First of all, the notation
%hash = { ... is wrong. You either assign a hash with
%hash = ( ... or a hash
reference with
$hash = { .... Watch those parentheses and curly braces. See
perlreftut and
perlref for more information.
As for deleting:
#!/usr/bin/perl
use Data::Dumper;
$hash = {
abc => {
'def' => 1,
},
ghi => {
jkl => 1,
mno => 1,
},
};
print Dumper(\$hash);
delete($hash->{abc}->{def});
print Dumper(\$hash);
__END__
$VAR1 = \{
'abc' => {
'def' => 1
},
'ghi' => {
'mno' => 1,
'jkl' => 1
}
};
$VAR1 = \{
'abc' => {},
'ghi' => {
'mno' => 1,
'jkl' => 1
}
};
The second question: I don't know :-). Having an undefined hash value is perfectly valid, so the upper level is not automatically deleted when the lower level becomes undefined. You could add a statement like
delete $hash->{$key} if not keys %{$hash->{$key}}. This deletes the key only if the hash it references is empty.
Arjen
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