Perl Dereferencing Syntax

问题

What is the syntax to dereference a reference in Perl?

回答1:

                              Direct           Using References     Using References
                                               Circumfix Syntax^[1]Postfix Syntax

scalar  itself                $s               ${$sr}               $sr->$* ^[3]array   itself                @a               @{$ar}               $ar->@* ^[3]array   element               $a[0]            ${$ar}[0]            $ar->[0]
array   slice                 @a[0,1,2]        @{$ar}[0,1,2]        $ar->@[0,1,2] ^[3]array   index/value slice^[2]   %a[0,1,2]        %{$ar}[0,1,2]        $ar->%[0,1,2] ^[3]array   last index            $#a              $#{$ar}              $ar->$#* ^[3]hash    itself                %h               %{$hr}               $hr->%* ^[3]hash    element               $h{'a'}          ${$hr}{'a'}          $hr->{'a'}
hash    slice                 @h{'a','b','c'}  @{$hr}{'a','b','c'}  $hr->@{'a','b','c'} ^[3]hash    key/value slice^[2]     %h{'a','b','c'}  %{$hr}{'a','b','c'}  $hr->%{'a','b','c'} ^[3]code    call                  func(@args)
code    w/ prototype ignored  &func(@args)     &{$cr}(@args)        $cr->(@args)
code    w/ inherited @_       &func            &{$cr}               $cr->&* ^[3]glob    itself                *glob            *{$gr}               $gr->** ^[3]glob    slot                  *glob{ARRAY}     *{$gr}{ARRAY}        $gr->*{ARRAY} ^[3]

Notes:

The curly brackets around $sr, $ar, $hr, $cr and $gr are optional when the contents of the curlies is simply a scalar.

If they are used, those curlies form blocks, so they can actually contain multiple statements.
Requires Perl 5.20+.
Requires Perl 5.24+. Available in Perl 5.20+ by adding both use feature qw( postderef ); and no warnings qw( experimental::postderef );, or by adding use experimental qw( postderef );.