%load_number_hash = ();   # Deletes everything.
[download]

Abigail

Why there isn't any function in perl that deletes everything in a hash, removes keys, and deletes it such that it is like just it was declered

Either of the following will do it:

undef %hash;
%hash = ();
[download]

The error you gave doesn't make a lot of sense without some context.

use strict;
use warnings;

use Data::Dumper;

my @load_array = (0..9);

my %load_number_hash = ();
foreach(@load_array){
    $load_number_hash{$_} = $_;
}
print Dumper \%load_number_hash;

delete $load_number_hash{3};
print Dumper \%load_number_hash;

%load_number_hash = ();
print Dumper \%load_number_hash;
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$VAR1 = {
          '0' => 0,
          '1' => 1,
          '2' => 2,
          '3' => 3,
          '4' => 4,
          '5' => 5,
          '6' => 6,
          '7' => 7,
          '8' => 8,
          '9' => 9
        };
$VAR1 = {
          '0' => 0,
          '1' => 1,
          '2' => 2,
          '4' => 4,
          '5' => 5,
          '6' => 6,
          '7' => 7,
          '8' => 8,
          '9' => 9
        };
$VAR1 = {};
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use strict;
use warnings;
my @load_array = (1,2,3);
my %load_number_hash = ();
foreach(@load_array){
     $load_number_hash{$_} = $_;
}

%load_number_hash = ();
print $load_number_hash{1};
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artist

Try printing @load_array just before the loop, or the value of $_ just inside the loop. I bet that you have one or more undefs in there somewhere.

Quite how you got to asking this question from that error message I'm confused about. What did you think that error meant was happening?