use strict;
use warnings;
use Data::Dumper;

my $i=0;
my %hARGV = map {
  if (/^--(\w+)=(\w+)$/) {

    # option => value
    $1 => $2;

  } elsif (/^--(\w+)$/) {

    # flag => 1
    $1 => 1

  } elsif (m{^[\w/]}) {

    # filename => fileorder
    $_ => $i++;

  } else {

    # bad argument - add nothing to the result hash
    warn "Invalid option: <$_> - options must begin with "
      ."-- or be a legal file name";
    ();

  }
} @ARGV;
print Dumper(\%hARGV);

##</code><code>##

use strict;
use warnings;
use Data::Dumper;

my @aFiles;  # <== array instead of my $i
my %hARGV = map {
  if (/^--(\w+)=(\w+)$/) {
    # option => value
    $1 => $2;
  } elsif (/^--(\w+)/) {
    # flag => 1
    $1 => 1
  } elsif (m{^[\w/]}) {

     push @aFiles, $_; # <== put filenames into an array
     ();          # <== don't put anything into hash (yet)

  } else {
    # bad argument - add nothing to the result hash
    warn "Invalid option: <$_> - options must begin with "
      ."-- or be a legal file name";
    ();
  }
} @ARGV;
$hARGV{files}=\@aFiles if @aFiles; # <== _now_ put the files in the hash

print Dumper(\%hARGV);

##</code><code>##

use strict;
use warnings;
use Data::Dumper;

sub processArgs {
  my ($sArg, $aFiles) = @_;

  if ($sArg =~ /^--(\w+)=(\w+)$/) {
    # option => value
    $1 => $2;
  } elsif ($sArg =~ /^--(\w+)/) {
    # flag => 1
    $1 => 1
  } elsif ($sArg =~ m{^[\w/]}) {
    push @$aFiles, $_;
    ();
  } else {
    # bad argument - add nothing to the result hash
    warn "Invalid option: <$_> - options must begin with "
      ."-- or be a legal file name";
    ();
  }
}

my @aFiles;
my %hARGV = map { processArgs($_, \@aFiles) } @ARGV;
$hARGV{files}=\@aFiles if @aFiles;

print Dumper(\%hARGV);