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Doomsday rule: Difference between revisions
→{{header|REXX}}: added the computer programming language REXX.
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(→{{header|REXX}}: added the computer programming language REXX.) |
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Conway - 2101-04-02 is a: Saturday
Builtin - 2101-04-02 is a: Saturday
</pre>
=={{header|REXX}}==
<lang rexx>/*REXX program finds the day─of─week for a specified date using Conway's Doomsday rule. */
parse arg $ /*obtain optional arguments from the CL*/
if $='' | $="," then $= , /*Not specified? Then use the default.*/
'01/06/1800 03/29/1875 12/07/1915 12/23/1970 05/14/2043 04/02/2077 04/02/2101'
d= 'Sun Mon Tues Wednes Thurs Fri Satur' /*list of days of the week, sans "day".*/
y.0= 3 7 7 4 2 6 4 1 5 3 7 5 /*doomsday dates for non-leapyear month*/
y.1= 4 1 7 4 2 6 4 1 5 3 7 5 /* " " " leapyear " */
do j=1 for words($) /*process each of the dates. */
parse value word($, j) with mm '/' dd "/" yy /*parse the date ──► mm dd yy */
ly= leapyear(yy) /*get indication of a leapyear.*/
wd= (doomsday(yy)+dd-word(y.ly, mm) + 7) // 7 + 1 /*obtain code for the weekday. */
say mm'/'dd"/"yy ' falls on ' word(d, wd)"day" /*display day-of-week for date.*/
end /*j*/
exit 0 /*stick a fork in it, we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
doomsday: parse arg ?; return (2 + 5 * (?//4) + 4 * (?//100) + 6 * (?//400) ) // 7
leapyear: arg #; ly= #//4==0; if ly==0 then return 0; return ((#//100\==0) | #//400==0)</lang>
{{out|output|text= when using the default inputs:}}
<pre>
01/06/1800 falls on Monday
03/29/1875 falls on Monday
12/07/1915 falls on Tuesday
12/23/1970 falls on Wednesday
05/14/2043 falls on Thursday
04/02/2077 falls on Friday
04/02/2101 falls on Saturday
</pre>
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