Perl %{$var} 与 %$var

Question

%{$var} 和 %$var 有什么区别？我尝试了这段代码，但出现错误:

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";
    }
}

但是这段代码工作正常:

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

使用 %$HoH{$i} 可以创建 $HoH 的哈希引用，而使用 %{$HoH{$i}} 则可以创建哈希引用$HoH{$i}，这就是您想要的...并且，在您的代码上使用 strict :-)