$VAR1 = [
          'test.xls',
          'test-2.xls',
          'test-3.xls'
        ];

##</code><code>##

#!/usr/bin/perl
use strict;
use warnings;
use Getopt::Long();

sub usage {
    my $message = shift(@_);
    if (defined $message && length $message) {
	$message .= "\n"
	    unless $message =~ /\n$/;
    }

    my $command = $0;
    $command =~ s#^.*/##;

    print STDERR (
	$message,
	"usage: $command -f file(s).xls -p file.csv\n"
	);

    die("\n")
}

my @xls;
my $csv;

print "This is the number of \@ARGV arguments before the process ".@ARGV."\n";

Getopt::Long::GetOptions(
    'f=s{1,}' => sub {
	foreach $_ (@_) {
	    print $_ . "\n";
	    /\.xls$/
		or die ("Invalid format for option expected -f '*.xls'\n");
	    push(@xls,$_);
	}
    },
    'p=s'     => sub {
	$_ = pop @_;
	/\.csv$/
	    or die ("Invalid format for option expected -p '*.csv'\n");
	$csv = $_;
    }
    )
    or usage("Invalid commmand line options.");

usage("The '*.xls' file(s) needs to be specified.")
    if scalar (@xls == 0);

usage("The '*.csv' file needs to be specified.")
    unless defined $csv;

print "Input given form \@xls: ".@xls."\n";
print "Input given form \$csv: ".$csv."\n";

=test
    'f=s{1,}' => sub {
	foreach $_ (@_) {
	    print $_ . "\n";
	    /\.xls$/
		or die ("Invalid format for option expected -p '*.xls'\n");
=cut

##</code><code>##

This is the number of @ARGV arguments before the process 4
f
Invalid format for option expected -f '*.xls'
Invalid commmand line options.
usage: long.pl -f file(s).xls -p file.csv

##</code><code>##

Getopt::Long::GetOptions(
    'f=s{1,}' => sub {
	foreach $_ (@_) {
	    if ($_ =~ /\.xls$/) {
		print "This is if \$_: ".$_."\n";
		push( @xls , $_ );
	    }
	    elsif ($_ =~ /^f/) {
		next;
	    }
	    else {
		die ("Invalid format for option expected -f '*.xls'\n");
	    }
	} # End of foreach
    },
    'p=s'     => sub {
	$_ = pop @_;
	/\.csv$/
	    or die ("Invalid format for option expected -p '*.csv'\n");
	$csv = $_;
    }
    )
    or usage("Invalid commmand line options.");