如何在 Perl 中创建哈希的哈希？

Question

我是 Perl 新手。我需要在 Perl 中定义一个如下所示的数据结构：

  city 1 -> street 1 - [ name , no of house , senior people ]
            street 2 - [ name , no of house , senior people ]


  city 2 -> street 1 - [ name , no of house , senior people ]
            street 2 - [ name , no of house , senior people ]

我怎样才能实现这个？

Answer 1

这是使用哈希引用的另一个示例：

my $data = {
    city1 => {
        street1 => ['name', 'house no', 'senior people'],
        street2 => ['name','house no','senior people'],
    },
    city2 => {
        street1 => etc...
        ...
    }
};

然后您可以通过以下方式访问数据：

$data->{'city1'}{'street1'}[0];

或者：

my @street_data = @{$data->{'city1'}{'street1'}};
print @street_data;

Answer 2

答案

my %city ;

 $city{$c_name}{$street} = [ $name , $no_house , $senior];

我找到了可以用这种方式生成的

Answer 3

Perl 数据结构手册 perldsc 可能会有所帮助。它有示例向您展示如何创建通用数据结构。

Answer 4

my %city ;

如果你想推

push( @{ city{ $c_name } { $street } }, [ $name , $no_house , $senior] );

(0r)

push @{ city{ $c_name } { $street } }, [ $name , $no_house , $senior];

Answer 5

您可以在这个答案中阅读我的简短教程。简而言之，您可以将对哈希的引用放入值中。

%hash = ( name => 'value' );
%hash_of_hash = ( name => \%hash );
#OR
$hash_of_hash{ name } =  \%hash;


# NOTICE: {} for hash, and [] for array
%hash2 = ( of_hash => { of_array => [1,2,3] } );
#                  ---^          ---^
$hash2{ of_hash }{ of_array }[ 2 ]; # value is '3'
#     ^-- lack of -> because declared by % and ()


# same but with hash reference
# NOTICE: { } when declare
# NOTICE: ->  when access
$hash_ref = { of_hash => { of_array => [1,2,3] } };
#        ---^
$hash_ref->{ of_hash }{ of_array }[ 2 ]; # value is '3'
#     ---^