[英]help understanding perl hash
Perl newbie here...I had help with this working perl script with some HASH code and I just need help understanding that code and if it could be written in a way that I would understand the use of HASHES more easily or visually?? 这里的Perl新手...我在使用一些HASH代码的Perl脚本中获得了帮助,我只需要帮助理解该代码,以及是否可以以更容易或更直观地理解HASHES的使用方式来编写它?
In summary the script does a regex to filter on date and the rest of the regex will pull data related to that date. 总之,脚本会执行一个正则表达式以按日期进行过滤,而其余的正则表达式将提取与该日期相关的数据。
use strict;
use warnings;
use constant debug => 0;
my $mon = 'Jul';
my $day = 28;
my $year = 2010;
my %items = ();
while (my $line = <>)
{
chomp $line;
print "Line: $line\n" if debug;
if ($line =~ m/(.* $mon $day) \d{2}:\d{2}:\d{2} $year: ([a-zA-Z0-9._]*):.*/)
{
print "### Scan\n" if debug;
my $date = $1;
my $set = $2;
print "$date ($set): " if debug;
$items{$set}->{'a-logdate'} = $date;
$items{$set}->{'a-dataset'} = $set;
if ($line =~ m/(ERROR|backup-date|backup-size|backup-time|backup-status)[:=](.+)/)
{
my $key = $1;
my $val = $2;
$items{$set}->{$key} = $val;
print "$key=$val\n" if debug;
}
}
}
print "### Verify\n";
for my $set (sort keys %items)
{
print "Set: $set\n";
my %info = %{$items{$set}};
for my $key (sort keys %info)
{
printf "%s=%s;", $key, $info{$key};
}
print "\n";
}
What I am trying to understand is these lines: 我想了解的是以下几行:
$items{$set}->{'a-logdate'} = $date;
$items{$set}->{'a-dataset'} = $set;
And again couple lines down: 再往下排几行:
$items{$set}->{$key} = $val;
Is this an example of hash reference? 这是哈希引用的示例吗? hash of hashes?
哈希哈希?
I guess i'm confused with the use of {$set} :-( 我想我对{$ set}的使用感到困惑:-(
%items
is a hash of hash references (conceptually, a hash of hashes). %items
是哈希引用的哈希(概念上是哈希的哈希)。 $set
is the key into %items
and then you get back another hash, which is being added to with keys 'a-logdate'
and 'a-dataset'
. $set
是%items
的键,然后您获得另一个哈希,该哈希将通过键'a-logdate'
和'a-dataset'
添加到其中。
(corrected based on comments) (根据评论更正)
Lou Franco's answer is close, with one minor typographical error—the hash of hash references is %items
, not $items
. Lou Franco的答案很接近,只有一个小的印刷错误-哈希引用的哈希值是
%items
,而不是$items
。 It is referred to as $items{key}
when you are retrieving a value from %items
because the value you are retrieving is a scalar (in this case, a hash reference), but $items
would be a different variable. 当您从
%items
检索值时,它称为$items{key}
因为您要检索的值是标量(在这种情况下为哈希引用),但是$items
是一个不同的变量。
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