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Re: Five Ways to Reverse a String of Words (C#, Perl 5, Perl 6, Ruby, Haskell)

by ambrus (Abbot)
on Dec 12, 2006 at 23:06 UTC ( #589445=note: print w/replies, xml ) Need Help??


in reply to Five Ways to Reverse a String of Words (C#, Perl 5, Perl 6, Ruby, Haskell)

The J language isn't particularly strong in string manipulation. You can get an easy solution this way:

reverseWords =: (,' '&,)&:>/@:|.@:;: reverseWords ' one two three four ' four three two one
but it sort of feels like cheating because of the use of the ;: verb which breaks a string to J tokens.

A solution without this cheating is (I have replaced the tab character with a hat for legibility):

reverseWord1 =: [:(,' '&,)&:>/@:|.@:-.&a:e.&' ^'<@}.;.1] reverseWord1 ' one two three^four ' four three two one
Another solution is:
reverseWord2 =: [:}.@;@|.e.&' ^'<@(' '&,@}.`(0$])@.(2>#));.1] reverseWord2 ' one two three^four ' four three two one

Replies are listed 'Best First'.
Re^2: Five Ways to Reverse a String of Words (C#, Perl 5, Perl 6, Ruby, Haskell)
by ambrus (Abbot) on Feb 13, 2009 at 20:21 UTC

    Incidentally, reverseWords =: |.&.;: works as well.

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