... I'm stuck ...

Write more functions, determine the common parts and turn them into functions, then turn the non-common parts into functions , so you have small functions you can understand 

#!/usr/bin/perl --
use strict;
use warnings;

Main( @ARGV );
exit( 0 );

sub Show_Red_HTML {
    my( $query )     = @_;
    my $dirname      = '.';
    my $js_includes  = js_includes();
    my $css_includes = stylesheet_includes();
    my $title        = "This is the redness";
    my $drops        = red_dropdown_files( $dirname );
    my $body         = red_form_html( $query, $drops );
    
    return Show_HTML( "$css_includes $js_includes", $title, $body );
} ## end sub Show_Red_HTML

sub Show_HTML {
    my( $head, $title, $body ) = @_;
    
    my $header = common_body_header_html();
    my $footer = common_body_footer_html();
    
    return qq{<!DOCTYPE html>
<html>
    <head>
        <title> $title </title>
        $head
    </head>
    <body>
    $header
    $body
    $footer
    </body>
</html>};

} ## end sub Show_HTML

sub red_dropdown_files {
    my( $dirname ) = @_;
    
    use Path::Tiny qw/ path cwd /;
    use CGI qw/ escapeHTML /;
    
    my @files = path( $dirname )->children;
    my $ret   = "";
    for my $file ( @files ) {
        $ret .= sprintf qq{<option value="%s">%s</option>\n},
          escapeHTML( $file ), escapeHTML( $file );
    }
    return $ret;
} ## end sub red_dropdown_files

[download]

Why write like this? Its easier to test/debug each small part seperately , for example 

sub Main {
    Tests();
#   RealProgram();
} ## end sub Main

sub Tests {
    require Test::More;
    Test::More->import( 'no_plan' );  ## and ok()...
    test_drops();
} ## end sub Tests

sub test_drops {
    chdir 'testdir';
    my $drops = red_dropdown_files( '.' );
    ok( int $drops =~ m{\Q<option value="chapter-8.pdf">\E}, 'drops wo
+rks' );
} ## end sub test_drops

[download]

Its important not to forget to escapeHTML

In reply to Re: HTML/CGI for loop problem by Anonymous Monk
in thread HTML/CGI for loop problem by Jabox

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.