Adriano Allora wrote:
>
> Hi to all,
Hello,
> I've just learnt ( ... anyway, I'm trying to do it) to select a
> string when it is not preceded (or followed) by another string.
Perhaps you should read up on the positive/negative
look-ahead/look-behind assertions in the perlre document.
perldoc perlre
> My aim is to know the mean of text lines in each newsgroup post, so I
> wrote:
>
> #!/usr/bin/perl -w
>
> $nome_del_file = q/text.txt/;
>
> open(INPUT, $nome_del_file);
You should _always_ verify that the file opened successfully.
open INPUT, $nome_del_file or die "Cannot open $nome_del_file: $!";
> $posts = 0;
> $line4post = 0;
>
> while (<INPUT>)
> {
> # it cleans the <return carriage> signs
> tr/\015|\012/\n/;
This translates either a carriage return (\015) or a vertical bar (|) or
a linefeed (\012) to a newline (\n) character. Perhaps you want this
instead:
tr/\015\012/\n/;
> # it makes a lot of <new line> signs only one a time
> tr/\n\r\f\t//s;
You could combine the two transliterations. :-)
tr/\015\012\n\r\f\t/\n\n\n\r\f\t/s;
> # it counts all the posts
> $posts ++ if /Newsgroups: it\..+/;
> # it deletes the headers of each post
> s/Newsgroups: it\..+|Subject: .+|Date: .+|Message-ID: .+|References:
> ..+|From: .+/\n/g;
Or:
$posts++ if s/^Newsgroups: it\..+//;
s/^(?:Subject|Date|Message-ID|References|From):.+/\n/s;
> # THIS ONE DOESN'T WORKS!!! it should count all the lines except the
> lines of division of each post (========\n)
> $line4post ++ if (/\n/ and $´ !~ /={8}/);
$line4post++ unless /={8}\n/;
> }
> print $posts, " posts in ", $line4post, " lines.\nThe mean is ",
> $line4post / $posts, " lines for post.\n";
>
> close(INPUT);
>
> someone knows why for each line of text.txt the Terminal tells me: "Use
> of uninitialized value in pattern match (m//) at [...]" and how can I
^^^^^
At what? Please include the _complete_ warning/error message.
> avoid it?
John
--
use Perl;
program
fulfillment
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