Re: 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
[download]

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
[download]

Another solution is:

   reverseWord2 =: [:}.@;@|.e.&' ^'<@(' '&,@}.`(0$])@.(2>#));.1]
   reverseWord2 '  one   two three^four    '
four three two one
[download]

In Section Meditations