Perl 如何从数组的散列中检索数组? [英] Perl How do I retrieve an array from a hash of arrays?

问题描述

我对 Perl 还很陌生，所以如果这似乎是一个简单的问题，请原谅我...

I'm fairly new to Perl, so forgive me if this seems like a simple question...

无论如何，我有一个数组散列，我正在尝试检索散列中的一个数组，但我所能得到的只是数组的标量大小.

Anyway, I have a hash of arrays and I'm trying to retrieve one of the arrays in the hash, but all I can get is the scalar size of the array.

%HoA = a hash of arrays
$key = some key in the hash

foreach $nextItem (@HoA{$key}) {
  do a bunch of stuff with $nextItem
}

当我这样做时，$nextItem 总是只是数组的大小并且循环只运行一次.我试过打印以下内容:

When I do this, $nextItem is always just the size of the array and the loop only runs through one time. I've tried printing the following:

@HoA{$key}
$HoA{$key}
@$HoA{$key}

前两个给了我标量大小，第三个给了我什么......我在这里错过了什么?

The first two give me the scalar size and the third gives me nothing...what am I missing here?

更新:我想知道我的问题是否真的是我将数组添加到散列的方式.这是我正在做的:

UPDATE: I'm wondering if my problem is actually the way I'm adding the arrays to the hash. Here's what I'm doing:

@HoA{$key} = split(/ /, $list);

这是将数组粘贴在哈希中，还是将数组大小粘贴在哈希中?

Does that stick the array in the hash, or the array size in the hash?

更新 2:我尝试了以下代码块:

UPDATE 2: I tried the following block of code:

my $key = "TEST";
my %HoA = ();
my @testarray = (1, 2, 3);
@HoA{$key} = @testarray;
print Dumper(%HoA);

输出如下:

$VAR1 = 'TEST';
$VAR2 = 1;

为什么只贴数组的第一个值?

Why is it only sticking the first value of the array in?

推荐答案

尝试以这种方式引用您的数组:

Try referencing your array this way:

%HoA = a hash of arrays
$key = some key in the hash

foreach $nextItem (@{$HoA{$key}}) {
  do a bunch of stuff with $nextItem
}

您在 $HoA{$key} 处获取数组引用并将其设为数组.

You take the array reference at $HoA{$key} and make it an array.

对于你的更新，我认为你会得到你想要的，如果你这样做:

For your update, I think you will get what you want, if you do it this way:

@{$HoA{$key}} = split(/ /, $list);

或者你可以做

push(@{$HoA{$key}}, split(/ /, $list);

例如:

my $list = "fred joe brown sam";
my %HoA = ();
my $key = "jacob";
@{$HoA{$key} = split(/ /, $list);
foreach my $item (@{$HoA{$key}})
{
    print "Test item: $nextItem\n";
}

You will get:
Test item: fred
Test item: joe
Test item: brown
Test item: sam

将 use strict; 添加到程序的顶部.基本上，当您定义了散列时，您试图将 HoA 用作数组.您不正确地引用了哈希的内容.为了正确地做到这一点，你真的需要在 @ 和 HoA 之间有一个 $.Perl 是无类型的，如果你不use strict;，它会让你逍遥法外.来自oreilly的参考摘录可能会澄清一些问题.

Add use strict; to the top of your program. Basically you are attempting to use HoA as an array when you have a hash defined. You are referencing the contents of your hash improperly. To do it properly you really really need to have a $ between the @ and HoA. Perl is typeless and will let you get away with murder if you don't use strict;. A reference excerpt from oreilly might clear a few things up.

my @testarray 是一个数组
我的 %hash 是一个哈希值
$hash{$el1} = \@array 是一个哈希元素，它的值是一个数组的引用
@{$hash{$el1}} = @array 是一个包含数组的哈希元素

my @testarray is an array
my %hash is a hash
$hash{$el1} = \@array is a hash element that has the value of a ref to an array
@{$hash{$el1}} = @array is a hash element that contains an array

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