Perl％{$ var} vs％$ var

Question

%{$var}和%$var之間的區別是什麼？我想這個代碼，但有錯誤：

each on reference is experimental at test.pl line 21. Type of argument to each on reference must be unblessed hashref or arrayref at test.pl line 21.

use feature 'say'; 

%HoH = (
    1 => { 
     husband => "fred", 
     pal  => "barney", 
    }, 
    2 => { 
     husband => "george", 
     wife  => "jane", 
     "his boy" => "elroy", 
    }, 
    3 => { 
     husband => "homer", 
     wife  => "marge", 
     kid  => "bart", 
    }, 
); 

for ($i = 1; $i <= 3; $i++) { 
    while (($family, $roles) = each %$HoH{$i}) { 
     say "$family: $roles"; 
    } 
} 

但這個代碼工作正常：

use feature 'say'; 

%HoH = (
    1 => { 
     husband => "fred", 
     pal  => "barney", 
    }, 
    2 => { 
     husband => "george", 
     wife  => "jane", 
     "his boy" => "elroy", 
    }, 
    3 => { 
     husband => "homer", 
     wife  => "marge", 
     kid  => "bart", 
    }, 
); 

for ($i = 1; $i <= 3; $i++) { 
    while (($family, $roles) = each %{$HoH{$i}}) { 
     say "$family: $roles"; 
    } 
} 

Answer 1

隨着%$HoH{$i}你做$斛散列引用，而與%{$HoH{$i}}你犯了一個哈希引用$HoH{$i}，這就是你想要的...而且，use strict對你的代碼:-)

Answer 2

由於解析的優先級不同哈希與下標散列。它適用於第二個版本 - %{ $HoH{$i} } - 因爲您明確指出$HoH{$i}查找返回的值本身就是一個hashref。

而%$HoH{$i}被解釋爲%{ $HoH }{$i} - 即。在將表達式$HoH解釋爲hashref之後發生下標 - 事實並非如此。 %HoH是一個散列，但不使用$HoH - 即未定義。