It's

  delete $hoh{item2};

not

  delete $hoh{$item2};

and it does do what you request - it deletes the key "item2" from the top-level hash.

Hello brassbin,

smls++ has answered your question, but it occurs to me: if you don’t have a variable named $item2, either use strict or use warnings would have shown the error. With warnings:

Name "main::item2" used only once: possible typo at...
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and with strict:

Global symbol "$item2" requires explicit package name at...
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Moral: Always begin each script with:

use strict;
use warnings;
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It’s often useful to have:

use diagnostics;
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as well, to clarify any warnings or error messages.

Hope that helps,

thank you both! but i just realized something, i actually meant to say i used the "delete" call this way

$a = "item2";
delete $hoh{$a};
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it deleted the sub-level hash but not the key "item2" itself

Please post a piece of code that demonstrates the problem, including expected result and actual result. I could not reproduce the issue from your problem description.

use Data::Dumper;
%hoh = (
    'item1' =>  {
                       'key1' => '1',
                       'key2' => '1',
                       'key3' => '0'
                   },
    'item2' =>  {
                       'key1' => '0',
                       'key2' => '1'
                   }
);

print "Before delete:\n";
print Dumper \%hoh;

my $a = "item2";
delete $hoh{$a};

print "\n\nAfter delete:\n";
print Dumper \%hoh;
print "$a deleted!" if not exists $hoh{$a};
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Before delete:
$VAR1 = {
          'item1' => {
                       'key2' => '1',
                       'key1' => '1',
                       'key3' => '0'
                     },
          'item2' => {
                       'key2' => '1',
                       'key1' => '0'
                     }
        };


After delete:
$VAR1 = {
          'item1' => {
                       'key2' => '1',
                       'key1' => '1',
                       'key3' => '0'
                     }
        };
item2 deleted!
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That being said, you should abstain from using $a and $b as variables, as they have special meaning to the sort function.

thanks for pointing that out, i think i know now where the problem is

i was using a simplified code snippet to highlight the top-level key deletion question, the actual code is a bit more complicated, the variable that holds the top-level key is the result of a regular expression match, and i yet again underestimated the greediness of the .* construct

thanks again for pointing out the useful of "warnings" & "diagnostics" pragmas, and your help on the usage of the "delete" function in the HoH context, thank you all