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Is there a way to get a sub-hash? Do I need to use a hash slice?
For example:
%hash = ( a => 1, b => 2, c => 3 ); I want only
%hash = ( a => 1, b => 2 ); 
628
Perl Hash Accessing To access single element of hash, ($) sign is used before the variable name. And then key element is written inside {} braces.
my %h = ( secret => 1; );
print "$ perl_print_hash_variable{'-hash_key2'} \n"; Description: The Perl print hash can used $ symbol for a single hash key and its value. The Perl print hash can use the % symbol for multiple hash keys and their values.
It means a scalar value, as in $hash{key} and $array[$num]. In this case it's a scalar variable because it's a scalar value and there is no indexing chars after it.
Hash slices return the values associated with a list of keys. To get a hash slice you change the sigil to @ and provide a list of keys (in this case "a" and "b"):
my @items = @hash{"a", "b"}; Often you can use a quote word operator to produce the list:
my @items = @hash{qw/a b/}; You can also assign to a hash slice, so if you want a new hash that contains a subset of another hash you can say
my %new_hash; @new_hash{qw/a b/} = @hash{qw/a b/}; Many people will use a map instead of hash slices:
my %new_hash = map { $_ => $hash{$_} } qw/a b/; Starting with Perl 5.20.0, you can get the keys and the values in one step if you use the % sigil instead of the @ sigil:
my %new_hash = %hash{qw/a b/}; If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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