate if needed If $iSideBySide > 0 Then If $iPrintSize < ($iSideBySide *(20 +$iSpace) -$iSpace) Then $iSideBySide = 0 EndIf Switch $iSideBySide Case 0 $iSideBySide = Int($iPrintSize /(20 +$iSpace)) If $iPrintSize < 20 Then Return _PrintLine('Escape: Size Error') If $iPrintSize < (20 +$iSpace) Then $iSideBySide = 1 Case 5 $iSideBySide = 4 Case 7 To 11 $iSideBySide = 6 EndSwitch

; == create space string Local $sSpace = For $i = 1 To $iSpace $sSpace &= ' ' Next

; == print header _PrintLine(@LF) _PrintLine('[ here is Snoopy ]', @LF) _PrintLine(StringRegExpReplace($_iYear, '(\d)(\d)(\d)(\d)', '$1 $2 $3 $4'), @LF)

; == create data for each line, in dependence to count of months in one line Local $sLine, $iRight, $sTmp1, $sTmp2 For $n = 0 To 12 /$iSideBySide -1 $sTmp1 = $sTmp2 = For $z = 0 To $iSideBySide -1 $sTmp1 &= $aMon[$iSideBySide *$n+$z] & $sSpace $sTmp2 &= $sHead & $sSpace Next _PrintLine(StringTrimRight($sTmp1, $iSpace)) _PrintLine(StringTrimRight($sTmp2, $iSpace)) For $j = 0 To 5 $sLine = For $i = 1 To $iSideBySide For $k = 0 To 6 $iRight = 3 If $k = 0 Then $iRight = 2 $sLine &= StringRight(' ' & $aAllDaysInMonth[$j][$k][$iSideBySide*$n+$i-1], $iRight) Next If $i < $iSideBySide Then $sLine &= $sSpace Next _PrintLine($sLine) Next Next EndFunc  ;==>_CreateCalendar

Func _PrintLine($_sLine, $_sLF=) Local $iLen = StringLen($_sLine) Local $sSpace = , $sLeft = For $i = 1 To $iPrintSize-1 $sSpace &= ' ' Next If $iLen < $iPrintSize Then $sLeft = StringLeft($sSpace, Int(($iPrintSize-$iLen)/2)) ConsoleWrite($sLeft & $_sLine & $_sLF & @LF) EndFunc  ;==>_PrintLine </lang> Output

                                                                

                                                         [ here is Snoopy ]

                                                              1 9 6 9

                                       January                February                  March       
                                Mo Tu We Th Fr Sa Su    Mo Tu We Th Fr Sa Su    Mo Tu We Th Fr Sa Su
                                       1  2  3  4  5                    1  2                    1  2
                                 6  7  8  9 10 11 12     3  4  5  6  7  8  9     3  4  5  6  7  8  9
                                13 14 15 16 17 18 19    10 11 12 13 14 15 16    10 11 12 13 14 15 16
                                20 21 22 23 24 25 26    17 18 19 20 21 22 23    17 18 19 20 21 22 23
                                27 28 29 30 31          24 25 26 27 28          24 25 26 27 28 29 30
                                                                                31                  
                                        April                    May                    June        
                                Mo Tu We Th Fr Sa Su    Mo Tu We Th Fr Sa Su    Mo Tu We Th Fr Sa Su
                                    1  2  3  4  5  6              1  2  3  4                       1
                                 7  8  9 10 11 12 13     5  6  7  8  9 10 11     2  3  4  5  6  7  8
                                14 15 16 17 18 19 20    12 13 14 15 16 17 18     9 10 11 12 13 14 15
                                21 22 23 24 25 26 27    19 20 21 22 23 24 25    16 17 18 19 20 21 22
                                28 29 30                26 27 28 29 30 31       23 24 25 26 27 28 29
                                                                                30                  
                                        July                   August                 September     
                                Mo Tu We Th Fr Sa Su    Mo Tu We Th Fr Sa Su    Mo Tu We Th Fr Sa Su
                                    1  2  3  4  5  6                 1  2  3     1  2  3  4  5  6  7
                                 7  8  9 10 11 12 13     4  5  6  7  8  9 10     8  9 10 11 12 13 14
                                14 15 16 17 18 19 20    11 12 13 14 15 16 17    15 16 17 18 19 20 21
                                21 22 23 24 25 26 27    18 19 20 21 22 23 24    22 23 24 25 26 27 28
                                28 29 30 31             25 26 27 28 29 30 31    29 30               
                                                                                                    
                                       October                November                December      
                                Mo Tu We Th Fr Sa Su    Mo Tu We Th Fr Sa Su    Mo Tu We Th Fr Sa Su
                                       1  2  3  4  5                    1  2     1  2  3  4  5  6  7
                                 6  7  8  9 10 11 12     3  4  5  6  7  8  9     8  9 10 11 12 13 14
                                13 14 15 16 17 18 19    10 11 12 13 14 15 16    15 16 17 18 19 20 21
                                20 21 22 23 24 25 26    17 18 19 20 21 22 23    22 23 24 25 26 27 28
                                27 28 29 30 31          24 25 26 27 28 29 30    29 30 31            
                                                                                                                                                 

--BugFix (talk) 00:40, 15 November 2013 (UTC)

AWK

<lang AWK>

Works with Gnu awk version 3.1.5 and with BusyBox v1.20.0.git awk To change the output width, change the value assigned to variable pagewide

  1. !/bin/gawk -f

BEGIN{

 wkdays = "Su Mo Tu We Th Fr Sa"
 pagewide = 80
 blank=" "
 for (i=1; i<pagewide; i++) blank = blank " "
 #  month name accessed as substr(month,num*10,10) 
 #      where num is number of month, 1-12
 month= "           January  February    March     April  "
 month=    month "   May      June       July     August  "
 month=    month " September October   November  December "
 #  table of days per month accessed as substr(days,2*month,2)
 days =" 312831303130313130313031"
 line1 = ""
 line2 = ""
 line3 = ""
 line4 = ""
 line5 = ""
 line6 = ""
 line7 = ""
 line8 = ""
  1. print " year: " year " starts on: " dow(year)
 }

function center(text, half) {

 half = (pagewide - length(text))/2
 return substr(blank,1,half) text substr(blank,1,half)
 }

function min(a,b) {

 if (a < b) return a
 else return b
 }

function makewk (fst,lst,day, i,wstring ){

 wstring=""
 for (i=1;i<day;i++) wstring=wstring "   "
 for (i=fst;i<=lst;i++) wstring=wstring sprintf("%2d ",i)
 return substr(wstring "                     ",1,20)
 }

function dow (year, y){

 y=year
 y= (y*365+int(y/4) - int(y/100) + int(y/400) +1) %7
  1. leap year adjustment
 leap = 0
 if (year % 4 == 0)   leap = 1
 if (year % 100 == 0) leap = 0
 if (year % 400 == 0) leap = 1
 y = y - leap
 if (y==-1) y=6
 if (y==0) y=7
 return (y)
 }

function prmonth (nmonth, newdow,monsize ){

 line1 = line1  "     " (substr(month,10*nmonth,10)) "       "
 line2 = line2  (wkdays) "  "
 line3 = line3  (makewk(1,8-newdow,newdow)) "  "
 line4 = line4  (makewk(9-newdow,15-newdow,1)) "  "
 line5 = line5  (makewk(16-newdow,22-newdow,1)) "  "
 line6 = line6  (makewk(23-newdow,29-newdow,1)) "  "
 line7 = line7  (makewk(30-newdow,min(monsize,36-newdow),1)) "  "
 line8 = line8  (makewk(37-newdow,monsize,1)) "  "

if (length(line3) + 22 > pagewide) {

 print center(line1)
 print center(line2)
 print center(line3)
 print center(line4)
 print center(line5)
 print center(line6)
 print center(line7)
 print center(line8)
 line1 = ""
 line2 = ""
 line3 = ""
 line4 = ""
 line5 = ""
 line6 = ""
 line7 = ""
 line8 = ""
 }

} /q/{

 exit }

{

 monsize=substr(days,2*1,2)
 newdow=dow($1)
 print center("[ picture of Snoopy goes here ]")
 print center(sprintf("%d",$1)  )
 # January - December
 for (i=1; i<13; i++) {
 prmonth(i,newdow,monsize)
 newdow=(monsize+newdow) %7
 if (newdow == 0) newdow = 7
 monsize=substr(days,2+2*i,2)
 if (leap == 1 && monsize == 28) monsize = 29
 }
}
   

</lang> Output:

                        [ picture of Snoopy goes here ]                        
                                      1969                                      
              January              February                March                
       Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa         
                 1  2  3  4                     1                     1         
        5  6  7  8  9 10 11   2  3  4  5  6  7  8   2  3  4  5  6  7  8         
       12 13 14 15 16 17 18   9 10 11 12 13 14 15   9 10 11 12 13 14 15         
       19 20 21 22 23 24 25  16 17 18 19 20 21 22  16 17 18 19 20 21 22         
       26 27 28 29 30 31     23 24 25 26 27 28     23 24 25 26 27 28 29         
                                                   30 31                        
               April                 May                  June                  
       Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa         
              1  2  3  4  5               1  2  3   1  2  3  4  5  6  7         
        6  7  8  9 10 11 12   4  5  6  7  8  9 10   8  9 10 11 12 13 14         
       13 14 15 16 17 18 19  11 12 13 14 15 16 17  15 16 17 18 19 20 21         
       20 21 22 23 24 25 26  18 19 20 21 22 23 24  22 23 24 25 26 27 28         
       27 28 29 30           25 26 27 28 29 30 31  29 30                        
                                                                                
               July                 August               September              
       Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa         
              1  2  3  4  5                  1  2      1  2  3  4  5  6         
        6  7  8  9 10 11 12   3  4  5  6  7  8  9   7  8  9 10 11 12 13         
       13 14 15 16 17 18 19  10 11 12 13 14 15 16  14 15 16 17 18 19 20         
       20 21 22 23 24 25 26  17 18 19 20 21 22 23  21 22 23 24 25 26 27         
       27 28 29 30 31        24 25 26 27 28 29 30  28 29 30                     
                             31                                                 
             October               November              December               
       Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa         
                 1  2  3  4                     1      1  2  3  4  5  6         
        5  6  7  8  9 10 11   2  3  4  5  6  7  8   7  8  9 10 11 12 13         
       12 13 14 15 16 17 18   9 10 11 12 13 14 15  14 15 16 17 18 19 20         
       19 20 21 22 23 24 25  16 17 18 19 20 21 22  21 22 23 24 25 26 27         
       26 27 28 29 30 31     23 24 25 26 27 28 29  28 29 30 31                  
                             30                                                 

BBC BASIC

The day and month names are in the language for which the PC is configured. <lang bbcbasic> INSTALL @lib$+"DATELIB"

     VDU 23,22,640;570;8,15,16,128
     
     year% = 1969
     PRINT TAB(38); year%
     DIM dom%(2), mjd%(2), dim%(2)
     
     FOR day% = 1 TO 7
       days$ += LEFT$(FN_date$(FN_mjd(day%, 1, 1905), "ddd"), 2) + " "
     NEXT
     
     FOR month% = 1 TO 10 STEP 3
       PRINT
       FOR col% = 0 TO 2
         mjd%(col%) = FN_mjd(1, month% + col%, year%)
         month$ = FN_date$(mjd%(col%), "MMMM")
         PRINT TAB(col%*24 + 16 - LEN(month$)/2) month$;
       NEXT
       FOR col% = 0 TO 2
         PRINT TAB(col%*24 + 6) days$;
         dim%(col%) = FN_dim(month% + col%, year%)
       NEXT
       dom%() = 1
       col% = 0
       REPEAT
         dow% = FN_dow(mjd%(col%))
         IF dom%(col%)<=dim%(col%) THEN
           PRINT TAB(col%*24 + dow%*3 + 6); dom%(col%);
           dom%(col%) += 1
           mjd%(col%) += 1
         ENDIF
         IF dow%=6 OR dom%(col%)>dim%(col%) col% = (col% + 1) MOD 3
       UNTIL dom%(0)>dim%(0) AND dom%(1)>dim%(1) AND dom%(2)>dim%(2)
       PRINT
     NEXT

</lang> Output:

                                      1969

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

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

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

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

C

With arbitrary display width (>= 20 though) and auto spacing. <lang C>#include <stdio.h>

  1. include <stdlib.h>
  2. include <string.h>

int width = 80, year = 1969; int cols, lead, gap;

const char *wdays[] = { "Su", "Mo", "Tu", "We", "Th", "Fr", "Sa" }; struct months { const char *name; int days, start_wday, at; } months[12] = { { "January", 31, 0, 0 }, { "Februray", 28, 0, 0 }, { "March", 31, 0, 0 }, { "April", 30, 0, 0 }, { "May", 31, 0, 0 }, { "June", 30, 0, 0 }, { "July", 31, 0, 0 }, { "August", 31, 0, 0 }, { "September", 30, 0, 0 }, { "October", 31, 0, 0 }, { "November", 30, 0, 0 }, { "December", 31, 0, 0 } };

void space(int n) { while (n-- > 0) putchar(' '); }

void init_months() { int i;

if ((!(year % 4) && (year % 100)) || !(year % 400)) months[1].days = 29;

year--; months[0].start_wday = (year * 365 + year/4 - year/100 + year/400 + 1) % 7;

for (i = 1; i < 12; i++) months[i].start_wday = (months[i-1].start_wday + months[i-1].days) % 7;

cols = (width + 2) / 22; while (12 % cols) cols--; gap = cols - 1 ? (width - 20 * cols) / (cols - 1) : 0; if (gap > 4) gap = 4; lead = (width - (20 + gap) * cols + gap + 1) / 2;

       year++;

}

void print_row(int row) { int c, i, from = row * cols, to = from + cols; space(lead); for (c = from; c < to; c++) { i = strlen(months[c].name); space((20 - i)/2); printf("%s", months[c].name); space(20 - i - (20 - i)/2 + ((c == to - 1) ? 0 : gap)); } putchar('\n');

space(lead); for (c = from; c < to; c++) { for (i = 0; i < 7; i++) printf("%s%s", wdays[i], i == 6 ? "" : " "); if (c < to - 1) space(gap); else putchar('\n'); }

while (1) { for (c = from; c < to; c++) if (months[c].at < months[c].days) break; if (c == to) break;

space(lead); for (c = from; c < to; c++) { for (i = 0; i < months[c].start_wday; i++) space(3); while(i++ < 7 && months[c].at < months[c].days) { printf("%2d", ++months[c].at); if (i < 7 || c < to - 1) putchar(' '); } while (i++ <= 7 && c < to - 1) space(3); if (c < to - 1) space(gap - 1); months[c].start_wday = 0; } putchar('\n'); } putchar('\n'); }

void print_year() { int row; char buf[32]; sprintf(buf, "%d", year); space((width - strlen(buf)) / 2); printf("%s\n\n", buf); for (row = 0; row * cols < 12; row++) print_row(row); }

int main(int c, char **v) { int i, year_set = 0; for (i = 1; i < c; i++) { if (!strcmp(v[i], "-w")) { if (++i == c || (width = atoi(v[i])) < 20) goto bail; } else if (!year_set) { if (!sscanf(v[i], "%d", &year) || year <= 0) year = 1969; year_set = 1; } else goto bail; }

init_months(); print_year(); return 0;

bail: fprintf(stderr, "bad args\nUsage: %s year [-w width (>= 20)]\n", v[0]); exit(1); }</lang>

C++

<lang cpp>

  1. include <windows.h>
  2. include <iostream>

//-------------------------------------------------------------------------------------------------- using namespace std;


//-------------------------------------------------------------------------------------------------- class calender { public:

   void drawCalender( int y )
   {

year = y; for( int i = 0; i < 12; i++ ) firstdays[i] = getfirstday( i );

isleapyear(); build();

   }

private:

   void isleapyear()
   {

isleap = false;

if( !( year % 4 ) ) { if( year % 100 ) isleap = true; else if( !( year % 400 ) ) isleap = true; }

   }
   int getfirstday( int m )
   {

int y = year;

int f = y + 1 + 3 * m - 1; m++; if( m < 3 ) y--; else f -= int( .4 * m + 2.3 );

f += int( y / 4 ) - int( ( y / 100 + 1 ) * 0.75 ); f %= 7;

return f;

   }
   void build()
   {

int days[] = { 31, isleap ? 29 : 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }; int lc = 0, lco = 0, ystr = 7, start = 2, fd = 0, m = 0; HANDLE h = GetStdHandle( STD_OUTPUT_HANDLE ); COORD pos = { 0, ystr }; draw();

for( int i = 0; i < 4; i++ ) { for( int j = 0; j < 3; j++ ) { int d = firstdays[fd++], dm = days[m++]; pos.X = d * 3 + start; SetConsoleCursorPosition( h, pos );

for( int dd = 0; dd < dm; dd++ ) { if( dd < 9 ) cout << 0 << dd + 1 << " "; else cout << dd + 1 << " ";

pos.X += 3; if( pos.X - start > 20 ) { pos.X = start; pos.Y++; SetConsoleCursorPosition( h, pos ); } }

start += 23; pos.X = start; pos.Y = ystr; SetConsoleCursorPosition( h, pos ); } ystr += 9; start = 2; pos.Y = ystr; }

   }
   void draw()
   {

system( "cls" ); cout << "+--------------------------------------------------------------------+" << endl; cout << "| [SNOOPY] |" << endl; cout << "| |" << endl; cout << "| == " << year << " == |" << endl; cout << "+----------------------+----------------------+----------------------+" << endl; cout << "| JANUARY | FEBRUARY | MARCH |" << endl; cout << "| SU MO TU WE TH FR SA | SU MO TU WE TH FR SA | SU MO TU WE TH FR SA |" << endl; cout << "| | | |" << endl; cout << "| | | |" << endl; cout << "| | | |" << endl; cout << "| | | |" << endl; cout << "| | | |" << endl; cout << "| | | |" << endl; cout << "+----------------------+----------------------+----------------------+" << endl; cout << "| APRIL | MAY | JUNE |" << endl; cout << "| SU MO TU WE TH FR SA | SU MO TU WE TH FR SA | SU MO TU WE TH FR SA |" << endl; cout << "| | | |" << endl; cout << "| | | |" << endl; cout << "| | | |" << endl; cout << "| | | |" << endl; cout << "| | | |" << endl; cout << "| | | |" << endl; cout << "+----------------------+----------------------+----------------------+" << endl; cout << "| JULY | AUGUST | SEPTEMBER |" << endl; cout << "| SU MO TU WE TH FR SA | SU MO TU WE TH FR SA | SU MO TU WE TH FR SA |" << endl; cout << "| | | |" << endl; cout << "| | | |" << endl; cout << "| | | |" << endl; cout << "| | | |" << endl; cout << "| | | |" << endl; cout << "| | | |" << endl; cout << "+----------------------+----------------------+----------------------+" << endl; cout << "| OCTOBER | NOVEMBER | DECEMBER |" << endl; cout << "| SU MO TU WE TH FR SA | SU MO TU WE TH FR SA | SU MO TU WE TH FR SA |" << endl; cout << "| | | |" << endl; cout << "| | | |" << endl; cout << "| | | |" << endl; cout << "| | | |" << endl; cout << "| | | |" << endl; cout << "| | | |" << endl; cout << "+----------------------+----------------------+----------------------+" << endl;

   }
   int firstdays[12], year;
   bool isleap;

}; //-------------------------------------------------------------------------------------------------- int main( int argc, char* argv[] ) {

   int y;
   calender cal;
   while( true )
   {

system( "cls" ); cout << "Enter the year( yyyy ) --- ( 0 to quit ): "; cin >> y; if( !y ) return 0;

cal.drawCalender( y ); cout << endl << endl << endl << endl << endl << endl << endl << endl;

system( "pause" );

   }
   return 0;

} //-------------------------------------------------------------------------------------------------- </lang> Output:

+--------------------------------------------------------------------+
|                              [SNOOPY]                              |
|                                                                    |
|                             == 1969 ==                             |
+----------------------+----------------------+----------------------+
|       JANUARY        |       FEBRUARY       |         MARCH        |
| SU MO TU WE TH FR SA | SU MO TU WE TH FR SA | SU MO TU WE TH FR SA |
|          01 02 03 04 |                   01 |                   01 |
| 05 06 07 08 09 10 11 | 02 03 04 05 06 07 08 | 02 03 04 05 06 07 08 |
| 12 13 14 15 16 17 18 | 09 10 11 12 13 14 15 | 09 10 11 12 13 14 15 |
| 19 20 21 22 23 24 25 | 16 17 18 19 20 21 22 | 16 17 18 19 20 21 22 |
| 26 27 28 29 30 31    | 23 24 25 26 27 28    | 23 24 25 26 27 28 29 |
|                      |                      | 30 31                |
+----------------------+----------------------+----------------------+
|        APRIL         |          MAY         |         JUNE         |
| SU MO TU WE TH FR SA | SU MO TU WE TH FR SA | SU MO TU WE TH FR SA |
|       01 02 03 04 05 |             01 02 03 | 01 02 03 04 05 06 07 |
| 06 07 08 09 10 11 12 | 04 05 06 07 08 09 10 | 08 09 10 11 12 13 14 |
| 13 14 15 16 17 18 19 | 11 12 13 14 15 16 17 | 15 16 17 18 19 20 21 |
| 20 21 22 23 24 25 26 | 18 19 20 21 22 23 24 | 22 23 24 25 26 27 28 |
| 27 28 29 30          | 25 26 27 28 29 30 31 | 29 30                |
|                      |                      |                      |
+----------------------+----------------------+----------------------+
|         JULY         |        AUGUST        |       SEPTEMBER      |
| SU MO TU WE TH FR SA | SU MO TU WE TH FR SA | SU MO TU WE TH FR SA |
|       01 02 03 04 05 |                01 02 |    01 02 03 04 05 06 |
| 06 07 08 09 10 11 12 | 03 04 05 06 07 08 09 | 07 08 09 10 11 12 13 |
| 13 14 15 16 17 18 19 | 10 11 12 13 14 15 16 | 14 15 16 17 18 19 20 |
| 20 21 22 23 24 25 26 | 17 18 19 20 21 22 23 | 21 22 23 24 25 26 27 |
| 27 28 29 30 31       | 24 25 26 27 28 29 30 | 28 29 30             |
|                      | 31                   |                      |
+----------------------+----------------------+----------------------+
|        OCTOBER       |       NOVEMBER       |       DECEMBER       |
| SU MO TU WE TH FR SA | SU MO TU WE TH FR SA | SU MO TU WE TH FR SA |
|          01 02 03 04 |                   01 |    01 02 03 04 05 06 |
| 05 06 07 08 09 10 11 | 02 03 04 05 06 07 08 | 07 08 09 10 11 12 13 |
| 12 13 14 15 16 17 18 | 09 10 11 12 13 14 15 | 14 15 16 17 18 19 20 |
| 19 20 21 22 23 24 25 | 16 17 18 19 20 21 22 | 21 22 23 24 25 26 27 |
| 26 27 28 29 30 31    | 23 24 25 26 27 28 29 | 28 29 30 31          |
|                      | 30                   |                      |
+----------------------+----------------------+----------------------+

C#

An attempt to abuse the DateTime class for all static information. In the event that the number of days and months changes, so long as the DateTime class is updated accordingly, this should still print properly. It also abuses iterators to allow for a concise month printing method, but with the ability to still print x months per line.

<lang csharp>

using System; using System.Collections.Generic; using System.Linq; using System.Text;

namespace CalendarStuff {

   class Program
   {
       static void Main(string[] args)
       {
           Console.WindowHeight = 46;
           Console.Write(buildMonths(new DateTime(1969, 1, 1)));
           Console.Read(); 
       }
       private static string buildMonths(DateTime date)
       {
           StringBuilder sb = new StringBuilder();
           sb.AppendLine(center("[Snoop]", 24 * 3));
           sb.AppendLine();
           sb.AppendLine(center(date.Year.ToString(), 24 * 3));
           List<DateTime> dts = new List<DateTime>();
           while (true)
           {
               dts.Add(date);
               if (date.Year != ((date = date.AddMonths(1)).Year))
               {
                   break;
               }
           }
           var jd = dts.Select(a => buildMonth(a).GetEnumerator()).ToArray();
           
           int sCur=0;
           while (sCur<dts.Count)
           {
               sb.AppendLine();
               int curMonth=0; 
               var j = jd.Where(a => curMonth++ >= sCur && curMonth - 1 < sCur + 3).ToArray(); //grab the next 3
               sCur += j.Length; 
               bool breakOut = false;
               while (!breakOut)
               {
                   int inj = 1;
                   foreach (var cd in j)
                   {
                       if (cd.MoveNext())
                       {
                           sb.Append((cd.Current.Length == 21 ? cd.Current : cd.Current.PadRight(21, ' ')) + "     ");
                       }
                       else
                       {
                           sb.Append("".PadRight(21, ' ') + "     ");
                           breakOut = true;
                       }
                       if (inj++ % 3 == 0) sb.AppendLine();
                   }
               }
           }
           return sb.ToString();
       }


       private static IEnumerable<string> buildMonth(DateTime date)
       {
           yield return center(date.ToString("MMMM"),7*3);
           var j = DateTime.DaysInMonth(date.Year, date.Month);
           yield return Enum.GetNames(typeof(DayOfWeek)).Aggregate("", (current, result) => current + (result.Substring(0, 2).ToUpper() + " "));
           string cur = "";
           int total = 0;
           foreach (var day in Enumerable.Range(-((int)date.DayOfWeek),j + (int)date.DayOfWeek))
           {
               cur += (day < 0 ? "  " : ((day < 9 ? " " : "") + (day + 1))) +" ";
               if (total++ > 0 && (total ) % 7 == 0)
               {
                   yield return cur;
                   cur = "";
               }
           }
           yield return cur;
       }
       private static string center(string s, int len)
       {
           return (s.PadLeft((len - s.Length) / 2 + s.Length, ' ').PadRight((len), ' '));
       } 
   }

}

</lang>

COBOL

the program calls subroutine DATE2DOW to convert any YYYY-MM-DD to Day of Week (1=Sunday). the group names WS-CFGN and WS-CFGW may be moved to WS-CFG to use narrow or wide print line size respectively. <lang COBOL>

      IDENTIFICATION DIVISION.
      PROGRAM-ID.  CALEND.
      ENVIRONMENT DIVISION.
      INPUT-OUTPUT SECTION.
      DATA DIVISION.

      WORKING-STORAGE SECTION.
      01  WS-DAY-NAMES-DEF.
        03 FILLER PIC X(09) VALUE 'SUNDAY   '.
        03 FILLER PIC X(09) VALUE 'MONDAY   '.
        03 FILLER PIC X(09) VALUE 'TUESDAY  '.
        03 FILLER PIC X(09) VALUE 'WEDNESDAY'.
        03 FILLER PIC X(09) VALUE 'THURSDAY '.
        03 FILLER PIC X(09) VALUE 'FRIDAY   '.
        03 FILLER PIC X(09) VALUE 'SATURDAY '.
      01  FILLER REDEFINES WS-DAY-NAMES-DEF.
        03  WS-DAY-NAME       PIC X(09) OCCURS 07 TIMES.

      01  WS-MTH-INFO-DEF.
        03 FILLER PIC X(11) VALUE 'JANUARY  31'.
        03 FILLER PIC X(11) VALUE 'FEBRUARY 28'.
        03 FILLER PIC X(11) VALUE 'MARCH    31'.
        03 FILLER PIC X(11) VALUE 'APRIL    30'.
        03 FILLER PIC X(11) VALUE 'MAY      31'.
        03 FILLER PIC X(11) VALUE 'JUNE     30'.
        03 FILLER PIC X(11) VALUE 'JULY     31'.
        03 FILLER PIC X(11) VALUE 'AUGUST   31'.
        03 FILLER PIC X(11) VALUE 'SEPTEMBER30'.
        03 FILLER PIC X(11) VALUE 'OCTOBER  31'.
        03 FILLER PIC X(11) VALUE 'NOVEMBER 30'.
        03 FILLER PIC X(11) VALUE 'DECEMBER 31'.
      01  FILLER REDEFINES WS-MTH-INFO-DEF.
        03  WS-MTH-INFO-TABLE OCCURS 12 TIMES.
          05  WS-MTH-INFO-NAME   PIC X(09).
          05  WS-MTH-INFO-DAYS   PIC 9(02).
      01  WS-MTH-AREA.
        03  WS-MTH-DD         PIC S99.
        03  WS-DAY1           PIC   9.
        03  WS-DAYS           PIC  99.
        03  WS-DD             PIC   9.
        03  WS-WK             PIC   9.
        03  WS-MM             PIC  99.
        03  WS-QQ             PIC  99.

        03  WS-MTH-MONTH  OCCURS 12 TIMES.
          05  WS-MTH-WEEK OCCURS 6 TIMES.
            07  WS-DAY-FLD      OCCURS 7 TIMES.
              09  WS-DAY        PIC ZZ.
      01  INPDATE-RECORD.
          05  INPD-YEAR          PIC 9(04).
          05  FILLER             PIC X(01).
          05  INPD-MONTH         PIC 9(02).
          05  FILLER             PIC X(01).
          05  INPD-DAY           PIC 9(02).
      01  WMS-DOW                PIC 9(01).
      01  WS-PRT                 PIC X(132).
      01  WS-COL                 PIC  9(03) VALUE 0.
      01  WS-PP                  PIC  9(03) VALUE 0.
      01  WS-CFGN.
        03  FILLER               PIC  9(03) VALUE  80.
        03  FILLER               PIC  9(02) VALUE  5.
        03  FILLER               PIC  9(01) VALUE  1.
        03  FILLER               PIC  9(02) VALUE  5.
        03  FILLER               PIC  9(01) VALUE  2.
      01  WS-CFGW.
        03  FILLER               PIC  9(03) VALUE 120.
        03  FILLER               PIC  9(02) VALUE 10.
        03  FILLER               PIC  9(01) VALUE  2.
        03  FILLER               PIC  9(02) VALUE 10.
        03  FILLER               PIC  9(01) VALUE  3.
      01  WS-CFG.
        03  WS-LS                PIC  9(03) VALUE 120.
        03  WS-LMAR              PIC  9(02) VALUE 10.
        03  WS-SPBD              PIC  9(01) VALUE  2.
        03  WS-SPBC              PIC  9(02) VALUE 10.
        03  WS-DNMW              PIC  9(01) VALUE  3.
      PROCEDURE DIVISION.
          MOVE '1969-01-01' TO INPDATE-RECORD
          MOVE WS-CFGN   TO WS-CFG
          IF  (FUNCTION MOD ( INPD-YEAR , 400 ) = 0
          OR  (FUNCTION MOD ( INPD-YEAR , 4   ) = 0
              AND
              FUNCTION MOD ( INPD-YEAR , 100 ) NOT = 0))
            MOVE 29         TO WS-MTH-INFO-DAYS (02)
          ELSE
            MOVE 28         TO WS-MTH-INFO-DAYS (02)
          END-IF

          PERFORM VARYING WS-MM FROM 1 BY +1
          UNTIL WS-MM > 12
          MOVE WS-MM TO INPD-MONTH
          CALL 'DATE2DOW' USING INPDATE-RECORD, WMS-DOW
          COMPUTE WS-MTH-DD = 1 - WMS-DOW
          COMPUTE WS-DAYS = WS-MTH-INFO-DAYS (INPD-MONTH)
          PERFORM VARYING WS-WK FROM 1 BY +1
          UNTIL WS-WK > 6
            PERFORM VARYING WS-DD FROM 1 BY +1
            UNTIL WS-DD > 7
              COMPUTE WS-MTH-DD = WS-MTH-DD + 1
              IF (WS-MTH-DD < 1)
              OR (WS-MTH-DD > WS-DAYS)
                MOVE 0         TO WS-DAY (WS-MM, WS-WK, WS-DD)
              ELSE
                MOVE WS-MTH-DD TO WS-DAY (WS-MM, WS-WK, WS-DD)
              END-IF
            END-PERFORM
          END-PERFORM
          END-PERFORM

          COMPUTE WS-MM = 0
          PERFORM VARYING WS-QQ FROM 1 BY +1
          UNTIL WS-QQ > 4

            INITIALIZE WS-PRT
            COMPUTE WS-PP = 1
            PERFORM VARYING WS-COL FROM 1 BY +1
            UNTIL WS-COL > 3
            COMPUTE WS-MM = 3 * (WS-QQ - 1) + WS-COL

              IF WS-COL = 1
                COMPUTE WS-PP = WS-PP + WS-LMAR + 2 - WS-DNMW
              ELSE
                COMPUTE WS-PP = WS-PP + WS-SPBC + 2 - WS-DNMW
              END-IF
              MOVE WS-MTH-INFO-NAME (WS-MM)
                            TO WS-PRT(WS-PP:9)
              COMPUTE WS-PP
              =       WS-PP + ( 2 * 7 + WS-SPBD * 6 + WS-SPBD - 1)
              -       4
              MOVE INPD-YEAR TO WS-PRT (WS-PP:4)
              COMPUTE WS-PP = WS-PP + 4
            END-PERFORM
            DISPLAY WS-PRT (1:WS-LS)

            INITIALIZE WS-PRT
            COMPUTE WS-PP = 1
            PERFORM VARYING WS-COL FROM 1 BY +1
            UNTIL WS-COL > 3
            COMPUTE WS-MM = 3 * (WS-QQ - 1) + WS-COL

              IF WS-COL = 1
                COMPUTE WS-PP = WS-PP + WS-LMAR + 2 - WS-DNMW
              ELSE
                COMPUTE WS-PP = WS-PP + WS-SPBC + 2 - WS-DNMW
              END-IF
              PERFORM VARYING WS-DD FROM 1 BY +1
              UNTIL WS-DD > 7
                IF WS-DD > 1
                  COMPUTE WS-PP = WS-PP + WS-SPBD + 2 - WS-DNMW
                END-IF
                MOVE WS-DAY-NAME (WS-DD) (1:WS-DNMW)
                            TO WS-PRT (WS-PP:WS-DNMW)
                COMPUTE WS-PP = WS-PP + WS-DNMW
              END-PERFORM
            END-PERFORM
            DISPLAY WS-PRT (1:WS-LS)

            PERFORM VARYING WS-WK FROM 1 BY +1
            UNTIL WS-WK > 6
              INITIALIZE WS-PRT
              COMPUTE WS-PP = 1
              PERFORM VARYING WS-COL FROM 1 BY +1
              UNTIL WS-COL > 3
              COMPUTE WS-MM = 3 * (WS-QQ - 1) + WS-COL

                IF WS-COL = 1
                  COMPUTE WS-PP = WS-PP + WS-LMAR
                ELSE
                  COMPUTE WS-PP = WS-PP + WS-SPBC
                END-IF
                PERFORM VARYING WS-DD FROM 1 BY +1
                UNTIL WS-DD > 7
                  IF WS-DD > 1
                    COMPUTE WS-PP = WS-PP + WS-SPBD
                  END-IF
                  MOVE WS-DAY (WS-MM, WS-WK, WS-DD)
                              TO WS-PRT (WS-PP:2)
                  COMPUTE WS-PP = WS-PP + 2
                END-PERFORM
              END-PERFORM
              DISPLAY WS-PRT (1:WS-LS)
            END-PERFORM
            DISPLAY ' '
          END-PERFORM
          GOBACK
          .
      END PROGRAM CALEND.
      IDENTIFICATION DIVISION.
      PROGRAM-ID.  DATE2DOW.
      ENVIRONMENT DIVISION.
      DATA DIVISION.
      WORKING-STORAGE SECTION.
      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(04).
      LINKAGE SECTION.
      01  INPDATE-RECORD.
          05  INPD-YEAR          PIC 9(04).
          05  FILLER             PIC X(01).
          05  INPD-MONTH         PIC 9(02).
          05  FILLER             PIC X(01).
          05  INPD-DAY           PIC 9(02).
      01  WMS-DOW                PIC 9(01).
      PROCEDURE DIVISION USING INPDATE-RECORD, WMS-DOW.
      1010-CONVERT-DATE-TO-DOW.
          IF INPD-MONTH < 3
              COMPUTE WMS-MONTH = INPD-MONTH + 12
              COMPUTE WMS-YEAR  = INPD-YEAR - 1
          ELSE
              COMPUTE WMS-MONTH = INPD-MONTH
              COMPUTE WMS-YEAR  = INPD-YEAR
          END-IF
          COMPUTE WMS-SUM  = 
                           ( INPD-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 WMS-DOW = FUNCTION MOD (WMS-SUM, 7) + 1
          GOBACK
          .
      END PROGRAM DATE2DOW.

</lang> Output (based on 80 character wide display)

     JANUARY         1969     FEBRUARY        1969     MARCH           1969
     SU MO TU WE TH FR SA     SU MO TU WE TH FR SA     SU MO TU WE TH FR SA
               1  2  3  4                        1                        1
      5  6  7  8  9 10 11      2  3  4  5  6  7  8      2  3  4  5  6  7  8
     12 13 14 15 16 17 18      9 10 11 12 13 14 15      9 10 11 12 13 14 15
     19 20 21 22 23 24 25     16 17 18 19 20 21 22     16 17 18 19 20 21 22
     26 27 28 29 30 31        23 24 25 26 27 28        23 24 25 26 27 28 29
                                                       30 31               
                                                                           
     APRIL           1969     MAY             1969     JUNE            1969
     SU MO TU WE TH FR SA     SU MO TU WE TH FR SA     SU MO TU WE TH FR SA
            1  2  3  4  5                  1  2  3      1  2  3  4  5  6  7
      6  7  8  9 10 11 12      4  5  6  7  8  9 10      8  9 10 11 12 13 14
     13 14 15 16 17 18 19     11 12 13 14 15 16 17     15 16 17 18 19 20 21
     20 21 22 23 24 25 26     18 19 20 21 22 23 24     22 23 24 25 26 27 28
     27 28 29 30              25 26 27 28 29 30 31     29 30               
                                                                           
                                                                           
     JULY            1969     AUGUST          1969     SEPTEMBER       1969
     SU MO TU WE TH FR SA     SU MO TU WE TH FR SA     SU MO TU WE TH FR SA
            1  2  3  4  5                     1  2         1  2  3  4  5  6
      6  7  8  9 10 11 12      3  4  5  6  7  8  9      7  8  9 10 11 12 13
     13 14 15 16 17 18 19     10 11 12 13 14 15 16     14 15 16 17 18 19 20
     20 21 22 23 24 25 26     17 18 19 20 21 22 23     21 22 23 24 25 26 27
     27 28 29 30 31           24 25 26 27 28 29 30     28 29 30            
                              31                                           
                                                                           
     OCTOBER         1969     NOVEMBER        1969     DECEMBER        1969
     SU MO TU WE TH FR SA     SU MO TU WE TH FR SA     SU MO TU WE TH FR SA
               1  2  3  4                        1         1  2  3  4  5  6
      5  6  7  8  9 10 11      2  3  4  5  6  7  8      7  8  9 10 11 12 13
     12 13 14 15 16 17 18      9 10 11 12 13 14 15     14 15 16 17 18 19 20
     19 20 21 22 23 24 25     16 17 18 19 20 21 22     21 22 23 24 25 26 27
     26 27 28 29 30 31        23 24 25 26 27 28 29     28 29 30 31         
                              30                                           

D

<lang d>import std.stdio, std.datetime, std.string, std.conv;

void printCalendar(in uint year, in uint nCols) in {

   assert(nCols > 0 && nCols <= 12);

} body {

   immutable rows = 12 / nCols + (12 % nCols != 0);
   auto date = Date(year, 1, 1);
   auto offs = cast(int)date.dayOfWeek;
   const months = "January February March April May June
       July August September October November December".split;
   string[8][12] mons;
   foreach (immutable m; 0 .. 12) {
       mons[m][0] = months[m].center(21);
       mons[m][1] = " Su Mo Tu We Th Fr Sa";
       immutable dim = date.daysInMonth;
       foreach (immutable d; 1 .. 43) {
           immutable day = d > offs && d <= offs + dim;
           immutable str = day ? format(" %2s", d-offs) : "   ";
           mons[m][2 + (d - 1) / 7] ~= str;
       }
       offs = (offs + dim) % 7;
       date.add!"months"(1);
   }
   "[Snoopy Picture]".center(nCols * 24 + 4).writeln;
   writeln(year.text.center(nCols * 24 + 4), "\n");
   foreach (immutable r; 0 .. rows) {
       string[8] s;
       foreach (immutable c; 0 .. nCols) {
           if (r * nCols + c > 11)
               break;
           foreach (immutable i, line; mons[r * nCols + c])
               s[i] ~= format("   %s", line);
       }
       writefln("%-(%s\n%)\n", s);
   }

}

void main() {

   printCalendar(1969, 3);

}</lang>

                              [Snoopy Picture]
                                    1969

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

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


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

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

Icon and Unicon

The procedures printCalendar handles formatting of large components and uses co-expressions to keep the formatting of week elements in each column synchronized. The procedure CalendarFormatWeek is a generator that returns heading elements, alignment spacing, and individual days. <lang Icon>procedure main(A) printCalendar(\A[1]|1969) end

procedure printCalendar(year) #: Print a 3 column x 80 char calendar

  cols := 3                                        # fixed width 
  mons := []                                       # table of months
  "January February March April May June " || 
  "July August September October November December " ?
         while put(mons, tab(find(" "))) do move(1)    
  write(center("[Snoopy Picture]",cols * 24 + 4))  # mandatory ..
  write(center(year,cols * 24 + 4), "\n")          # ... headers
  
  M := list(cols)	                               # coexpr container               
  every  mon := 0 to 9 by cols do {                # go through months by cols
     writes("    ")
     every i := 1 to cols do {
        writes(center(mons[mon+i],24))             # header months
        M[i] := create CalendarFormatWeek(1969,mon + i)  # formatting coexpr 
        }
     write()
     every 1 to 7 do {                             # 1 to max rows                   
        every c := 1 to cols do {                  # for each column
           writes("    ")
           every 1 to 7 do writes(right(@M[c],3))  # each row day element 
           }
        write()
        }
     }

end

link datetime

procedure CalendarFormatWeek(year,m) #: Format Week for Calendar static D initial D := [31,28,31,30,31,30,31,31,30,31,30,31]

every suspend "Su"|"Mo"|"Tu"|"We"|"Th"|"Fr"|"Sa" # header every 1 to (d := (julian(m,1,year)+1)%7) do suspend "" # lead day alignment every suspend 1 to D[m] do d +:= 1 # days if m = 2 & IsLeapYear(year) then suspend (d +:= 1, 29) # LY adjustment every d to (6*7) do suspend "" # trailer alignment end</lang>

datetime.icn provides julian and IsLeapYear

Output:

                              [Snoopy Picture]
                                    1969

            January                 February                 March
     Su Mo Tu We Th Fr Sa     Su Mo Tu We Th Fr Sa     Su Mo Tu We Th Fr Sa
               1  2  3  4                        1                        1
      5  6  7  8  9 10 11      2  3  4  5  6  7  8      2  3  4  5  6  7  8
     12 13 14 15 16 17 18      9 10 11 12 13 14 15      9 10 11 12 13 14 15
     19 20 21 22 23 24 25     16 17 18 19 20 21 22     16 17 18 19 20 21 22
     26 27 28 29 30 31        23 24 25 26 27 28        23 24 25 26 27 28 29
                                                       30 31
             April                    May                     June
     Su Mo Tu We Th Fr Sa     Su Mo Tu We Th Fr Sa     Su Mo Tu We Th Fr Sa
            1  2  3  4  5                  1  2  3      1  2  3  4  5  6  7
      6  7  8  9 10 11 12      4  5  6  7  8  9 10      8  9 10 11 12 13 14
     13 14 15 16 17 18 19     11 12 13 14 15 16 17     15 16 17 18 19 20 21
     20 21 22 23 24 25 26     18 19 20 21 22 23 24     22 23 24 25 26 27 28
     27 28 29 30              25 26 27 28 29 30 31     29 30

              July                   August                September
     Su Mo Tu We Th Fr Sa     Su Mo Tu We Th Fr Sa     Su Mo Tu We Th Fr Sa
            1  2  3  4  5                     1  2         1  2  3  4  5  6
      6  7  8  9 10 11 12      3  4  5  6  7  8  9      7  8  9 10 11 12 13
     13 14 15 16 17 18 19     10 11 12 13 14 15 16     14 15 16 17 18 19 20
     20 21 22 23 24 25 26     17 18 19 20 21 22 23     21 22 23 24 25 26 27
     27 28 29 30 31           24 25 26 27 28 29 30     28 29 30
                              31
            October                 November                December
     Su Mo Tu We Th Fr Sa     Su Mo Tu We Th Fr Sa     Su Mo Tu We Th Fr Sa
               1  2  3  4                        1         1  2  3  4  5  6
      5  6  7  8  9 10 11      2  3  4  5  6  7  8      7  8  9 10 11 12 13
     12 13 14 15 16 17 18      9 10 11 12 13 14 15     14 15 16 17 18 19 20
     19 20 21 22 23 24 25     16 17 18 19 20 21 22     21 22 23 24 25 26 27
     26 27 28 29 30 31        23 24 25 26 27 28 29     28 29 30 31
                              30

J

Solution: <lang j>require 'dates format' NB. J6.x require 'dates general/misc/format' NB. J7.x calBody=: (1 1 }. _1 _1 }. ":)@(-@(<.@%&22)@[ ]\ calendar@]) calTitle=: (<: - 22&|)@[ center '[Insert Snoopy here]' , ,:~ ":@] formatCalendar=: calTitle , calBody</lang> Example use: <lang j> 80 formatCalendar 1969

                     [Insert Snoopy here]                       
                             1969                               
                                                                
        Jan         │         Feb         │         Mar         
Su Mo Tu We Th Fr Sa│ Su Mo Tu We Th Fr Sa│ Su Mo Tu We Th Fr Sa
          1  2  3  4│                    1│                    1
 5  6  7  8  9 10 11│  2  3  4  5  6  7  8│  2  3  4  5  6  7  8
12 13 14 15 16 17 18│  9 10 11 12 13 14 15│  9 10 11 12 13 14 15
19 20 21 22 23 24 25│ 16 17 18 19 20 21 22│ 16 17 18 19 20 21 22
26 27 28 29 30 31   │ 23 24 25 26 27 28   │ 23 24 25 26 27 28 29
                    │                     │ 30 31               

─────────────────────┼─────────────────────┼─────────────────────

        Apr         │         May         │         Jun         
Su Mo Tu We Th Fr Sa│ Su Mo Tu We Th Fr Sa│ Su Mo Tu We Th Fr Sa
       1  2  3  4  5│              1  2  3│  1  2  3  4  5  6  7
 6  7  8  9 10 11 12│  4  5  6  7  8  9 10│  8  9 10 11 12 13 14
13 14 15 16 17 18 19│ 11 12 13 14 15 16 17│ 15 16 17 18 19 20 21
20 21 22 23 24 25 26│ 18 19 20 21 22 23 24│ 22 23 24 25 26 27 28
27 28 29 30         │ 25 26 27 28 29 30 31│ 29 30               
                    │                     │                     

─────────────────────┼─────────────────────┼─────────────────────

        Jul         │         Aug         │         Sep         
Su Mo Tu We Th Fr Sa│ Su Mo Tu We Th Fr Sa│ Su Mo Tu We Th Fr Sa
       1  2  3  4  5│                 1  2│     1  2  3  4  5  6
 6  7  8  9 10 11 12│  3  4  5  6  7  8  9│  7  8  9 10 11 12 13
13 14 15 16 17 18 19│ 10 11 12 13 14 15 16│ 14 15 16 17 18 19 20
20 21 22 23 24 25 26│ 17 18 19 20 21 22 23│ 21 22 23 24 25 26 27
27 28 29 30 31      │ 24 25 26 27 28 29 30│ 28 29 30            
                    │ 31                  │                     

─────────────────────┼─────────────────────┼─────────────────────

        Oct         │         Nov         │         Dec         
Su Mo Tu We Th Fr Sa│ Su Mo Tu We Th Fr Sa│ Su Mo Tu We Th Fr Sa
          1  2  3  4│                    1│     1  2  3  4  5  6
 5  6  7  8  9 10 11│  2  3  4  5  6  7  8│  7  8  9 10 11 12 13
12 13 14 15 16 17 18│  9 10 11 12 13 14 15│ 14 15 16 17 18 19 20
19 20 21 22 23 24 25│ 16 17 18 19 20 21 22│ 21 22 23 24 25 26 27
26 27 28 29 30 31   │ 23 24 25 26 27 28 29│ 28 29 30 31         
                    │ 30                  │                     </lang>


Mathematica

Calendar is set of routines for handling calendars; It is built into Mathematica. We're only going to use it for a two functions, namely, DayOfWeek and DaysBetween.

<lang Mathematica> Needs["Calendar`"]; </lang>

Monthly calendar takes a year and a month and returns a simply formatted calendar for that month. It knows about leap years.

<lang Mathematica> monthlyCalendar[y_, m_] :=

   Module[{
          days = {Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday}, 
          months = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"}, 
          d1, shortDays, offset, daysInMonth},
    d1 = DayOfWeek[{y, m, 1}];
    daysInMonth[year_, month_] := DaysBetween[{year, month, 1}, {If[month == 12, year + 1, year],  If[month == 12, 1, month + 1], 1}];
    shortDays = (StringTake[ToString[#], 3] & /@ days);
    offset = d1 /. Thread[days -> Range[0, 6]];
    Grid[
            Prepend[
                    Prepend[
                            Partition[
                                  PadRight[PadLeft[Range[daysInMonth[y, m]], daysInMonth[y, m] + offset, ""], 
                                                 36, ""  ], 
                                          7], 
                                  shortDays],
                                   {monthsm, SpanFromLeft}]]]

</lang>

yearlyCalendar prints out calendars for each of the 12 months in the year.

<lang Mathematica>

  yearlyCalendar[y_] := Grid[Partition[Table[monthlyCalendar[y, k], {k, 12}], 3], Spacings -> {4, 2}];

</lang>

Perl

#!/usr/bin/perl
use strict;
use warnings;
use Time::Local;

my @names = qw/ JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC/;

my $year = shift ||'2007';

for my $month (0..11) {
    print " $names[$month] $year\n";
    print calendar($year, $month), "\n\n";
}

sub calendar {
    my ($year, $month) = @_;
    my @mon_days = qw/31 28 31 30 31 30 31 31 30 31 30 31/;
    ++$mon_days[1] if $year % 4 == 0 && ($year % 400 == 0 || $year % 1
+00 != 0);
    
    my $cal = " Sun Mon Tue Wed Thu Fri Sat\n";

    # Months are indexed beginning at 0
    my $time = timegm(0,0,0,1,$month,$year);
    my $wday = (gmtime $time)[6];
    
    $cal .= "    " x $wday;
    
    my $mday = 1;

    while ($mday <= $mon_days[$month]) {
        $cal .= sprintf "%4s", $mday++;
        $cal .= "\n" if ($wday + $mday -1) % 7 == 0;
    }
    return $cal;
}
# Let's use this as a placeholder until a better solution arrives, OK?

Perl 6

<lang perl6>my $months-per-col = 3; my @week-day-names = <Mo Tu We Th Fr Sa Su>; my @month-names = <Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec>;

my Int $year = +(@*ARGS.shift || 1969);

say fmt-year($year); exit;

sub fmt-year ($year) {

       my $str = (' ' x 30) ~ $year ~ "\n";
       my @month-strs;
       @month-strs[$_] = fmt-month($year, $_).lines for 1 .. 12;
       loop ( my $month = 1; $month <= 12; $month += $months-per-col ) {
               while @month-strs[$month] {
                       for ^$months-per-col {
                               next unless @month-strs[$month+$_];
                               $str ~= @month-strs[$month+$_].shift;
                               $str ~= " " x 3;
                       }
                       $str ~= "\n";
               }
               $str ~= "\n";
       }
       return $str;

} sub fmt-month ($year, $month) {

       my $str = sprintf "%-20s\n", @month-names[$month-1];
       $str ~= @week-day-names~"\n";
       my $date = DateTime.new(year => $year, month => $month);
       my $week-day = $date.day-of-week;
       $str ~= ("  " xx $week-day-1).join(" ");
       for $date.day .. $date.days-in-month -> $day {
               $date = DateTime.new(year => $year, month => $month, day => $day);
               $str ~= " " if 1 < $week-day < 8;
               if $week-day == 8 {
                       $str ~= "\n";
                       $week-day = 1;
               }
               $str ~= sprintf "%2d", $day;
               $week-day++;
       }
       $str ~= " " if $week-day < 8;
       $str ~= ("  " xx 8-$week-day).join(" ");
       $str ~= "\n";
       return $str;

} </lang>

PicoLisp

This "calendar" is nicely formatted, and fits into 20 columns ;-) <lang PicoLisp>(de cal (Year)

  (prinl "====== " Year " ======")
  (for Dat (range (date Year 1 1) (date Year 12 31))
     (let D (date Dat)
        (tab (3 3 4 8)
           (when (= 1 (caddr D))
              (get *Mon (cadr D)) )
           (caddr D)
           (day Dat *Day)
           (when (=0 (% (inc Dat) 7))
              (pack "Week " (week Dat)) ) ) ) ) )

(cal 1969)</lang> Output:

====== 1969 ======
Jan  1 Wed        
     2 Thu        
     3 Fri        
     4 Sat        
     5 Sun        
     6 Mon  Week 2
     7 Tue        
....
    28 Sat        
    29 Sun        
    30 Mon Week 27
Jul  1 Tue        
     2 Wed        
     3 Thu        
     4 Fri        
....
    25 Thu        
    26 Fri        
    27 Sat        
    28 Sun        
    29 Mon Week 53
    30 Tue        
    31 Wed

Pike

the Calendar in Pike does not handle the transitions from the Julian to the Gregorian calendar, but it handles those separately. the default calendar is ISO, other options are Gregorian, Julian, Bahai, Coptic, Islamic and Discordian.

this script also highlights holidays by region. regions may be chosen by 2-letter country name, as well as some special 'regions': christianity, orthodox, bahai, islamic, among others.

<lang Pike>#!/bin/env pike

int main(int argc, array(string) argv) {

   object cal = Calendar;
   object year;
   string region = "us";
   array date = argv[1..];
   if (sizeof(date) && objectp(Calendar[date[0]]) && Calendar[date[0]]->Day)
   {
       cal = Calendar[date[0]];
       date = Array.shift(date)[1];
   }
   if (sizeof(date) && (int)date[0])
   {
       year = cal.Year((int)date[0]);
       date = Array.shift(date)[1];
   }
   if (sizeof(date))
       region = date[0];
   if (!year)
       year = cal.Year();
   print_year(year, region);

}

array make_month(object month, int field_width, void|string region) {

   array out =({});
   mapping holidays = ([]);
   object today = Calendar.Day();
   if (region)
       holidays = Calendar.Events.find_region(region)->scan_events(month);
   array weekday_names = sprintf("%*.*s", field_width, field_width, month->week()->days()->week_day_shortname()[*]);
   out += ({ ({ month->month_name(), month->month_no(), month->year_name() }) });
   out += ({ weekday_names });
   out += showday(month->weeks()->days()[*][*], month, today, holidays, field_width);  
   out += ({ ({ " "*field_width })*sizeof(weekday_names) });
   return out;

}

string print_month(object _month, void|int field_width, void|string region) {

   if (!field_width)
       field_width = 2;
   array month = make_month(_month, field_width, region);
   string out = "";
   out += sprintf("%|*s\n", (field_width+1)*sizeof(month[1])-1, sprintf("%s", month[0][0])); 
   out += sprintf((month[1..][*]*" ")*"\n");
   return out;

}

string print_year(object year, void|string region) {

       array output = ({});
       int day_width = 2;
       int columns = Stdio.stdout.tcgetattr()->columns;
       int month_width = sizeof(make_month(year->month(), day_width)[1]) * (day_width+1) - 1;
       if (columns < month_width)
           columns = month_width;
       // try to find an optimal good looking solution to spread the months
       // across the terminal width
       // for the common calendar of 12 months this is easy but we need to
       // account for caledars that have more than 12 months
       float max_width = (float)((columns+2)/(month_width+2));
       float max_height = ceil(year->number_of_months()/max_width);
       float w = max_width;
       
       while(ceil(year->number_of_months()/(w-1)) == max_height)
           w--;
       
       foreach(print_month(year->months()[*], day_width, region)/w;; array row)
       {
           array rows = row[*]/"\n";
           int l = max(@sizeof(rows[*]));
           foreach(rows; int i;)
           {
               // the last line of each month is an empty line.
               // repeat the line as many times as needed to make the months equally long
               rows[i]+=({ rows[i][-1] })*(l-sizeof(rows[i]));
           }
           rows = Array.transpose(rows);
           output += rows[*]*"  ";
       }
       write("%*|s\n", sizeof(output[1]), year->format_nice());
       write(output * "\n");
       write("\n");

}

string showday(object day, object month, object today, mapping holidays, int field_width) {

   string dayname;
   if (day->month() == month)
   {
       dayname = (string)day->month_day();
       dayname = " "*(sizeof((string)month->number_of_days())-sizeof(dayname))+dayname;
       if (day == today)
           dayname = sprintf("%|*.*s", field_width, field_width, dayname);
       else
           dayname = sprintf("%|*.*s", field_width, field_width, dayname);
       if (holidays[day])
           dayname = sprintf("%|s", dayname);
   }
   else
       dayname = " "*field_width;
   return dayname;

} </lang> Output: (holidays lost in copy-paste)

                               1969                              
       January               February               March        
 Mo Tu We Th Fr Sa Su  Mo Tu We Th Fr Sa Su  Mo Tu We Th Fr Sa Su
        1  2  3  4  5                  1  2                  1  2
  6  7  8  9 10 11 12   3  4  5  6  7  8  9   3  4  5  6  7  8  9
 13 14 15 16 17 18 19  10 11 12 13 14 15 16  10 11 12 13 14 15 16
 20 21 22 23 24 25 26  17 18 19 20 21 22 23  17 18 19 20 21 22 23
 27 28 29 30 31        24 25 26 27 28        24 25 26 27 28 29 30
                                             31                  
                                                                 
        April                  May                   June        
 Mo Tu We Th Fr Sa Su  Mo Tu We Th Fr Sa Su  Mo Tu We Th Fr Sa Su
     1  2  3  4  5  6            1  2  3  4                     1
  7  8  9 10 11 12 13   5  6  7  8  9 10 11   2  3  4  5  6  7  8
 14 15 16 17 18 19 20  12 13 14 15 16 17 18   9 10 11 12 13 14 15
 21 22 23 24 25 26 27  19 20 21 22 23 24 25  16 17 18 19 20 21 22
 28 29 30              26 27 28 29 30 31     23 24 25 26 27 28 29
                                             30                  
                                                                 
         July                 August              September      
 Mo Tu We Th Fr Sa Su  Mo Tu We Th Fr Sa Su  Mo Tu We Th Fr Sa Su
     1  2  3  4  5  6               1  2  3   1  2  3  4  5  6  7
  7  8  9 10 11 12 13   4  5  6  7  8  9 10   8  9 10 11 12 13 14
 14 15 16 17 18 19 20  11 12 13 14 15 16 17  15 16 17 18 19 20 21
 21 22 23 24 25 26 27  18 19 20 21 22 23 24  22 23 24 25 26 27 28
 28 29 30 31           25 26 27 28 29 30 31  29 30               
                                                                 
       October               November              December      
 Mo Tu We Th Fr Sa Su  Mo Tu We Th Fr Sa Su  Mo Tu We Th Fr Sa Su
        1  2  3  4  5                  1  2   1  2  3  4  5  6  7
  6  7  8  9 10 11 12   3  4  5  6  7  8  9   8  9 10 11 12 13 14
 13 14 15 16 17 18 19  10 11 12 13 14 15 16  15 16 17 18 19 20 21
 20 21 22 23 24 25 26  17 18 19 20 21 22 23  22 23 24 25 26 27 28
 27 28 29 30 31        24 25 26 27 28 29 30  29 30 31

PL/I

<lang PL/I> calendar: procedure (year) options (main);

  declare year character (4) varying;
  declare (a, b, c) (0:5,0:6) character (3);
  declare name_month(12) static character (9) varying initial (
     'JANUARY', 'FEBRUARY', 'MARCH',     'APRIL',   'MAY',      'JUNE',
     'JULY',    'AUGUST',   'SEPTEMBER', 'OCTOBER', 'NOVEMBER', 'DECEMBER'); 
  declare i fixed;
  declare (mm, mmp1, mmp2) pic '99';
  put edit (center('CALENDAR FOR ' || YEAR, 67)) (a);
  put skip (2);
  do mm = 1 to 12 by 3;
     mmp1 = mm + 1; mmp2 = mm + 2;
     call prepare_month('01' || mm   || YEAR, a);
     call prepare_month('01' || mmp1 || YEAR, b);
     call prepare_month('01' || mmp2 || YEAR, c);
     put skip edit (center(name_month(mm),   23),
                    center(name_month(mmp1), 23),
                    center(name_month(mmp2), 23) ) (a);
     put skip edit ((3)'  M  T  W  T  F  S  S  ') (a);
     do i = 0 to 5;
        put skip edit (a(i,*), b(i,*), c(i,*)) (7 a, x(2));
     end;
  end;

prepare_month: procedure (start, month);

  declare month(0:5,0:6) character (3);
  declare start character (8);
  declare i pic 'ZZ9';
  declare offset fixed;
  declare (j, day) fixed binary (31);
  declare (this_month, next_month, k) fixed binary;
  day = days(start, 'DDMMYYYY');
  offset = weekday(day) - 1;
  if offset  = 0 then offset = 7;
  month = ;
  do j = day by 1;
     this_month = substr(daystodate(j,   'DDMMYYYY'), 3, 2);
     next_month = substr(daystodate(j+1, 'DDMMYYYY'), 3, 2);
     if this_month^= next_month then leave;
  end;
  i = 1;
  do k = offset-1 to offset+j-day-1;
     month(k/7, mod(k,7)) = i; i = i + 1;
  end;

end prepare_month;

end calendar; </lang> Output:

                         CALENDAR FOR 1969                         


        JANUARY               FEBRUARY                 MARCH         
  M  T  W  T  F  S  S    M  T  W  T  F  S  S    M  T  W  T  F  S  S  
        1  2  3  4  5                   1  2                   1  2
  6  7  8  9 10 11 12    3  4  5  6  7  8  9    3  4  5  6  7  8  9
 13 14 15 16 17 18 19   10 11 12 13 14 15 16   10 11 12 13 14 15 16
 20 21 22 23 24 25 26   17 18 19 20 21 22 23   17 18 19 20 21 22 23
 27 28 29 30 31         24 25 26 27 28         24 25 26 27 28 29 30
                                               31                  
         APRIL                   MAY                   JUNE          
  M  T  W  T  F  S  S    M  T  W  T  F  S  S    M  T  W  T  F  S  S  
     1  2  3  4  5  6             1  2  3  4                      1
  7  8  9 10 11 12 13    5  6  7  8  9 10 11    2  3  4  5  6  7  8
 14 15 16 17 18 19 20   12 13 14 15 16 17 18    9 10 11 12 13 14 15
 21 22 23 24 25 26 27   19 20 21 22 23 24 25   16 17 18 19 20 21 22
 28 29 30               26 27 28 29 30 31      23 24 25 26 27 28 29
                                               30                  
         JULY                  AUGUST                SEPTEMBER       
  M  T  W  T  F  S  S    M  T  W  T  F  S  S    M  T  W  T  F  S  S  
     1  2  3  4  5  6                1  2  3    1  2  3  4  5  6  7
  7  8  9 10 11 12 13    4  5  6  7  8  9 10    8  9 10 11 12 13 14
 14 15 16 17 18 19 20   11 12 13 14 15 16 17   15 16 17 18 19 20 21
 21 22 23 24 25 26 27   18 19 20 21 22 23 24   22 23 24 25 26 27 28
 28 29 30 31            25 26 27 28 29 30 31   29 30               
                                                                   
        OCTOBER               NOVEMBER               DECEMBER        
  M  T  W  T  F  S  S    M  T  W  T  F  S  S    M  T  W  T  F  S  S  
        1  2  3  4  5                   1  2    1  2  3  4  5  6  7
  6  7  8  9 10 11 12    3  4  5  6  7  8  9    8  9 10 11 12 13 14
 13 14 15 16 17 18 19   10 11 12 13 14 15 16   15 16 17 18 19 20 21
 20 21 22 23 24 25 26   17 18 19 20 21 22 23   22 23 24 25 26 27 28
 27 28 29 30 31         24 25 26 27 28 29 30   29 30 31            

Extract for 2013:

                         CALENDAR FOR 2013                         


        JANUARY               FEBRUARY                 MARCH         
  M  T  W  T  F  S  S    M  T  W  T  F  S  S    M  T  W  T  F  S  S  
     1  2  3  4  5  6                1  2  3                1  2  3
  7  8  9 10 11 12 13    4  5  6  7  8  9 10    4  5  6  7  8  9 10
 14 15 16 17 18 19 20   11 12 13 14 15 16 17   11 12 13 14 15 16 17
 21 22 23 24 25 26 27   18 19 20 21 22 23 24   18 19 20 21 22 23 24
 28 29 30 31            25 26 27 28            25 26 27 28 29 30 31

Python

The Python calendar.pryear function prints calendars with the following formatting options: optional parameters w, l, and c are for date column width, lines per week, and number of spaces between month columns, respectively.

Although rumoured to be getting an anti-gravity module, Python as yet does not include a snoopy module ;-) <lang python>>>> import calendar >>> help(calendar.prcal) Help on method pryear in module calendar:

pryear(self, theyear, w=0, l=0, c=6, m=3) method of calendar.TextCalendar instance

   Print a years calendar.

>>> calendar.prcal(1969)

                                 1969
     January                   February                   March

Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su

      1  2  3  4  5                      1  2                      1  2
6  7  8  9 10 11 12       3  4  5  6  7  8  9       3  4  5  6  7  8  9

13 14 15 16 17 18 19 10 11 12 13 14 15 16 10 11 12 13 14 15 16 20 21 22 23 24 25 26 17 18 19 20 21 22 23 17 18 19 20 21 22 23 27 28 29 30 31 24 25 26 27 28 24 25 26 27 28 29 30

                                                   31
      April                      May                       June

Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su

   1  2  3  4  5  6                1  2  3  4                         1
7  8  9 10 11 12 13       5  6  7  8  9 10 11       2  3  4  5  6  7  8

14 15 16 17 18 19 20 12 13 14 15 16 17 18 9 10 11 12 13 14 15 21 22 23 24 25 26 27 19 20 21 22 23 24 25 16 17 18 19 20 21 22 28 29 30 26 27 28 29 30 31 23 24 25 26 27 28 29

                                                   30
       July                     August                  September

Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su

   1  2  3  4  5  6                   1  2  3       1  2  3  4  5  6  7
7  8  9 10 11 12 13       4  5  6  7  8  9 10       8  9 10 11 12 13 14

14 15 16 17 18 19 20 11 12 13 14 15 16 17 15 16 17 18 19 20 21 21 22 23 24 25 26 27 18 19 20 21 22 23 24 22 23 24 25 26 27 28 28 29 30 31 25 26 27 28 29 30 31 29 30

     October                   November                  December

Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su

      1  2  3  4  5                      1  2       1  2  3  4  5  6  7
6  7  8  9 10 11 12       3  4  5  6  7  8  9       8  9 10 11 12 13 14

13 14 15 16 17 18 19 10 11 12 13 14 15 16 15 16 17 18 19 20 21 20 21 22 23 24 25 26 17 18 19 20 21 22 23 22 23 24 25 26 27 28 27 28 29 30 31 24 25 26 27 28 29 30 29 30 31

>>> print('1234567890'*8) 12345678901234567890123456789012345678901234567890123456789012345678901234567890 >>> </lang>

Racket

<lang racket>

  1. lang racket

(require racket/date) (define (calendar yr)

 (define (nsplit n l) (if (null? l) l (cons (take l n) (nsplit n (drop l n)))))
 (define months
   (for/list ([mn (in-naturals 1)]
              [mname '(January February March April May June July
                       August September October November December)])
     (define s (find-seconds 0 0 12 1 mn yr))
     (define pfx (date-week-day (seconds->date s)))
     (define days
       (let ([? (if (= mn 12) (λ(x y) y) (λ(x y) x))])
         (round (/ (- (find-seconds 0 0 12 1 (? (+ 1 mn) 1) (? yr (+ 1 yr))) s)
                   60 60 24))))
     (list* (~a mname #:width 20 #:align 'center) "Su Mo Tu We Th Fr Sa"
            (map string-join
                 (nsplit 7 `(,@(make-list pfx "  ")
                             ,@(for/list ([d days])
                                 (~a (+ d 1) #:width 2 #:align 'right))
                             ,@(make-list (- 42 pfx days) "  ")))))))
 (let* ([s '(" 11,-~4-._3. 41-4! 10/ ()=(2) 3\\ 40~a! 9( 3( 80 39-4! 10\\._\\"
             ", ,-4'! 5#2X3x7! 12/ 2-3'~2;! 11/ 4/~2|-! 9=( 3~4 2|! 3/~42\\! "
             "2/_23\\! /_25\\!/_27\\! 3|_20|! 3|_20|! 3|_20|! 3| 20|!!")]
        [s (regexp-replace* #rx"!" (string-append* s) "\n")]
        [s (regexp-replace* #rx".(?:[1-7][0-9]*|[1-9])" s
             (λ(m) (make-string (string->number (substring m 1))
                                (string-ref m 0))))])
   (printf s yr))
 (for-each displayln
   (dropf-right (for*/list ([3ms (nsplit 3 months)] [s (apply map list 3ms)])
                  (regexp-replace #rx" +$" (string-join s "   ") ""))
                (λ(s) (equal? "" s)))))

(calendar 1969) </lang>

REXX

Rather than build a program from scratch, I took my generalized REXX program that generated (as an
option) any calendar for any month, and by extension, any number of months (so that an entire
year could be displayed/written).   To make the program much smaller, a LOT of code was removed
(but it's still a sledgehammer doing the work of a small hammer).

Some of the code removed:

  • almost all error checking and the issuing of error messages.
  • the option of using "simple" characters as opposed to a true grid (of ASCII extended characters).
  • the option of highlighting of today's date.
  • the option of using colors.
  • the specifying of what language to use (over 90 languages, default is English).
  • the option of using indentation.
  • the option of using different date formats (to specify the date).
  • the option of using a time addition/subtraction for the date (* -4score-7years).
  • the option of showing the phases of the moon.
  • the option of showing the day-of-the-year (as on financial calendars and others).
  • the option of specifying a calendar fill character (those empty cells in a monthly calender).
  • the option of drawing Snoopy (three versions) and also many other animals/ASCII art.
  • the specifing of alternate outputs (a file/printer/XEDIT/stack/GLOBALVs/etc).
  • the option of displaying the year in blocked form (at the top of the calendar):
                   11          9999999       6666666       9999999
                  111         999999999     666666666     999999999
                 1111        99      99    66      66    99      99
                   11        99      99    66            99      99
                   11        99     999    66            99     999
                   11         999999999    66 666666      999999999
                   11          99999 99    6666666666      99999 99
                   11                99    666     66            99
                   11                99    66      66            99
                   11        99      99    66      66    99      99
                 111111       99999999      66666666      99999999
                 111111        999999        666666        999999


Most of the code is dealing with drawing a cell (grid) for each day-of-the-month, so the program
is a bit more complex than it has to be for this task.   Also, it was designed for any year, any
month(s), and any size screen/device to show (display) it.   Accommodations were made in the program
to allow the choice of what type of cells would be generated: small/smaller/smallest for height, and
narrow/narrower/narrowest for the width.   The size (width/depth) of the output device/terminal can be
specified.   The choice could've been performed programmatically, but I never believe that a program
could best choose over what the user wants, as it depends on esthetics and looks (fashion). <lang rexx>/*REXX program to show any year's (monthly) calendar (with/without grid)*/

@abc='abcdefghijklmnopqrstuvwxyz'; @abcU=@abc; upper @abcU calfill=' '; mc=12; _='1 3 1234567890' "fb"x parse var _ grid calspaces # chk . cv_ days.1 days.2 days.3 daysn sd sw _=0; parse var _ cols 1 jd 1 lowerCase 1 maxKalPuts 1 narrow 1,

                narrower 1 narrowest 1 short 1 shorter 1 shortest 1,
                small 1 smaller 1 smallest 1 upperCase

parse arg mm '/' dd "/" yyyy _ '(' ops; uops=ops if _\== | \is#(mm) | \is#(dd) | \is#(yyyy) then call erx 86

 do while ops\==; ops=strip(ops,'L'); parse var ops _1 2 1 _ . 1 _o ops
 upper _
      select
      when  abb('CALSPaces')  then calspaces=nai()
      when  abb('DEPth')      then        sd=nai()
      when abbn('GRIDs')      then      grid=no()
      when abbn('LOWercase')  then lowerCase=no()
      when  abb('CALMONths')  then        mc=nai()
      when abbn('NARrow')     then    narrow=no()
      when abbn('NARROWER')   then  narrower=no()
      when abbn('NARROWESt')  then narrowest=no()
      when abbn('SHORt')      then     short=no()
      when abbn('SHORTER')    then   shorter=no()
      when abbn('SHORTESt')   then  shortest=no()
      when abbn('SMALl')      then     small=no()
      when abbn('SMALLER')    then   smaller=no()
      when abbn('SMALLESt')   then  smallest=no()
      when abbn('UPPercase')  then upperCase=no()
      when  abb('WIDth')      then        sw=nai()
      otherwise nop
      end    /*select*/
 end         /*do while opts\== ...*/

mc=int(mc,'monthscalender'); if mc>0 then cal=1 days='Sunday Monday Tuesday Wednesday Thursday Friday Saturday' months='January February March April May June July August September October November December' days=' 'days; months=' 'months cyyyy=right(date(),4); hyy=left(cyyyy,2); lyy=right(cyyyy,2) dy.=31; _=30; parse var _ dy.4 1 dy.6 1 dy.9 1 dy.11; dy.2=28+ly(yyyy) yy=right(yyyy,2); sd=p(sd 43); sw=p(sw 80); cw=10; cindent=1; calwidth=76 if small then do; narrow=1  ; short=1  ; end if smaller then do; narrower=1 ; shorter=1 ; end if smallest then do; narrowest=1; shortest=1; end if shortest then shorter=1 if shorter then short =1 if narrow then do; cw=9; cindent=3; calwidth=69; end if narrower then do; cw=4; cindent=1; calwidth=34; end if narrowest then do; cw=2; cindent=1; calwidth=20; end cv_=calwidth+calspaces+2 calfill=left(copies(calfill,cw),cw)

     do j=1 for 7;         _=word(days,j)
           do jw=1 for 3;  _d=strip(substr(_,cw*jw-cw+1,cw))
           if jw=1 then _d=centre(_d,cw+1)
                   else _d=left(_d,cw+1)
           days.jw=days.jw||_d
           end   /*jw*/
     __=daysn
     if narrower  then daysn=__||centre(left(_,3),5)
     if narrowest then daysn=__||center(left(_,2),3)
     end   /*j*/

_yyyy=yyyy; calPuts=0; cv=1; _mm=mm+0; month=word(months,mm) dy.2=28+ly(_yyyy); dim=dy._mm; _dd=01; dow=dow(_mm,_dd,_yyyy); $dd=dd+0

/*─────────────────────────────now: the business of the building the cal*/ call calGen

              do _j=2 to mc
              if cv_\== then do
                               cv=cv+cv_
                               if cv+cv_>=sw then do; cv=1; call calPut
                                                  call fcalPuts;call calPb
                                                  end
                                             else calPuts=0
                               end
                          else do;call calPb;call calPut;call fcalPuts;end
              _mm=_mm+1;  if _mm==13 then do;  _mm=1; _yyyy=_yyyy+1;  end
              month=word(months,_mm); dy.2=28+ly(_yyyy); dim=dy._mm
              dow=dow(_mm,_dd,_yyyy); $dd=0; call calGen
              end   /*_j*/

call fcalPuts return _

/*─────────────────────────────calGen subroutine────────────────────────*/ calGen: cellX=;cellJ=;cellM=;calCells=0;calline=0 call calPut call calPutl copies('─',calwidth),"┌┐"; call calHd call calPutl month ' ' _yyyy  ; call calHd if narrowest | narrower then call calPutl daysn

                       else do jw=1 for 3
                            if space(days.jw)\== then call calPutl days.jw
                            end

calft=1; calfb=0

 do jf=1 for dow-1; call cellDraw calFill,calFill; end
 do jy=1 for dim; call cellDraw jy; end

calfb=1

 do 7; call cellDraw calFill,calFill; end

if sd>32 & \shorter then call calPut return

/*─────────────────────────────cellDraw subroutine──────────────────────*/ cellDraw: parse arg zz,cdDOY;zz=right(zz,2);calCells=calCells+1 if calCells>7 then do

                  calLine=calLine+1
                  cellX=substr(cellX,2)
                  cellJ=substr(cellJ,2)
                  cellM=substr(cellM,2)
                  cellB=translate(cellX,,")(─-"#)
                  if calLine==1 then call cx
                  call calCsm; call calPutl cellX; call calCsj; call cx
                  cellX=; cellJ=; cellM=; calCells=1
                  end

cdDOY=right(cdDOY,cw); cellM=cellM'│'center(,cw) cellX=cellX'│'centre(zz,cw); cellJ=cellJ'│'center(,cw) return

/*═════════════════════════════general 1-line subs══════════════════════*/ abb:arg abbu;parse arg abb;return abbrev(abbu,_,abbl(abb)) abbl:return verify(arg(1)'a',@abc,'M')-1 abbn:parse arg abbn;return abb(abbn)|abb('NO'abbn) calCsj:if sd>49&\shorter then call calPutl cellB;if sd>24&\short then call calPutl cellJ; return calCsm:if sd>24&\short then call calPutl cellM;if sd>49&\shorter then call calPutl cellB;return calHd:if sd>24&\shorter then call calPutl;if sd>32&\shortest then call calPutl;return calPb:if \grid&shortest then call put chk;return calPut:calPuts=calPuts+1;maxKalPuts=max(maxKalPuts,calPuts);if symbol('CT.'calPuts)\=='VAR' then ct.calPuts=;ct.calPuts=overlay(arg(1),ct.calPuts,cv);return calPutl:call calPut copies(' ',cindent)left(arg(2)"│",1)center(arg(1),calwidth)||right('│'arg(2),1);return cx:cx_='├┤';cx=copies(copies('─',cw)'┼',7);if calft then do;cx=translate(cx,'┬',"┼");calft=0;end;if calfb then do;cx=translate(cx,'┴',"┼");cx_='└┘';calfb=0;end;call calPutl cx,cx_;return dow:procedure;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 er:parse arg _1,_2;call '$ERR' "14"p(_1) p(word(_1,2) !fid(1)) _2;if _1<0 then return _1;exit result err:call er '-'arg(1),arg(2);return erx:call er '-'arg(1),arg(2);exit fcalPuts: do j=1 for maxKalPuts;call put ct.j;end;ct.=;maxKalPuts=0;calPuts=0;return int:int=numx(arg(1),arg(2));if \isint(int) then call erx 92,arg(1) arg(2);return int/1 is#:return verify(arg(1),#)==0 isint:return datatype(arg(1),'W') lower:return translate(arg(1),@abc,@abcU) ly:arg _;if length(_)==2 then _=hyy||_;ly=_//4==0;if ly==0 then return 0;ly=((_//100\==0)|_//400==0);return ly na:if arg(1)\== then call erx 01,arg(2);parse var ops na ops;if na== then call erx 35,_o;return na nai:return int(na(),_o) nan:return numx(na(),_o) no:if arg(1)\== then call erx 01,arg(2);return left(_,2)\=='NO' num:procedure;parse arg x .,f,q;if x== then return x;if datatype(x,'N') then return x/1;x=space(translate(x,,','),0);if datatype(x,'N') then return x/1;return numnot() numnot:if q==1 then return x;if q== then call er 53,x f;call erx 53,x f numx:return num(arg(1),arg(2),1) p:return word(arg(1),1) put:_=arg(1);_=translate(_,,'_'chk);if \grid then _=ungrid(_);if lowerCase then _=lower(_);if upperCase then upper _;if shortest&_=' ' then return;call tell _;return tell:say arg(1);return ungrid:return translate(arg(1),,"│║─═┤┐└┴┬├┼┘┌╔╗╚╝╟╢╞╡╫╪╤╧╥╨╠╣")</lang> output when using the input of: 1/1/1969 (noGrid smallest narrowest)

                          «Snoopy "picture" here» 

     January   1969          February   1969            March   1969
  Su Mo Tu We Th Fr Sa     Su Mo Tu We Th Fr Sa     Su Mo Tu We Th Fr Sa
            1  2  3  4                        1                        1
   5  6  7  8  9 10 11      2  3  4  5  6  7  8      2  3  4  5  6  7  8
  12 13 14 15 16 17 18      9 10 11 12 13 14 15      9 10 11 12 13 14 15
  19 20 21 22 23 24 25     16 17 18 19 20 21 22     16 17 18 19 20 21 22
  26 27 28 29 30 31        23 24 25 26 27 28        23 24 25 26 27 28 29
                                                    30 31

      April   1969              May   1969              June   1969
  Su Mo Tu We Th Fr Sa     Su Mo Tu We Th Fr Sa     Su Mo Tu We Th Fr Sa
         1  2  3  4  5                  1  2  3      1  2  3  4  5  6  7
   6  7  8  9 10 11 12      4  5  6  7  8  9 10      8  9 10 11 12 13 14
  13 14 15 16 17 18 19     11 12 13 14 15 16 17     15 16 17 18 19 20 21
  20 21 22 23 24 25 26     18 19 20 21 22 23 24     22 23 24 25 26 27 28
  27 28 29 30              25 26 27 28 29 30 31     29 30

      July   1969             August   1969           September   1969
  Su Mo Tu We Th Fr Sa     Su Mo Tu We Th Fr Sa     Su Mo Tu We Th Fr Sa
         1  2  3  4  5                     1  2         1  2  3  4  5  6
   6  7  8  9 10 11 12      3  4  5  6  7  8  9      7  8  9 10 11 12 13
  13 14 15 16 17 18 19     10 11 12 13 14 15 16     14 15 16 17 18 19 20
  20 21 22 23 24 25 26     17 18 19 20 21 22 23     21 22 23 24 25 26 27
  27 28 29 30 31           24 25 26 27 28 29 30     28 29 30
                           31

     October   1969          November   1969          December   1969
  Su Mo Tu We Th Fr Sa     Su Mo Tu We Th Fr Sa     Su Mo Tu We Th Fr Sa
            1  2  3  4                        1         1  2  3  4  5  6
   5  6  7  8  9 10 11      2  3  4  5  6  7  8      7  8  9 10 11 12 13
  12 13 14 15 16 17 18      9 10 11 12 13 14 15     14 15 16 17 18 19 20
  19 20 21 22 23 24 25     16 17 18 19 20 21 22     21 22 23 24 25 26 27
  26 27 28 29 30 31        23 24 25 26 27 28 29     28 29 30 31
                           30

Output when using the input of: 1/1/1969 (smallest narrowest width 156 calSpaces 5)
A width of 156 was used to illustrate showing a grid, otherwise it would fit in 132 columns.

 ┌────────────────────┐   ┌────────────────────┐   ┌────────────────────┐   ┌────────────────────┐   ┌────────────────────┐   ┌────────────────────┐
 │   January   1969   │   │  February   1969   │   │    March   1969    │   │    April   1969    │   │     May   1969     │   │    June   1969     │
 │Su Mo Tu We Th Fr Sa│   │Su Mo Tu We Th Fr Sa│   │Su Mo Tu We Th Fr Sa│   │Su Mo Tu We Th Fr Sa│   │Su Mo Tu We Th Fr Sa│   │Su Mo Tu We Th Fr Sa│
 ├──┬──┬──┬──┬──┬──┬──┤   ├──┬──┬──┬──┬──┬──┬──┤   ├──┬──┬──┬──┬──┬──┬──┤   ├──┬──┬──┬──┬──┬──┬──┤   ├──┬──┬──┬──┬──┬──┬──┤   ├──┬──┬──┬──┬──┬──┬──┤
 │  │  │  │ 1│ 2│ 3│ 4│   │  │  │  │  │  │  │ 1│   │  │  │  │  │  │  │ 1│   │  │  │ 1│ 2│ 3│ 4│ 5│   │  │  │  │  │ 1│ 2│ 3│   │ 1│ 2│ 3│ 4│ 5│ 6│ 7│
 ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤
 │ 5│ 6│ 7│ 8│ 9│10│11│   │ 2│ 3│ 4│ 5│ 6│ 7│ 8│   │ 2│ 3│ 4│ 5│ 6│ 7│ 8│   │ 6│ 7│ 8│ 9│10│11│12│   │ 4│ 5│ 6│ 7│ 8│ 9│10│   │ 8│ 9│10│11│12│13│14│
 ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤
 │12│13│14│15│16│17│18│   │ 9│10│11│12│13│14│15│   │ 9│10│11│12│13│14│15│   │13│14│15│16│17│18│19│   │11│12│13│14│15│16│17│   │15│16│17│18│19│20│21│
 ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤
 │19│20│21│22│23│24│25│   │16│17│18│19│20│21│22│   │16│17│18│19│20│21│22│   │20│21│22│23│24│25│26│   │18│19│20│21│22│23│24│   │22│23│24│25│26│27│28│
 ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤
 │26│27│28│29│30│31│  │   │23│24│25│26│27│28│  │   │23│24│25│26│27│28│29│   │27│28│29│30│  │  │  │   │25│26│27│28│29│30│31│   │29│30│  │  │  │  │  │
 └──┴──┴──┴──┴──┴──┴──┘   └──┴──┴──┴──┴──┴──┴──┘   ├──┼──┼──┼──┼──┼──┼──┤   └──┴──┴──┴──┴──┴──┴──┘   └──┴──┴──┴──┴──┴──┴──┘   └──┴──┴──┴──┴──┴──┴──┘
                                                   │30│31│  │  │  │  │  │
                                                   └──┴──┴──┴──┴──┴──┴──┘
 ┌────────────────────┐   ┌────────────────────┐   ┌────────────────────┐   ┌────────────────────┐   ┌────────────────────┐   ┌────────────────────┐
 │    July   1969     │   │   August   1969    │   │  September   1969  │   │   October   1969   │   │  November   1969   │   │  December   1969   │
 │Su Mo Tu We Th Fr Sa│   │Su Mo Tu We Th Fr Sa│   │Su Mo Tu We Th Fr Sa│   │Su Mo Tu We Th Fr Sa│   │Su Mo Tu We Th Fr Sa│   │Su Mo Tu We Th Fr Sa│
 ├──┬──┬──┬──┬──┬──┬──┤   ├──┬──┬──┬──┬──┬──┬──┤   ├──┬──┬──┬──┬──┬──┬──┤   ├──┬──┬──┬──┬──┬──┬──┤   ├──┬──┬──┬──┬──┬──┬──┤   ├──┬──┬──┬──┬──┬──┬──┤
 │  │  │ 1│ 2│ 3│ 4│ 5│   │  │  │  │  │  │ 1│ 2│   │  │ 1│ 2│ 3│ 4│ 5│ 6│   │  │  │  │ 1│ 2│ 3│ 4│   │  │  │  │  │  │  │ 1│   │  │ 1│ 2│ 3│ 4│ 5│ 6│
 ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤
 │ 6│ 7│ 8│ 9│10│11│12│   │ 3│ 4│ 5│ 6│ 7│ 8│ 9│   │ 7│ 8│ 9│10│11│12│13│   │ 5│ 6│ 7│ 8│ 9│10│11│   │ 2│ 3│ 4│ 5│ 6│ 7│ 8│   │ 7│ 8│ 9│10│11│12│13│
 ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤
 │13│14│15│16│17│18│19│   │10│11│12│13│14│15│16│   │14│15│16│17│18│19│20│   │12│13│14│15│16│17│18│   │ 9│10│11│12│13│14│15│   │14│15│16│17│18│19│20│
 ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤
 │20│21│22│23│24│25│26│   │17│18│19│20│21│22│23│   │21│22│23│24│25│26│27│   │19│20│21│22│23│24│25│   │16│17│18│19│20│21│22│   │21│22│23│24│25│26│27│
 ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤   ├──┼──┼──┼──┼──┼──┼──┤
 │27│28│29│30│31│  │  │   │24│25│26│27│28│29│30│   │28│29│30│  │  │  │  │   │26│27│28│29│30│31│  │   │23│24│25│26│27│28│29│   │28│29│30│31│  │  │  │
 └──┴──┴──┴──┴──┴──┴──┘   ├──┼──┼──┼──┼──┼──┼──┤   └──┴──┴──┴──┴──┴──┴──┘   └──┴──┴──┴──┴──┴──┴──┘   ├──┼──┼──┼──┼──┼──┼──┤   └──┴──┴──┴──┴──┴──┴──┘
                          │31│  │  │  │  │  │  │                                                     │30│  │  │  │  │  │  │
                          └──┴──┴──┴──┴──┴──┴──┘                                                     └──┴──┴──┴──┴──┴──┴──┘
                                                                      ,-~~-.___.
                                                                     / ()=(()   \
                                                                    (   (        0
                                                                     \._\, ,----'
                                                                ##XXXxxxxxxx
                                                                       /  ---'~;
                                                                      /    /~|-
                                                                    =(   ~~  |
                                                              /~~~~~~~~~~~~~~~~~~~~~\
                                                             /_______________________\
                                                            /_________________________\
                                                           /___________________________\
                                                              |____________________|
                                                              |____________________|
                                                              |____________________|
                                                              |                    |

Ruby

Date class, from the standard library, knows how many days in a month, and which day is Sunday, for both Julian and Gregorian calendars. This program uses Date class, plus its own assumptions, to create the calendar. This program assumes that every year has 12 months and starts with January 1, and every month fits in 6 weeks starting with Sunday.

  • This program requires Ruby 1.8.7 because it calls Array#each_slice.
Works with: Ruby version 1.8.7

<lang ruby>require 'date'

  1. Creates a calendar of _year_. Returns this calendar as a multi-line
  2. string fit to _columns_.

def cal(year, columns)

 # Start at January 1.
 #
 # Date::ENGLAND marks the switch from Julian calendar to Gregorian
 # calendar at 1752 September 14. This removes September 3 to 13 from
 # year 1752. (By fortune, it keeps January 1.)
 #
 date = Date.new(year, 1, 1, Date::ENGLAND)
 # Collect calendars of all 12 months.
 months = (1..12).collect do |month|
   rows = [Date::MONTHNAMES[month].center(20), "Su Mo Tu We Th Fr Sa"]
   # Make array of 42 days, starting with Sunday.
   days = []
   date.wday.times { days.push "  " }
   while date.month == month
     days.push("%2d" % date.mday)
     date += 1
   end
   (42 - days.length).times { days.push "  " }
   days.each_slice(7) { |week| rows.push(week.join " ") }
   next rows
 end
 # Calculate months per row (mpr).
 #  1. Divide columns by 22 columns per month, rounded down. (Pretend
 #     to have 2 extra columns; last month uses only 20 columns.)
 #  2. Decrease mpr if 12 months would fit in the same months per
 #     column (mpc). For example, if we can fit 5 mpr and 3 mpc, then
 #     we use 4 mpr and 3 mpc.
 mpr = (columns + 2).div 22
 mpr = 12.div((12 + mpr - 1).div mpr)
 # Use 20 columns per month + 2 spaces between months.
 width = mpr * 22 - 2
 # Join months into calendar.
 rows = ["[Snoopy]".center(width), "#{year}".center(width)]
 months.each_slice(mpr) do |slice|
   slice[0].each_index do |i|
     rows.push(slice.map {|a| a[i]}.join "  ")
   end
 end
 return rows.join("\n")

end


ARGV.length == 1 or abort "usage: #{$0} year"

  1. Guess width of terminal.
  2. 1. Obey environment variable COLUMNS.
  3. 2. Try to require 'io/console' from Ruby 1.9.3.
  4. 3. Try to run `tput co`.
  5. 4. Assume 80 columns.

columns = begin Integer(ENV["COLUMNS"] || "")

         rescue
           begin require 'io/console'; IO.console.winsize[1]
           rescue LoadError
             begin Integer(`tput co`)
             rescue
               80; end; end; end

puts cal(Integer(ARGV[0]), columns)</lang>

Here is 1969 in 132 columns.

$ ruby cal.rb 1969                                                             
                                                             [Snoopy]                                                             
                                                               1969                                                               
      January               February               March                 April                  May                   June        
Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa
          1  2  3  4                     1                     1         1  2  3  4  5               1  2  3   1  2  3  4  5  6  7
 5  6  7  8  9 10 11   2  3  4  5  6  7  8   2  3  4  5  6  7  8   6  7  8  9 10 11 12   4  5  6  7  8  9 10   8  9 10 11 12 13 14
12 13 14 15 16 17 18   9 10 11 12 13 14 15   9 10 11 12 13 14 15  13 14 15 16 17 18 19  11 12 13 14 15 16 17  15 16 17 18 19 20 21
19 20 21 22 23 24 25  16 17 18 19 20 21 22  16 17 18 19 20 21 22  20 21 22 23 24 25 26  18 19 20 21 22 23 24  22 23 24 25 26 27 28
26 27 28 29 30 31     23 24 25 26 27 28     23 24 25 26 27 28 29  27 28 29 30           25 26 27 28 29 30 31  29 30               
                                            30 31                                                                                 
        July                 August              September              October               November              December      
Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa
       1  2  3  4  5                  1  2      1  2  3  4  5  6            1  2  3  4                     1      1  2  3  4  5  6
 6  7  8  9 10 11 12   3  4  5  6  7  8  9   7  8  9 10 11 12 13   5  6  7  8  9 10 11   2  3  4  5  6  7  8   7  8  9 10 11 12 13
13 14 15 16 17 18 19  10 11 12 13 14 15 16  14 15 16 17 18 19 20  12 13 14 15 16 17 18   9 10 11 12 13 14 15  14 15 16 17 18 19 20
20 21 22 23 24 25 26  17 18 19 20 21 22 23  21 22 23 24 25 26 27  19 20 21 22 23 24 25  16 17 18 19 20 21 22  21 22 23 24 25 26 27
27 28 29 30 31        24 25 26 27 28 29 30  28 29 30              26 27 28 29 30 31     23 24 25 26 27 28 29  28 29 30 31         
                      31                                                                30                                        

The output in 80 columns is similar, except that there are only three months per row, and the "[Snoopy]" and "1969" are centered above February.

Scala

Library: Scala

Scala Version 1

<lang Scala>import java.util.{ Calendar, GregorianCalendar } import language.postfixOps import collection.mutable.ListBuffer

object CalendarPrint extends App {

 val locd = java.util.Locale.getDefault()
 val cal = new GregorianCalendar
 val monthsMax = cal.getMaximum(Calendar.MONTH)
 def JDKweekDaysToISO(dn: Int) = {
   val nday = dn - Calendar.MONDAY
   if (nday < 0) (dn + Calendar.THURSDAY) else nday
 }
 def daysInMonth(year: Int, monthMinusOne: Int): Int = {
   cal.set(year, monthMinusOne, 1)
   cal.getActualMaximum(Calendar.DAY_OF_MONTH)
 }
 def namesOfMonths() = {
   def f1(i: Int): String = {
     cal.set(2013, i, 1)
     cal.getDisplayName(Calendar.MONTH, Calendar.LONG, locd)
   }
   (0 to monthsMax) map f1
 }
 def offsets(year: Int): List[Int] = {
   val months = cal.getMaximum(Calendar.MONTH)
   def get1stDayOfWeek(i: Int) = {
     cal.set(year, i, 1)
     cal.get(Calendar.DAY_OF_WEEK)
   }
   (0 to monthsMax).toList map get1stDayOfWeek map { i => JDKweekDaysToISO(i) }
 }
 def headerNameOfDays() = {
   val mdow = cal.getDisplayNames(Calendar.DAY_OF_WEEK, Calendar.SHORT, locd) // map days of week
   val it = mdow.keySet.iterator
   val keySet = new ListBuffer[String]
   while (it.hasNext) keySet += it.next
   (keySet.map { key => (JDKweekDaysToISO(mdow.get(key)), key.take(2))
   }.sortWith(_._1 < _._1) map (_._2)).mkString(" ")
 }
 def getGregCal(year: Int) = {
   {
     def dayOfMonth(month: Int) = new Iterator[(Int, Int)] {
       cal.set(year, month, 1)
       var ldom = 0
       def next() = {
         val res = (cal.get(Calendar.MONTH), cal.get(Calendar.DAY_OF_MONTH))
         ldom = res._2
         cal.roll(Calendar.DAY_OF_MONTH, true)
         res
       }
       def hasNext() = (cal.get(Calendar.DAY_OF_MONTH) > ldom)
     }
     var ret: List[(Int, Int)] = Nil
     for (i <- 0 to monthsMax) ret = ret ++ (dayOfMonth(i).toSeq)
     (ret, offsets(year))
   }
 }
 def printCalendar(calendar: (List[(Int, Int)], List[Int]),
                   headerList: List[String] = Nil,
                   printerWidth: Int = 80) = {
   val mw = 20 // month width
   val gwf = 2 // gap width fixed
   val gwm = 2 // gap width minimum
   val fgw = true
   val arr = Array.ofDim[String](6, 7)
   def limits(printerWidth: Int): (Int, Int, Int, Int, Int) = {
     val pw = if (printerWidth < 20) 20 else if (printerWidth > 300) 300 else printerWidth
     // months side by side, gaps sum minimum
     val (msbs, gsm) = {
       val x1 = {
         val c = if (pw / mw > 12) 12 else pw / mw
         val a = (c - 1)
         if (c * mw + a * gwm <= pw) c else a
       } match {
         case 5                      => 4
         case a if (a > 6 && a < 12) => 6
         case other                  => other
       }
       (x1, (x1 - 1) * gwm)
     }
     def getFGW(msbs: Int, gsm: Int) = { val r = (pw - msbs * mw - gsm) / 2; (r, gwf, r) } // fixed gap width
     def getVGW(msbs: Int, gsm: Int) = pw - msbs * mw - gsm match { // variable gap width
       case a if (a < 2 * gwm) => (a / 2, gwm, a / 2)
       case b                  => { val x = (b + gsm) / (msbs + 1); (x, x, x) }
     }
     // left margin, gap width, right margin
     val (lm, gw, rm) = if (fgw) getFGW(msbs, gsm) else getVGW(msbs, gsm)
     (pw, msbs, lm, gw, rm)
   } // def limits(
   val (pw, msbs, lm, gw, rm) = limits(printerWidth)
   val monthsList = (0 to monthsMax).map { m => calendar._1.filter { _._1 == m } }
   val nom = namesOfMonths()
   val hnod = headerNameOfDays
   def fsplit(list: List[(Int, Int)]): List[String] = {
     def fap(p: Int) = (p / 7, p % 7)
     for (i <- 0 until 6) for (j <- 0 until 7) arr(i)(j) = "  "
     for (i <- 0 until list.size)
       arr(fap(i + calendar._2(list(i)._1))._1)(fap(i + calendar._2(list(i)._1))._2) =
         f"${(list(i)._2)}%2d"
     arr.toList.map(_.foldRight("")(_ + " " + _))
   }
   val monthsRows = monthsList.map(fsplit)
   def center(s: String, l: Int): String = {
     (if (s.size >= l) s
     else " " * ((l - s.size) / 2) + s + " " * ((l - s.size) / 2) + " ").substring(0, l)
   }
   val maxMonths = monthsMax + 1
   val rowblocks = (1 to maxMonths / msbs).map { i =>
     (0 to 5).map { j =>
       val lb = new ListBuffer[String]
       val k = (i - 1) * msbs
       (k to k + msbs - 1).map { l => lb += monthsRows(l)(j) }
       lb
     }
   }
   val mheaders = (1 to maxMonths / msbs).
     map { i => (0 to msbs - 1).map { j => center(nom(j + (i - 1) * msbs), 20) } }
   val dowheaders = (1 to maxMonths / msbs).
     map { i => (0 to msbs - 1).map { j => center(hnod, 20) } }
   headerList.foreach(xs => println(center(xs + '\n', pw)))
   (1 to 12 / msbs).foreach { i =>
     println(" " * lm + mheaders(i - 1).foldRight("")(_ + " " * gw + _))
     println(" " * lm + dowheaders(i - 1).foldRight("")(_ + " " * gw + _))
     rowblocks(i - 1).foreach { xs => println(" " * lm + xs.foldRight("")(_ + " " * (gw - 1) + _)) }
     println
   }
 } //  def printCal(
 printCalendar(getGregCal(1969), List("[Snoopy Picture]", "1969"))
 printCalendar(getGregCal(1582), List("[Snoopy Picture]", "1582"), printerWidth = 132)

}</lang>

Output:
                               [Snoopy Picture]
                                
                                     1969
                                      
              January               February               March          
        Mo Tu We Th Fr Sa Su  Mo Tu We Th Fr Sa Su  Mo Tu We Th Fr Sa Su  
               1  2  3  4  5                  1  2                  1  2  
         6  7  8  9 10 11 12   3  4  5  6  7  8  9   3  4  5  6  7  8  9  
        13 14 15 16 17 18 19  10 11 12 13 14 15 16  10 11 12 13 14 15 16  
        20 21 22 23 24 25 26  17 18 19 20 21 22 23  17 18 19 20 21 22 23  
        27 28 29 30 31        24 25 26 27 28        24 25 26 27 28 29 30  
                                                    31                    

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

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

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

                                                         [Snoopy Picture]
                                                          
                                                               1582
                                                                
       January               February               March                 April                  May                   June          
 Mo Tu We Th Fr Sa Su  Mo Tu We Th Fr Sa Su  Mo Tu We Th Fr Sa Su  Mo Tu We Th Fr Sa Su  Mo Tu We Th Fr Sa Su  Mo Tu We Th Fr Sa Su  
  1  2  3  4  5  6  7            1  2  3  4            1  2  3  4                     1      1  2  3  4  5  6               1  2  3  
  8  9 10 11 12 13 14   5  6  7  8  9 10 11   5  6  7  8  9 10 11   2  3  4  5  6  7  8   7  8  9 10 11 12 13   4  5  6  7  8  9 10  
 15 16 17 18 19 20 21  12 13 14 15 16 17 18  12 13 14 15 16 17 18   9 10 11 12 13 14 15  14 15 16 17 18 19 20  11 12 13 14 15 16 17  
 22 23 24 25 26 27 28  19 20 21 22 23 24 25  19 20 21 22 23 24 25  16 17 18 19 20 21 22  21 22 23 24 25 26 27  18 19 20 21 22 23 24  
 29 30 31              26 27 28              26 27 28 29 30 31     23 24 25 26 27 28 29  28 29 30 31           25 26 27 28 29 30     
                                                                   30                                                                

         July                 August              September              October               November              December        
 Mo Tu We Th Fr Sa Su  Mo Tu We Th Fr Sa Su  Mo Tu We Th Fr Sa Su  Mo Tu We Th Fr Sa Su  Mo Tu We Th Fr Sa Su  Mo Tu We Th Fr Sa Su  
                    1         1  2  3  4  5                  1  2   1  2  3  4 15 16 17   1  2  3  4  5  6  7         1  2  3  4  5  
  2  3  4  5  6  7  8   6  7  8  9 10 11 12   3  4  5  6  7  8  9  18 19 20 21 22 23 24   8  9 10 11 12 13 14   6  7  8  9 10 11 12  
  9 10 11 12 13 14 15  13 14 15 16 17 18 19  10 11 12 13 14 15 16  25 26 27 28 29 30 31  15 16 17 18 19 20 21  13 14 15 16 17 18 19  
 16 17 18 19 20 21 22  20 21 22 23 24 25 26  17 18 19 20 21 22 23                        22 23 24 25 26 27 28  20 21 22 23 24 25 26  
 23 24 25 26 27 28 29  27 28 29 30 31        24 25 26 27 28 29 30                        29 30                 27 28 29 30 31        
 30 31                                                                                                                               

Scala Version 2

Works with: Scala version 2.10.1

<lang Scala>/**

* Loosely based on the Ruby implementation.
*
* Focuses on immutability and Scala idioms,
* while trying to remain readable and clean.
*/

object YearCalendarApp extends App with Extras {

 val defaultYear = 1752
 val columns = 86
 val year = args.headOption.map(_.toInt).getOrElse(defaultYear)
 yearCalendarLines(year, columns).foreach(println)
 def yearCalendarLines(year: Int, columns: Int): Seq[String] = {
   // At least one. Divide rest columns by width + 2 spaces (separator)
   val calendarsPerRow = 1 + (columns - 20) / (20 + 2)
   // Use 20 columns per month + 2 spaces between months
   val width = calendarsPerRow * 22 - 2
   List(
     "[Snoopy]".center(width),
     s"${year}".center(width)) ++
     // Get, group, transpose and join calendar lines
     allMonthCalendarLines(year).grouped(calendarsPerRow).flatMap { calGroup =>
       calGroup.transpose.map(stringsInRow => stringsInRow.mkString("  "))
     }
 }
 def allMonthCalendarLines(year: Int): Seq[Seq[String]] = {
   (1 to 12).map { monthNr =>
     val date = MonthCalendar(monthInYear = monthNr, year)
     // Make array of 42 days (7 * 6 weeks max.) starting with Sunday (which is 0)
     val daySlotsInMonth = {
       (Seq().padTo(date.dayOfWeek, "  ") ++
         date.daysInMonth.map { dayNr => "%2d".format(dayNr) }).
         padTo(42, "  ")
     }
     List(
       date.monthName.center(20),
       "Su Mo Tu We Th Fr Sa") ++
       daySlotsInMonth.grouped(7).map { weekSlots => weekSlots.mkString(" ") }
   }
 }

}</lang>

<lang Scala>/**

* This provides extra classes needed for the main
* algorithm.
*/

trait Extras {

 import java.util.Calendar
 import java.util.GregorianCalendar
 import java.text.SimpleDateFormat
 import java.util.Locale
 import scala.collection.mutable.Buffer
 implicit class MyString(str: String) {
   def center(width: Int): String = {
     val leftSpaces = (width / 2) - (str.length() / 2)
     val rightSpaces = width - (leftSpaces + str.length)
     (" " * leftSpaces) + str + (" " * rightSpaces)
   }
 }
 case class MonthCalendar(monthInYear: Int, year: Int) {
   private val javaCalendar = makeJavaCalendar(year, monthInYear)
   private def makeJavaCalendar(year: Int, monthInYear: Int): Calendar = {
     val calendar = new GregorianCalendar()
     // Actually, other countries changed already in 1582,
     // which is the JDK's default implementation.
     val gregorianDateChangeInEngland = {
       val d = Calendar.getInstance()
       d.set(1752, Calendar.SEPTEMBER, 14)
       d.getTime()
     }
     // For England we need to set this explicitly.
     calendar.setGregorianChange(gregorianDateChangeInEngland)
     calendar.set(Calendar.DAY_OF_MONTH, 1)
     calendar.set(Calendar.YEAR, year)
     calendar.set(Calendar.MONTH, monthInYear - 1)
     calendar
   }
   val monthName = javaCalendar.getDisplayName(Calendar.MONTH, Calendar.LONG, Locale.ENGLISH)
   val dayOfWeek = javaCalendar.get(Calendar.DAY_OF_WEEK) - 1
   val daysInMonth = {
     val tempCal = makeJavaCalendar(year, monthInYear)
     val dayNumbers = Buffer[Int]()
     while (tempCal.get(Calendar.MONTH) == monthInYear - 1) {
       dayNumbers += tempCal.get(Calendar.DAY_OF_MONTH)
       tempCal.add(Calendar.DATE, 1)
     }
     dayNumbers
   }
 }

}</lang>

Sample output for 1792:

                                       [Snoopy]                                       
                                         1752                                         
       January              February                March                 April       
Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa
          1  2  3  4                     1   1  2  3  4  5  6  7            1  2  3  4
 5  6  7  8  9 10 11   2  3  4  5  6  7  8   8  9 10 11 12 13 14   5  6  7  8  9 10 11
12 13 14 15 16 17 18   9 10 11 12 13 14 15  15 16 17 18 19 20 21  12 13 14 15 16 17 18
19 20 21 22 23 24 25  16 17 18 19 20 21 22  22 23 24 25 26 27 28  19 20 21 22 23 24 25
26 27 28 29 30 31     23 24 25 26 27 28 29  29 30 31              26 27 28 29 30      
                                                                                      
         May                  June                  July                 August       
Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa
                1  2      1  2  3  4  5  6            1  2  3  4                     1
 3  4  5  6  7  8  9   7  8  9 10 11 12 13   5  6  7  8  9 10 11   2  3  4  5  6  7  8
10 11 12 13 14 15 16  14 15 16 17 18 19 20  12 13 14 15 16 17 18   9 10 11 12 13 14 15
17 18 19 20 21 22 23  21 22 23 24 25 26 27  19 20 21 22 23 24 25  16 17 18 19 20 21 22
24 25 26 27 28 29 30  28 29 30              26 27 28 29 30 31     23 24 25 26 27 28 29
31                                                                30 31               
      September              October              November              December      
Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa
       1  2 14 15 16   1  2  3  4  5  6  7            1  2  3  4                  1  2
17 18 19 20 21 22 23   8  9 10 11 12 13 14   5  6  7  8  9 10 11   3  4  5  6  7  8  9
24 25 26 27 28 29 30  15 16 17 18 19 20 21  12 13 14 15 16 17 18  10 11 12 13 14 15 16
                      22 23 24 25 26 27 28  19 20 21 22 23 24 25  17 18 19 20 21 22 23
                      29 30 31              26 27 28 29 30        24 25 26 27 28 29 30
                                                                  31

Seed7

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

 include "time.s7i";

const func string: center (in string: stri, in integer: length) is

 return ("" lpad (length - length(stri)) div 2 <& stri) rpad length;

const proc: printCalendar (in integer: year, in integer: cols) is func

 local
   var time: date is time.value;
   var integer: dayOfWeek is 0;
   const array string: monthNames is [] ("January", "February", "March", "April", "May", "June",
       "July", "August", "September", "October", "November", "December"); 
   var array array string: monthTable is 12 times 9 times "";
   var string: str is "";
   var integer: month is 0;
   var integer: position is 0;
   var integer: row is 0;
   var integer: column is 0;
   var integer: line is 0;
 begin
   for month range 1 to 12 do
     monthTable[month][1] := " " & center(monthNames[month], 20);
     monthTable[month][2] := " Mo Tu We Th Fr Sa Su";
     date := date(year, month, 1);
     dayOfWeek := dayOfWeek(date);
     for position range 1 to 43 do
       if position >= dayOfWeek and position - dayOfWeek < daysInMonth(date.year, date.month) then
         str := succ(position - dayOfWeek) lpad 3;
       else
         str := "" lpad 3;
       end if;
       monthTable[month][3 + pred(position) div 7] &:= str;
     end for;
   end for;
   writeln(center("[Snoopy Picture]", cols * 24 + 4));
   writeln(center(str(year),cols * 24 + 4));
   writeln;
   for row range 1 to succ(11 div cols) do
     for line range 1 to 9 do
       for column range 1 to cols do
         if pred(row) * cols + column <= 12 then
           write("   " & monthTable[pred(row) * cols + column][line]);
         end if;
       end for;
       writeln;
     end for;
   end for;
 end func;

const proc: main is func

 begin
   printCalendar(1969, 3);
 end func;</lang>

Original source: [1]

The output of this program is:

                              [Snoopy Picture]                              
                                    1969                                    

          January                 February                 March        
    Mo Tu We Th Fr Sa Su    Mo Tu We Th Fr Sa Su    Mo Tu We Th Fr Sa Su
           1  2  3  4  5                    1  2                    1  2
     6  7  8  9 10 11 12     3  4  5  6  7  8  9     3  4  5  6  7  8  9
    13 14 15 16 17 18 19    10 11 12 13 14 15 16    10 11 12 13 14 15 16
    20 21 22 23 24 25 26    17 18 19 20 21 22 23    17 18 19 20 21 22 23
    27 28 29 30 31          24 25 26 27 28          24 25 26 27 28 29 30
                                                    31                  
                  
           April                    May                     June        
    Mo Tu We Th Fr Sa Su    Mo Tu We Th Fr Sa Su    Mo Tu We Th Fr Sa Su
        1  2  3  4  5  6              1  2  3  4                       1
     7  8  9 10 11 12 13     5  6  7  8  9 10 11     2  3  4  5  6  7  8
    14 15 16 17 18 19 20    12 13 14 15 16 17 18     9 10 11 12 13 14 15
    21 22 23 24 25 26 27    19 20 21 22 23 24 25    16 17 18 19 20 21 22
    28 29 30                26 27 28 29 30 31       23 24 25 26 27 28 29
                                                    30                  
                  
            July                   August                September      
    Mo Tu We Th Fr Sa Su    Mo Tu We Th Fr Sa Su    Mo Tu We Th Fr Sa Su
        1  2  3  4  5  6                 1  2  3     1  2  3  4  5  6  7
     7  8  9 10 11 12 13     4  5  6  7  8  9 10     8  9 10 11 12 13 14
    14 15 16 17 18 19 20    11 12 13 14 15 16 17    15 16 17 18 19 20 21
    21 22 23 24 25 26 27    18 19 20 21 22 23 24    22 23 24 25 26 27 28
    28 29 30 31             25 26 27 28 29 30 31    29 30               
                                                                        
                  
          October                 November                December      
    Mo Tu We Th Fr Sa Su    Mo Tu We Th Fr Sa Su    Mo Tu We Th Fr Sa Su
           1  2  3  4  5                    1  2     1  2  3  4  5  6  7
     6  7  8  9 10 11 12     3  4  5  6  7  8  9     8  9 10 11 12 13 14
    13 14 15 16 17 18 19    10 11 12 13 14 15 16    15 16 17 18 19 20 21
    20 21 22 23 24 25 26    17 18 19 20 21 22 23    22 23 24 25 26 27 28
    27 28 29 30 31          24 25 26 27 28 29 30    29 30 31            
                                                                        
                  

Tcl

Due to the prevalence of 80 column devices instead of 132 column ones, this code produces 3 months at a time instead of 4. <lang tcl>package require Tcl 8.5

  1. Produce information about the days in a month, without any assumptions about
  2. what those days actually are.

proc calMonthDays {timezone locale year month} {

   set days {}
   set moment [clock scan [format "%04d-%02d-00 12:00" $year $month] \

-timezone $timezone -locale $locale -format "%Y-%m-%d %H:%M"]

   while 1 {

set moment [clock add $moment 1 day] lassign [clock format $moment -timezone $timezone -locale $locale \ -format "%m %d %u"] m d dow if {[scan $m %d] != $month} { return $days } lappend days $moment [scan $d %d] $dow

   }

}

proc calMonth {year month timezone locale} {

   set dow 0
   set line ""
   set lines {}
   foreach {t day dayofweek} [calMonthDays $timezone $locale $year $month] {

if {![llength $lines]} {lappend lines $t} if {$dow > $dayofweek} { lappend lines [string trimright $line] set line "" set dow 0 } while {$dow < $dayofweek-1} { append line " " incr dow } append line [format "%2d " $day] set dow $dayofweek

   }
   lappend lines [string trimright $line]

}

proc cal3Month {year month timezone locale} {

   # Extract the month data
   set d1 [lassign [calMonth $year $month $timezone $locale] t1]; incr month
   set d2 [lassign [calMonth $year $month $timezone $locale] t2]; incr month
   set d3 [lassign [calMonth $year $month $timezone $locale] t3]
   # Print the header line of month names
   foreach t [list $t1 $t2 $t3] {

set m [clock format $t -timezone $timezone -locale $locale -format "%B"] set l [expr {10 + [string length $m]/2}] puts -nonewline [format "%-25s" [format "%*s" $l $m]]

   }
   puts ""
   # Print the month days
   foreach l1 $d1 l2 $d2 l3 $d3 {

puts [format "%-25s%-25s%s" $l1 $l2 $l3]

   }

}

proc cal {{year ""} {timezone :localtime} {locale en}} {

   if {$year eq ""} {

set year [clock format [clock seconds] -format %Y]

   }
   puts [format "%40s" "-- $year --"]
   foreach m {1 4 7 10} {

puts "" cal3Month $year $m $timezone $locale

   }

}

proc snoopy {} {

   puts [format "%43s\n" {[Snoopy Picture]}]

}

snoopy cal</lang> Which produces this output:

                           [Snoopy Picture]

                              -- 2011 --

      January                  February                  March             
                1  2         1  2  3  4  5  6         1  2  3  4  5  6
 3  4  5  6  7  8  9      7  8  9 10 11 12 13      7  8  9 10 11 12 13
10 11 12 13 14 15 16     14 15 16 17 18 19 20     14 15 16 17 18 19 20
17 18 19 20 21 22 23     21 22 23 24 25 26 27     21 22 23 24 25 26 27
24 25 26 27 28 29 30     28                       28 29 30 31
31                                                

       April                     May                      June             
             1  2  3                        1            1  2  3  4  5
 4  5  6  7  8  9 10      2  3  4  5  6  7  8      6  7  8  9 10 11 12
11 12 13 14 15 16 17      9 10 11 12 13 14 15     13 14 15 16 17 18 19
18 19 20 21 22 23 24     16 17 18 19 20 21 22     20 21 22 23 24 25 26
25 26 27 28 29 30        23 24 25 26 27 28 29     27 28 29 30
                         30 31                    

        July                    August                 September           
             1  2  3      1  2  3  4  5  6  7               1  2  3  4
 4  5  6  7  8  9 10      8  9 10 11 12 13 14      5  6  7  8  9 10 11
11 12 13 14 15 16 17     15 16 17 18 19 20 21     12 13 14 15 16 17 18
18 19 20 21 22 23 24     22 23 24 25 26 27 28     19 20 21 22 23 24 25
25 26 27 28 29 30 31     29 30 31                 26 27 28 29 30

      October                  November                 December           
                1  2         1  2  3  4  5  6               1  2  3  4
 3  4  5  6  7  8  9      7  8  9 10 11 12 13      5  6  7  8  9 10 11
10 11 12 13 14 15 16     14 15 16 17 18 19 20     12 13 14 15 16 17 18
17 18 19 20 21 22 23     21 22 23 24 25 26 27     19 20 21 22 23 24 25
24 25 26 27 28 29 30     28 29 30                 26 27 28 29 30 31
31                                                

If a different year is chosen, it's printed… <lang tcl>snoopy cal 1969</lang>

                           [Snoopy Picture]

                              -- 1969 --

      January                  February                  March             
       1  2  3  4  5                     1  2                     1  2
 6  7  8  9 10 11 12      3  4  5  6  7  8  9      3  4  5  6  7  8  9
13 14 15 16 17 18 19     10 11 12 13 14 15 16     10 11 12 13 14 15 16
20 21 22 23 24 25 26     17 18 19 20 21 22 23     17 18 19 20 21 22 23
27 28 29 30 31           24 25 26 27 28           24 25 26 27 28 29 30
                                                  31

       April                     May                      June             
    1  2  3  4  5  6               1  2  3  4                        1
 7  8  9 10 11 12 13      5  6  7  8  9 10 11      2  3  4  5  6  7  8
14 15 16 17 18 19 20     12 13 14 15 16 17 18      9 10 11 12 13 14 15
21 22 23 24 25 26 27     19 20 21 22 23 24 25     16 17 18 19 20 21 22
28 29 30                 26 27 28 29 30 31        23 24 25 26 27 28 29
                                                  30

        July                    August                 September           
    1  2  3  4  5  6                  1  2  3      1  2  3  4  5  6  7
 7  8  9 10 11 12 13      4  5  6  7  8  9 10      8  9 10 11 12 13 14
14 15 16 17 18 19 20     11 12 13 14 15 16 17     15 16 17 18 19 20 21
21 22 23 24 25 26 27     18 19 20 21 22 23 24     22 23 24 25 26 27 28
28 29 30 31              25 26 27 28 29 30 31     29 30

      October                  November                 December           
       1  2  3  4  5                     1  2      1  2  3  4  5  6  7
 6  7  8  9 10 11 12      3  4  5  6  7  8  9      8  9 10 11 12 13 14
13 14 15 16 17 18 19     10 11 12 13 14 15 16     15 16 17 18 19 20 21
20 21 22 23 24 25 26     17 18 19 20 21 22 23     22 23 24 25 26 27 28
27 28 29 30 31           24 25 26 27 28 29 30     29 30 31

The code also handles Julian/Gregorian switch dates correctly, but must be told what locale to format the switch as and for what timezone in that case. For example, Spain was one of the first countries to make the change: <lang tcl>snoopy cal 1582 :Europe/Madrid es_ES</lang>

                           [Snoopy Picture]

                              -- 1582 --

       enero                   febrero                   marzo             
 1  2  3  4  5  6  7               1  2  3  4               1  2  3  4
 8  9 10 11 12 13 14      5  6  7  8  9 10 11      5  6  7  8  9 10 11
15 16 17 18 19 20 21     12 13 14 15 16 17 18     12 13 14 15 16 17 18
22 23 24 25 26 27 28     19 20 21 22 23 24 25     19 20 21 22 23 24 25
29 30 31                 26 27 28                 26 27 28 29 30 31

       abril                     mayo                    junio             
                   1         1  2  3  4  5  6                  1  2  3
 2  3  4  5  6  7  8      7  8  9 10 11 12 13      4  5  6  7  8  9 10
 9 10 11 12 13 14 15     14 15 16 17 18 19 20     11 12 13 14 15 16 17
16 17 18 19 20 21 22     21 22 23 24 25 26 27     18 19 20 21 22 23 24
23 24 25 26 27 28 29     28 29 30 31              25 26 27 28 29 30
30                                                

       julio                    agosto                 septiembre          
                   1            1  2  3  4  5                     1  2
 2  3  4  5  6  7  8      6  7  8  9 10 11 12      3  4  5  6  7  8  9
 9 10 11 12 13 14 15     13 14 15 16 17 18 19     10 11 12 13 14 15 16
16 17 18 19 20 21 22     20 21 22 23 24 25 26     17 18 19 20 21 22 23
23 24 25 26 27 28 29     27 28 29 30 31           24 25 26 27 28 29 30
30 31                                             

      octubre                 noviembre                diciembre           
 1  2  3  4 15 16 17      1  2  3  4  5  6  7            1  2  3  4  5
18 19 20 21 22 23 24      8  9 10 11 12 13 14      6  7  8  9 10 11 12
25 26 27 28 29 30 31     15 16 17 18 19 20 21     13 14 15 16 17 18 19
                         22 23 24 25 26 27 28     20 21 22 23 24 25 26
                         29 30                    27 28 29 30 31

As can be seen, a Real Programmer has many intricacies to deal with!

UNIX Shell

All Unix variations come with the cal command which makes the task very easy. <lang bash>

  1. !/bin/sh

echo "Snoopy goes here" cal 1969 </lang>

Output produced:

Snoopy goes here
                             1969

      January               February               March
Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa
          1  2  3  4                     1                     1
 5  6  7  8  9 10 11   2  3  4  5  6  7  8   2  3  4  5  6  7  8
12 13 14 15 16 17 18   9 10 11 12 13 14 15   9 10 11 12 13 14 15
19 20 21 22 23 24 25  16 17 18 19 20 21 22  16 17 18 19 20 21 22
26 27 28 29 30 31     23 24 25 26 27 28     23 24 25 26 27 28 29
                                            30 31
       April                  May                   June
Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa
       1  2  3  4  5               1  2  3   1  2  3  4  5  6  7
 6  7  8  9 10 11 12   4  5  6  7  8  9 10   8  9 10 11 12 13 14
13 14 15 16 17 18 19  11 12 13 14 15 16 17  15 16 17 18 19 20 21
20 21 22 23 24 25 26  18 19 20 21 22 23 24  22 23 24 25 26 27 28
27 28 29 30           25 26 27 28 29 30 31  29 30
                                            
        July                 August              September
Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa
       1  2  3  4  5                  1  2      1  2  3  4  5  6
 6  7  8  9 10 11 12   3  4  5  6  7  8  9   7  8  9 10 11 12 13
13 14 15 16 17 18 19  10 11 12 13 14 15 16  14 15 16 17 18 19 20
20 21 22 23 24 25 26  17 18 19 20 21 22 23  21 22 23 24 25 26 27
27 28 29 30 31        24 25 26 27 28 29 30  28 29 30
                      31                    
      October               November              December
Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa  Su Mo Tu We Th Fr Sa
          1  2  3  4                     1      1  2  3  4  5  6
 5  6  7  8  9 10 11   2  3  4  5  6  7  8   7  8  9 10 11 12 13
12 13 14 15 16 17 18   9 10 11 12 13 14 15  14 15 16 17 18 19 20
19 20 21 22 23 24 25  16 17 18 19 20 21 22  21 22 23 24 25 26 27
26 27 28 29 30 31     23 24 25 26 27 28 29  28 29 30 31
                      30                    

Vedit macro language

This implementation uses the calendar.vdm macro that comes with Vedit. (So it serves as an example of how to call other macros from a macro.) See CALENDAR task for a stand-alone version.
Calendar.vdm draws one month calendar. That is then copied as columnar block and pasted to the 1969 calendar.

<lang vedit>Buf_Switch(Buf_Free) Config_Tab(5,30,55)

  1. 9 = 1 // first day of week: 0=Su, 1=Mo
  2. 3 = 3 // number of months per line
  3. 2 = 1969 // year
  4. 1 = 1 // starting month

Repeat(12/#3) {

   Repeat (#3) {
       Buf_Switch(Buf_Free)
       Call_File(122, "calendar.vdm", "DRAW_CALENDAR")
       Reg_Copy_Block(10, 1, EOB_Pos, COLSET, 1, 21)
       Buf_Quit(OK)
       EOL Ins_Char(9)
       #5 = Cur_Pos
       Reg_Ins(10)
       Goto_Pos(#5)
       #1++
   }
   EOF
   Ins_Newline(2)

} </lang>

The code above creates calendar for 80x43 display. For 132 column display, change #3 (number of months per line) to 4 or 6, and adjust the tab positions if required. The following would work with all widhts, but the left/right margin would not be balanced. <lang vedit>Config_Tab(22)</lang>

Output:

        January   1969           February  1969           March     1969

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

        April     1969           May       1969           June      1969

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

        July      1969           August    1969           September 1969

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


        October   1969           November  1969           December  1969

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

XPL0

<lang XPL0>include c:\cxpl\codes; \intrinsic 'code' declarations

func WeekDay(Year, Month, Day); \Return day of week (0=Sun 1=Mon..6=Sat) int Year, Month, Day; \Works for years from 1583 onward [if Month<=2 then [Month:= Month+12; Year:= Year-1]; return rem((Day-1 + (Month+1)*26/10 + Year + Year/4 + Year/100*6 + Year/400)/7); ];

proc Space(N); \Display N space characters int N; while N do [ChOut(0, ^ ); N:= N-1];

proc Calendar(Year); \Display calendar for specified year int Year; int Month, Col, C, Line, MoName, Days, DayMax, Day(3); [MoName:= [

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

Space(35); Text(0, "[Snoopy]"); CrLf(0); Space(37); IntOut(0, Year); CrLf(0); CrLf(0); for Month:= 1 to 12 do

 [for Col:= 0 to 3-1 do
   [Space(5);  Text(0, MoName(Month+Col-1));  Space(7);
   if Col<2 then Space(8);
   ];
 CrLf(0);
 for Col:= 0 to 3-1 do
   [Text(0, "Su Mo Tu We Th Fr Sa");
   if Col<2 then Space(9);
   ];
 CrLf(0);
 for Col:= 0 to 3-1 do         \day of first Sunday of month (can be negative)
   Day(Col):= 1 - WeekDay(Year, Month+Col, 1);
 for Line:= 0 to 6-1 do
   [for Col:= 0 to 3-1 do
     [Days:= [0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
     DayMax:= Days(Month+Col);
     if Month+Col=2 & (rem(Year/4)=0 & rem(Year/100)#0 ! rem(Year/400)=0) then
       DayMax:= DayMax+1;      \if February and leap year then add a day
     for C:= 0 to 7-1 do
       [if Day(Col)>=1 & Day(Col)<=DayMax then
         [IntOut(0, Day(Col));
         if Day(Col)<10 then Space(1); \left justify
         ]
       else Space(2);          \suppress out of range days
       Space(1);
       Day(Col):= Day(Col)+1;
       ];
     if Col<2 then Space(8);
     ];
   CrLf(0);
   ];
 CrLf(0);
 Month:= Month+2;              \2+1 months per Col(umn)
 ];

];

Calendar(1969)</lang>

Output:
                                   [Snoopy]
                                     1969

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

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

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

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