Find the last Sunday of each month: Difference between revisions

=={{header|Quackery}}==

<lang Quackery> [ over 3 < if [ 1 - ]

dup 4 / over +

over 100 / -

swap 400 / +

swap 1 -

[ table

0 3 2 5 0 3

5 1 4 6 2 4 ]

+ + 7 mod ] is dayofweek ( day month year --> weekday )

[ dup 400 mod 0 = iff

[ drop true ] done

dup 100 mod 0 = iff

[ drop false ] done

4 mod 0 = ] is leap ( year --> b )

[ swap 1 -

[ table

31 [ dup leap 28 + ]

31 30 31 30 31 31 30

31 30 31 ]

do nip ] is monthdays ( month year --> n )

[ number$

2 times

[ char - join

over 10 < if

[ char 0 join ]

swap number$ join ]

echo$ ] is echoymd ( day month year --> )

[ dip

[ 2dup monthdays

dup temp put

unrot dayofweek ]

- dup 0 < if [ 7 + ]

temp take swap - ] is lastwkday ( month year wkd --> n )

[ temp put

12 times

[ i^ 1+ over

2dup temp share lastwkday

unrot echoymd cr ]

drop temp release ] is lastwkdays ( year wkd --> )

[ 0 lastwkdays ] is lastsundays ( year --> )

2013 lastsundays</lang>

{{out}}

<pre>2013-01-27

2013-02-24

2013-03-31

2013-04-28

2013-05-26

2013-06-30

2013-07-28

2013-08-25

2013-09-29

2013-10-27

2013-11-24

2013-12-29</pre>