打印哈希键时出现 Perl 奇怪的结果

Question

my $dat;
$dat{"1","1","1","1","1"}{'CR'} = "2";

foreach my $k1 (keys %dat){
    print $k1;
}

这是我的代码，应该没问题，可以在其他电脑上执行，但我的笔记本电脑显示这个结果

它编译没有错误.....有人能告诉我发生了什么吗？是不是不太确定模块？

Answer 1

您可能需要查看 perlvar

$; The subscript separator for multidimensional array emulation. If you refer to a hash element as
$foo{$a,$b,$c}
it really means
$foo{join($;, $a, $b, $c)}

默认为4，与awk中的SUBSEP相同。如果您的密钥包含二进制数据，则 $;.

可能没有任何安全值

use strict;
use warnings;

my %dat;
$dat{"1","1","1","1","1"}{'CR'} = "2";
# which is equivalent to
# my $k = join($;, "1","1","1","1","1");
# $dat{$k}{'CR'} = "2";

foreach my $k1 (keys %dat){
    print "$_\n" for map { $_ eq $; ? '$;' : $_ } split //, $k1;
}

输出

1
$;
1
$;
1
$;
1
$;
1

Answer 2

您的散列不包含您认为的内容。具体来说，它只有一个键：

#!/usr/bin/env perl    

use strict;
use warnings;

my %dat;
$dat{"1","1","1","1","1"}{'CR'} = "2";

use Data::Dumper; 
print Dumper \%dat

输出：

$VAR1 = {
          '11111' => {
                           'CR' => '2'
                         }
        };

正如 Сухой27 所建议的那样，键中的 1 是使用 $; 的值作为分隔符连接起来的：

#!/usr/bin/env perl    

use strict;
use warnings;

$; = '---';

my %dat;
$dat{"1","1","1","1","1"}{'CR'} = "2";

use Data::Dumper; 
print Dumper \%dat

输出：

$VAR1 = {
          '1---1---1---1---1' => {
                                   'CR' => '2'
                                 }
        };

将 $; 更改为空字符串，您将得到 11111 作为输出，正如我假设的那样。

打印哈希键时出现 Perl 奇怪的结果

Perl weird result when printing hash key

perl

hash

key