Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

I've written some clumsy code to copy a file to stdout (to a web page), and line-wrap it. Some lines in the file are purposefully very long. But we don't want to word-wrap (ala Text::wrap). No, I definitely want to line-wrap at column 80. There must be a more elegant way to do this that this: 
sub display_email
{
    my ($fn) = @_;

    print "<center>file <i>$fn</i></center>\n";
    if ( open( EMAIL, $fn ) ) {

        print "<hr width=600><br>\n<pre>";
        while( $_ =  <EMAIL> ) {
            if (        /^Message-Id:/
                 ||     /^Content-Type:/
                 ||     /^Content-Disposition:/
                 ||     /^Content-Transfer/
                 ||     /^X-[-\w]*:/
                 ||     /^Status: RO/
                 ||     /^Mime-Version:/ ) {
                next;
            }
            if (        /^\s/ && $rcvdflag ) {
                next;
            }
            if (        /^Received:/ ) {
                $rcvdflag = 1;
                next;
            }
            if (        /^[^ ]/ ) {
                $rcvdflag = 0;
            }
            if ( length($_) > 80 ) {
                chop;
                do {
                    print substr( $_, 0, 80 ) . "\n";
                    if (length($_) > 80) {
                        $_ = substr( $_, 80, length($_) - 80 );
                    }
                    else {
                        $_ = "";
                    }
                } while length($_);
            }
            else {
                print $_;
            }
        }
        print "</pre>\n";
        close( EMAIL );
    }
}

[download]
Also, in this sub, the code to not copy all the email header noise lines is also somewhat inelegant. Any sugestions? Criticisms? Regards, -allan

Replies are listed 'Best First'.
Re: how do I line-wrap while copying a file to stdout?
by nardo (Friar) on Apr 20, 2001 at 11:14 UTC 
    chomp;
print join("\n", grep(/./, split(/(.{80})/))), "\n";

    [download]
    The chomp is to get rid of the newline, since we don't really want to count it as a character (i.e. 80 chars + a newline should go on one line even though it's more than 80 chars).
[reply]
[d/l]
      How about: print "$_\n" for /.{1,80}/g;
[reply]
[d/l]
      this seems to drop (not print) the first 80 characters of the very long lines. -allan
[reply]
      I think you had it except for the grep command. I'm not sure what that's there for. I have: 
      chomp $string;
print join( "\n", split( /(.{80})/, $string ) ), "\n";

      [download]
[reply]
[d/l]
        Sorry. For a drop in replacement, you can use: 
        chomp;
print join( "\n", split( /(.{80})/ ) ), "\n";

        [download]
[reply]
[d/l]
(tye)Re: how do I line-wrap while copying a file to stdout?
by tye (Sage) on Apr 20, 2001 at 19:53 UTC

    Since it is a web page, I suspect I would like your interface much better if you, instead of wrapping lines at what you think is a good width, you let me and my browser pick a good width and wrap the stuff ourselves.

    For example, by encoding HTML entities and turning multiple newlines into <p /> and/or newlines into <br />.

            - tye (but my friends call me "Tye")
[reply]
[d/l]
[select]
Re: how do I line-wrap while copying a file to stdout?
by busunsl (Vicar) on Apr 20, 2001 at 11:22 UTC
    Try:

    print join "\n", unpack("A80" x (length($l) / 80 + 1), $l);

    [download]
[reply]
[d/l]
      this seems to be missing one newline per group of lines. And lines short than 80 characters also print, missing the newline.
      -allan
[reply]

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