Preventing Blank Lines Between Printed Array Elements

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

Hi Monks, I'm new to coding and I'm probably missing something obvious. I'm writing a script to place Markdown footer links under their respective paragraphs. So a file that looks like this:

This is a an example of [Markdown][1] footer links. I'm trying to use 
+[Perl][2] to organize them more coherently.

But I'm getting too many newlines and I'm hoping the [PerlMonks][3] ca
+n help.

[1]: https://daringfireball.net/projects/markdown/
[2]: http://www.perl.org/
[3]: http://www.perlmonks.org/
[download]

Should look like this:

This is a an example of [Markdown][1] footer links. I'm trying to use 
+[Perl][2] to organize them more coherently.

[1]: https://daringfireball.net/projects/markdown/
[2]: http://www.perl.org/

But I'm getting too many newlines and I'm hoping the [PerlMonks][3] ca
+n help.

[3]: http://www.perlmonks.org/
[download]

I want blank lines before and after each block of footer links, but instead, it's placing newlines between each array element, like this:

This is a an example of [Markdown][1] footer links. I'm trying to use 
+[Perl][2] to organize them more coherently.

[1]: https://daringfireball.net/projects/markdown/

[2]: http://www.perl.org/

But I'm getting too many newlines and I'm hoping the [PerlMonks][3] ca
+n help.

[3]: http://www.perlmonks.org/
[download]

Here's the code I'm using:

#!/usr/bin/perl 

use strict;
use warnings;
use diagnostics;

my $text;
local $/;
$text = <>;

my @url_list = ($text =~ m/\[.*?\]\:.*/g);

$text =~ s/\s+\[.*?\]\:.*//g;

foreach my $line (split /^/, $text) {
    print $line;
    foreach ($line =~ m/\[.*?\]\[(.*?)\]/g) {
        my $link_number = $_;
         print "\n";
        print grep(/(\[$link_number\]\:.*)/, @url_list);
        print "\n";
    }
}
[download]

I've tried chomp on all the relevant variables.

Comment on Preventing Blank Lines Between Printed Array Elements Select or Download Code

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Re: Preventing Blank Lines Between Printed Array Elements by NetWallah (Canon) on May 05, 2014 at 05:26 UTC
This small modification makes your code work: `foreach my $line (split /^/, $text) { print $line; my $separator_printed = 0; foreach ($line =~ m/\[.?\]\[(.?)\]/g) { my $link_number = $_; $separator_printed++ or print "\n"; print grep(/(\[$link_number\]\:.*)/, @url_list); print "\n"; } }` [download] What is the sound of Perl? Is it not the sound of a wall that people have stopped banging their heads against? -Larry Wall, 1992	[reply] [d/l]
Re^2: Preventing Blank Lines Between Printed Array Elements by immamanatee (Initiate) on May 05, 2014 at 16:49 UTC
Thanks NetWallah, that works perfectly.	[reply]
Re: Preventing Blank Lines Between Printed Array Elements by kcott (Archbishop) on May 05, 2014 at 07:11 UTC
G'day immamanatee, Welcome to the monastery. You're reading your data an inordinate amount of times: Read all input into `$text` using slurp mode (`$/ = undef`). Read all data to generate `@url_list`. Read all data to remove URL lines. Read all remaining lines in an outer loop. Read each line in an inner loop to generate link numbers. Read the entire `@url_list` in every pass through the inner loop. As you're dealing with paragraphs, consider reading your input as paragraphs and processing it just once: Read all input into an array using paragraph mode (`$/ = ''`). Create a hash, mapping link number to URL, using just the last paragraph of text. Loop through all but the last paragraph, printing each paragraph and any associated footnotes. Here's an example using your data: #!/usr/bin/env perl -l use strict; use warnings; my @data = do { local $/ = ''; <DATA> }; my %urls = map { /^\[(\d+)/ => $_ } split /^/ => $data[-1]; print $data[$_], @urls{$data[$_] =~ /\[.*?\]\[(\d+)\]/g} for 0 .. $#da +ta - 1; __DATA__ This is a an example of [Markdown][1] footer links. I'm trying to use +[Perl][2] to organize them more coherently. But I'm getting too many newlines and I'm hoping the [PerlMonks][3] ca +n help. [1]: https://daringfireball.net/projects/markdown/ [2]: http://www.perl.org/ [3]: http://www.perlmonks.org/ [download] Output: `This is a an example of [Markdown][1] footer links. I'm trying to use +[Perl][2] to organize them more coherently. [1]: https://daringfireball.net/projects/markdown/ [2]: http://www.perl.org/ But I'm getting too many newlines and I'm hoping the [PerlMonks][3] ca +n help. [3]: http://www.perlmonks.org/` [download] -- Ken	[reply] [d/l] [select]
Re^2: Preventing Blank Lines Between Printed Array Elements by immamanatee (Initiate) on May 05, 2014 at 16:52 UTC
Thanks Ken. My current sloppy code works OK, as the files are small, but I'll study your solution for the future.	[reply]