I had some fun with numeric keys, then explored the surprising string 8 is NOT eq number 8, not realizing until much later the cause of this result: if ($string_eight eq $b).

After all, $string_eight and $numeric_eight are 'eq'. And, as I expected, the 'eq' operator causes stringification of the numeric value.

use strict;
use warnings;
use Data::Dumper;
use Devel::Peek;

my %hash = (
    1e2     => '100',
    100     => '100',
    0x64    => '100',
    0144    => '100',
);

print Dumper(\%hash);

my $string_eight = '8';
my $numeric_eight = 8;

print "\n\$numeric_eight before use with 'eq'\n";
Dump($numeric_eight);
if ($string_eight eq $numeric_eight) {
    print "'eq'\n";
} else {
    print "not 'eq'\n";
}
print "\n\$numeric_eight after use with 'eq'\n";
Dump($numeric_eight);

print "\n\$numeric_eight = $numeric_eight\n";
print "\n\$numeric_eight after use in a string (i.e. stringification)\
+n";
Dump($numeric_eight);

if ($string_eight eq $numeric_eight) {
    print "not 'eq'\n";
} else {
    print "'eq'\n";
}
print "\n\$string_eight then \$numeric_eight after all\n";
Dump($string_eight);
Dump($numeric_eight);
__END__
$VAR1 = {
          '100' => '100'
        };

$numeric_eight before use with 'eq'
SV = IV(0x97df82c) at 0x97df830
  REFCNT = 1
  FLAGS = (PADMY,IOK,pIOK)
  IV = 8
'eq'

$numeric_eight after use with 'eq'
SV = PVIV(0x97e01b8) at 0x97df830
  REFCNT = 1
  FLAGS = (PADMY,IOK,POK,pIOK,pPOK)     <-- note POK is now set
  IV = 8
  PV = 0x97ee168 "8"\0                  <-- and there is now a PV, CUR
+ and LEN as well as IV
  CUR = 1
  LEN = 4

$numeric_eight = 8

$numeric_eight after use in a string (i.e. stringification)
SV = PVIV(0x97e01b8) at 0x97df830
  REFCNT = 1
  FLAGS = (PADMY,IOK,POK,pIOK,pPOK)
  IV = 8
  PV = 0x97ee168 "8"\0
  CUR = 1
  LEN = 4
not 'eq'

$string_eight then $numeric_eight after all
SV = PV(0x98339d8) at 0x98736e8
  REFCNT = 1
  FLAGS = (PADMY,POK,pPOK)
  PV = 0x97e4ba0 "8"\0
  CUR = 1
  LEN = 4
SV = PVIV(0x97e01b8) at 0x97df830
  REFCNT = 1
  FLAGS = (PADMY,IOK,POK,pIOK,pPOK)
  IV = 8
  PV = 0x97ee168 "8"\0
  CUR = 1
  LEN = 4

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In reply to Re^3: Illegal octal digit error by ig
in thread Illegal octal digit error by lakshmananindia

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