On Thu, 2004-05-27 at 06:14, Jim Witte wrote:
> Given a file of words W such as 'cat dog at home ...' (or perhaps read
> into an array, though that would be a very large array), and a set of
> letters L (a string 'aoeuidhtns' - perhaps put into a array), how would
> I write a program to extract all words in W whose letters are all in L?
> I'm thinking of a program to generate a string of words for a
> typing-tutor program.
Hello, Jim.
I'm sorry if this seems complicated, but it really isn't :-) This is a
one-liner that will do precisely what you want (I hope :-) )
perl -pe 'BEGIN{$r=qr/^[asdfghjkl]+$/}split/ /;$_=join" ",grep/$r/,@_'
file
This particular one-liner will search for all words having only letters
from the second alphabetic keyboard row (of qwerty keyboards, at least).
Just to reassure you'll understand what is going on, I'm going to break
the one-liner in some more readable code:
=============================
#!/usr/bin/perl -pw
use strict;
my $r;
BEGIN {
$r = qr/^[asdfghjkl]+$/;
}
split / /;
$_ = join " ", grep /$r/, @_;
=============================
...if you can call that readable...
Now lets go step by step :-)
=============================
#!/usr/bin/perl -pw
# the -p switch will makes all input lines be printed (after being
processed)
use strict;
# I hope you know what this is for
my $r; # this will be our regular expression
BEGIN {
$r = qr/^[asdfghjkl]+$/;
} # and on this BEGIN block we assign it to be a sequence containing
characters from the mentioned row *only*
split / /;
# here we split the input line by spaces (and the result is put into @_)
$_ = join " ", grep /$r/, @_;
# and now we grep the elements that correspond to $r and join them with
spaces
# et voilÃ! the -p switch makes the result be printed
=============================
HTH :-)
jac
> Jim Witte
> [EMAIL PROTECTED]
> Indiana University CS
--
Josà Alves de Castro <[EMAIL PROTECTED]>
Telbit - Tecnologias de InformaÃÃo
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