如何在Perl中初始化2D数组？

How do I initialize a 2D array in Perl?

如何在Perl中初始化2D数组？

I am trying the following code:

我正在尝试以下代码：

 0 use strict;
10 my @frame_events = (((1) x 10), ((1) x 10));
20 print "$frame_events[1][1]\n";

but it gives the following error:

但它给出以下错误：

Can't use string ("1") as an ARRAY ref while "strict refs" in use at ./dyn_pf.pl line 20.

在./dyn_pf.pl第20行使用“strict refs”时，不能使用字符串（“1”）作为ARRAY引用。

This syntax only seems to initialize a 1D array as print "$frame_events[1]\n" works. Though Perl doesn't give any error during the assignment.

这种语法似乎只是初始化一维数组，因为打印“$ frame_events [1] \ n”有效。虽然Perl在分配期间没有给出任何错误。

4 个解决方案

#1

You cannot have an array of arrays in Perl, only an array of references to arrays.

你不能在Perl中有一个数组数组，只有一个数组引用数组。

my @frame_events = ([(1) x 10], [(1) x 10]);
print "$frame_events[1]->[1]\n";

Special case: you are free to omit the pointer dereferencing arrow between adjacent brackets (whether square or curly):

特殊情况：您可以省略相邻括号之间的指针解引用箭头（无论是方形还是卷曲）：

print "$frame_events[1][1]\n";

In general you cannot have:

一般来说，你不能有：

• arrays of arrays (of arrays ...)
• 数组数组（数组......）
• arrays of hashes (of ...)
• 哈希数组（......）
• hashes of arrays
• 数组哈希
• hashes of hashes.
• 哈希的哈希。

You can have:

你可以有：

• arrays of references to arrays (of references to arrays ...)
• 对数组的引用数组（对数组的引用...）
• arrays of references to hashes (of references to ...)
• 哈希引用数组（引用...）
• hashes of references to arrays
• 数组引用的哈希值
• hashes of references to hashes
• 散列哈希的哈希

You can also have:

你也可以：

• arrays of scalars
• 标量数组
• arrays of references of arrays of scalars
• 标量数组的引用数组
• arrays of references of arrays of references of arrays of scalars
• 标量数组引用数组的引用数组
• arrays of references of hashes of scalars
• 标量散列的引用数组
• etc.
• 等等

#2

See also Array of Arrays in Perl Data Structures Cookbook.

另请参见Perl Data Structures Cookbook中的数组数组。

#3

In Perl an array with two arrays in it get merged into a single array. You want references for the internal arrays if you don't want them concatenated. Here's a dump of your code:

在Perl中，一个包含两个数组的数组将合并为一个数组。如果不希望它们连接，您需要内部数组的引用。这是你的代码转储：

use strict;
use Data::Dumper;
my @frame_events = (((1) x 10), ((1) x 10));
print Dumper(\@frame_events);

result:

结果：

$VAR1 = [
          1,
          1,
          1,
          1,
          1,
          1,
          1,
          1,
          1,
          1,
          1,
          1,
          1,
          1,
          1,
          1,
          1,
          1,
          1,
          1
        ];

and if you switch to array reference creators, brackets instead of parents, with this code:

如果您使用以下代码切换到数组引用创建者，括号而不是父项：

use strict;
use Data::Dumper;
my @frame_events = ([(1) x 10], [(1) x 10]);
print Dumper(\@frame_events);

you get this:

你得到这个：

$VAR1 = [
          [
            1,
            1,
            1,
            1,
            1,
            1,
            1,
            1,
            1,
            1
          ],
          [
            1,
            1,
            1,
            1,
            1,
            1,
            1,
            1,
            1,
            1
          ]
        ];

#4

The quickest way is to use the push command.

最快的方法是使用push命令。

$size = 10; push @matrix, [(0)x$size] for (0..$size);

$ size = 10;推@matrix，[（0）x $ size]为（0 .. $ size）;

This will create a 10x10 array initialized with zeros.

这将创建一个用零初始化的10x10数组。