Can't find error "Global symbol #xx requires explicit package name" - perl

Question

I have checked the questions that may already have an answer and none of them have helped.
This is for my semester project for Unix Programming. I have created a script that compares HTML files to one other from a website.
The script worked perfectly as expected until I tried to implement the second website, so in turn I deleted the added code for the second website and now I get the errors
Global symbol "#master" requires explicit package name
Global symbol "#child" requires explicit package name
within the csite_md5 subroutine. I have gone through the code many times over and cannot see the problem.
I am looking for another set of eyes to see if I'm just missing something simple, which usually is the case.
Also I am new to Perl as this is my first time using the language.
#!/usr/bin/perl
use strict;
use warnings;
use Digest::MD5 qw(md5_hex);
use File::Basename;
# Path to the c-site download root directory
my $csite_dir = '/root/websites/c-site/wget/';
opendir my $dh, $csite_dir or die $!;
# Finds the sub directories c-site_'date +%F' where the c-site download is located
my #wget_subdir_csite = sort grep /^[^.]/, readdir $dh;
# Creates the absolute path to the c-site download
my $csite_master_dir = "$csite_dir$wget_subdir_csite[0]/dayzunderground.webs.com";
my $csite_child_dir = "$csite_dir$wget_subdir_csite[1]/dayzunderground.webs.com";
# Call to subroutine to append the .html file name to the absolute path
my #master_csite = &gethtml_master_csite($csite_master_dir);
my #child_csite = &gethtml_child_csite($csite_child_dir);
&csite_md5(\#master_csite, \#child_csite);
sub gethtml_master_csite{
my ($master_path) = #_;
opendir (DIR, $master_path) or die $!;
# Ends with .html and is a file
my #html_master = sort grep {m/\.html$/i && -f "$master_path/$_"} readdir(DIR);
my #files_master = ("$master_path/$html_master[0]","$master_path/$html_master[1]","$master_path/$html_master[2]","$master_path/$html_master[3]");
return #files_master
}
sub gethtml_child_csite{
my ($child_path) = #_;
opendir (DIR, $child_path) or die $!;
# Ends with .html and is a file
my #html_child = sort grep {m/\.html$/i && -f "$child_path/$_"} readdir(DIR);
my #files_child = ("$child_path/$html_child[0]","$child_path/$html_child[1]","$child_path/$html_child[2]","$child_path/$html_child[3]");
return #files_child
}
sub csite_md5{
my ($master, $child) = #_;
if(&md5sum($master[0]) ne &md5sum($child[0])){
my $filename = basename($master[0]);
system("diff -u -d -t --width=100 $master[0] $child[0] > ~/websites/c-site/diff/c-site-$filename-`date +%F`");
#print "1"
}
if(&md5sum($master[1]) ne &md5sum($child[1])){
my $filename2 = basename($master[1]);
system("diff -u -d -t --width=100 $master[1] $child[1] > ~/websites/c-site/diff/c-site-$filename2-`date +%F`");
#print "2"
}
if(&md5sum($master[2]) ne &md5sum($child[2])){
my $filename3 = basename($master[2]);
system("diff -u -d -t --width=100 $master[2] $child[2] > ~/websites/c-site/diff/c-site-$filename3-`date +%F`");
#print "3"
}
if(&md5sum($master[3]) ne &md5sum($child[3])){
my $filename4 = basename($master[3]);
system("diff -u -d -t --width=100 $master[3] $child[3] > ~/websites/c-site/diff/c-site-$filename4-`date +%F`");
#print "4"
}
}
sub md5sum{
my $file = shift;
my $digest = "";
eval{
open(FILE, $file) or die "Can't find file $file\n";
my $ctx = Digest::MD5->new;
$ctx->addfile(*FILE);
$digest = $ctx->hexdigest;
close(FILE);
};
if($#){
print $#;
return "";
}
return $digest
}

Answer 1

$master and $child are array references; use them like $master->[0]. $master[0] uses the array #master, which is a completely separate variable.

Answer 2

I thought it may help to go through your program and point out some practices that are less than optimal
You shouldn't use an ampersand & when calling a Perl subroutine. That was required in Perl 4 which was superseded about 22 years ago
It is preferable to use the File::Spec module to manipulate file paths, both to handle cases like multiple path separators and for portability. File::Spec will also do the job of File::BaseName
It is unnecessary to use the shell to create a date string. Use the Time::Piece module and localtime->ymd generates the same string as date +%F
It is neater and more concise to use map where appropriate instead of writing multiple identical assignments
The gethtml_master_csite and gethtml_child_csite subroutines are identical except that they use different variable names internally. They can be replaced by a single gethtml_csite subroutine
You should use lexical file and directory handles throughout, as you have done with the first opendir. You should also use the three-parameter form of open (with the open mode as the second parameter)
If an open fails then you should include the variable $! in the die string so that you know why it failed. Also, if you end the string with a newline then Perl won't append the source file and line number to the string when it is printed
As you have read, the csite_md5 attempts to use arrays #master and #child which don't exist. You have array references $master and $child instead. Also, the subroutine lends itself to a loop structure instead of writing the four comparisons explicitly
In md5sum you have used an eval to catch the die when the open call fails. It is nicer to check for this explicitly
The standard way of returning a false value from a subroutine is a bare return. If you return '' then it will evaluate as true in list context
With those chnages in place your code looks like this. Please ask if you have any problem understanding it. Note that I haven't been able to test it but it does compile
#!/usr/bin/perl
use strict;
use warnings;
use Digest::MD5 qw(md5_hex);
use File::Spec::Functions qw/ catdir catfile splitpath /;
use Time::Piece 'localtime';
my $csite_dir = '/root/websites/c-site/wget/';
opendir my $dh, $csite_dir or die qq{Unable to open "$csite_dir": $!};
my #wget_subdir_csite = sort grep /^[^.]/, readdir $dh;
my ($csite_master_dir, $csite_child_dir) = map
catdir($csite_dir, $_, 'dayzunderground.webs.com'),
#wget_subdir_csite[0,1];
my #master_csite = gethtml_csite($csite_master_dir);
my #child_csite = gethtml_csite($csite_child_dir);
csite_md5(\#master_csite, \#child_csite);
sub gethtml_csite {
my ($path) = #_;
opendir my $dh, $path or die qq{Unable to open "$path": $!};
my #files = sort grep { /\.html$/i and -f } map catfile($path, $_), readdir $dh;
return #files;
}
sub csite_md5 {
my ($master_list, $child_list) = #_;
for my $i ( 0 .. $#$master_list ) {
my ($master, $child) = ($master_list->[$i], $child_list->[$i]);
if ( md5sum($master) ne md5sum($child) ) {
my $filename = (splitpath($master))[-1]; # Returns (volume, path, file)
my $date = localtime->ymd;
system("diff -u -d -t --width=100 $master $child > ~/websites/c-site/diff/c-site-$filename-$date");
}
}
}
sub md5sum {
my ($file) = #_;
my $digest = "";
open my $fh, '<', $file or do {
warn qq{Can't open file "$file": $!}; # '
return;
};
my $ctx = Digest::MD5->new;
$ctx->addfile($fh);
return $ctx->hexdigest;
}