如何将元素推送到作为哈希值保存的数组引用中? [英] How can I push an element into an array reference held as a hash value?

问题描述

%data = (
    'digits' => [1, 2, 3],
    'letters' => ['a', 'b', 'c']
);

我怎样才能push '4' 到$data{'digits'}?

我是 Perl 的新手.那些 $、@、% 符号在我看来很奇怪；我来自 PHP 背景.

I am new to Perl. Those $, @, % symbols look weird to me; I come from a PHP background.

推荐答案

push @{ $data{'digits'} }, 4;

$data{'digits'} 返回一个数组引用.将 @{} 放在它周围以取消引用它".同样，%{} 将取消引用哈希引用，而 ${} 将取消引用标量引用.

$data{'digits'} returns an array-reference. Put @{} around it to "dereference it". In the same way, %{} will dereference a hash reference, and ${} a scalar reference.

如果您需要将某些内容放入散列引用中，即

If you need to put something into a hash reference, i.e.

$hashref = { "foo" => "bar" }

您可以使用:

${ $hashref }{ "foo2" } = "bar2"

或箭头符号:

$hashref->{"foo2"} = "bar2"

在某种程度上，将引用视为与变量名称相同的东西:

In a certain way, think of a reference as the same thing as the name of the variable:

push @{ $arrayref   }, 4
push @{ "arrayname" }, 4
push    @arrayname   , 4

事实上，这就是软引用".如果您没有开启所有严格性，您可以从字面上:

In fact, that's what "soft references" are. If you don't have all the strictnesses turned on, you can literally:

# perl -de 0
  DB<1> @a=(1,2,3)
  DB<2> $name="a"
  DB<3> push @{$name}, 4
  DB<4> p @a
1234

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