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Active Forums => Programs => Topic started by: Qwerkey on February 05, 2020, 07:48:48 am

Title: Palindromic Dates
Post by: Qwerkey on February 05, 2020, 07:48:48 am
Apparently February 2nd was "International Palindrome Day" because the date was 02/02/2020.  Luckily this is palindromic in both British configuration (DD/MM/YYYY) and American configuration (MM/DD/YYYY).

So I thought that I'd find out which dates have been palindromic.  The program gives a list of palindromic dates from year 0 to 2100.  British date configuration is used, but you can easily adapt it to American configuration.  A text file is created as well as print to screen as there are, not surprisingly, quite a few such dates.

Code: QB64: [Select]
  1. 'Palindromic Dates (British Date Configuration DDMMYYYY) 05/02/2020 by Qwerkey
  2. '02022020 was palindromic
  3. 'Do up to 2100 (assuming gregorian calendar goes back to zero)
  4.  
  5. CONST False = 0, True = NOT False
  6.  
  7. DIM Months%%(12)
  8. FOR N%% = 1 TO 12
  9.     READ Months%%(N%%)
  10. NEXT N%%
  11.  
  12. OPEN "palindate.txt" FOR OUTPUT AS #1
  13.  
  14. Day%% = 1
  15. Month%% = 1
  16. Year% = 0
  17.  
  18. WHILE Year% < 2101
  19.     Palin$ = DayMonth$(Day%%) + DayMonth$(Month%%) + Annus$(Year%)
  20.     IF IsPalindromic%%(Palin$) THEN
  21.         PRINT Palin$
  22.         PRINT #1, Palin$
  23.     END IF
  24.     Day%% = Day%% + 1
  25.     IF Day%% > Months%%(Month%%) THEN
  26.         Day%% = 1
  27.         Month%% = Month%% + 1
  28.         IF Month%% > 12 THEN
  29.             Month%% = 1
  30.             Year% = Year% + 1
  31.             'Modification for leap years:
  32.             IF Year% \ 4 = Year% / 4 THEN
  33.                 Months%%(2) = 29
  34.                 IF Year% \ 400 = Year% / 400 THEN Months%%(2) = 28
  35.             ELSE
  36.                 Months%%(2) = 28
  37.             END IF
  38.         END IF
  39.     END IF
  41.  
  43.  
  44. FUNCTION IsPalindromic%% (P$)
  45.     IsPalindromic%% = True
  46.     M%% = 1
  47.     WHILE M%% <= 4 AND IsPalindromic%%
  48.         IF MID$(P$, M%%, 1) <> MID$(P$, 9 - M%%, 1) THEN IsPalindromic%% = False
  49.         M%% = M%% + 1
  50.     WEND
  52.  
  53. FUNCTION DayMonth$ (M%%)
  54.     S$ = LTRIM$(STR$(M%%))
  55.     IF M%% < 10 THEN
  56.         DayMonth$ = "0" + S$
  57.     ELSE
  58.         DayMonth$ = S$
  59.     END IF
  61.  
  62. FUNCTION Annus$ (Y%)
  63.     A$ = LTRIM$(STR$(Y%))
  64.     IF Y% < 10 THEN
  65.         Annus$ = "000" + A$
  66.     ELSEIF Y% < 100 THEN
  67.         Annus$ = "00" + A$
  68.     ELSEIF Y% < 1000 THEN
  69.         Annus$ = "0" + A$
  70.     ELSE
  71.         Annus$ = A$
  72.     END IF
  74.  
  75. DATA 31,28,31,30,31,30,31,31,30,31,30,31
  76.  
Title: Re: Palindromic Dates
Post by: bplus on February 05, 2020, 09:38:14 am
Wait Groundhog Day, Superbowl Day AND Palindrome Day with BOTH British and American date configurations!

Were all the planets lined up as well? No, just the Republicans. Oh, and the Democrats. ;-))
Title: Re: Palindromic Dates
Post by: Qwerkey on February 05, 2020, 12:22:13 pm
Groundhog Day.  The other day my wife and I asked ourselves "what exactly is Groundhog Day?".  Wikipedia says: "It derives from the Pennsylvania Dutch superstition that if a groundhog emerging from its burrow on this day sees its shadow due to clear weather, it will retreat to its den and winter will persist for six more weeks, and if it does not see its shadow because of cloudiness, spring will arrive early.".  This is a thing that you North Americans want to celebrate??? You're a lot stranger than we thought!

... just the Republicans.  Oh no! Don't set Pete off, please!
Title: Re: Palindromic Dates
Post by: Dimster on February 05, 2020, 05:27:21 pm
And Guy Fawkes Day is completely sane? 11/5 2020 - 5/11/2020 may not be Palindromic but perhaps Pedantic. He says holding a flaming torch, glazed eyes and a Capital building in front of him.
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