在Perl中,如何遍历由YAML加载的哈希数组？

Question

我将以下YAML流加载到Perl的数组中,我想遍历与Field2关联的数组.

use YAML;

my @arr = Load(<<'...');
---
Field1: F1
Field2:
 - {Key: v1, Val: v2}
 - {Key: v3, Val: v4}
---
Field1: F2
Field2:
 - {Key: v5, Val: v6}
 - {Key: v7, Val: v8}
...

foreach (@arr) {
    @tmp = $_->{'Field2'};   
    print $#tmp; # why it says 0 when I have 2 elements?

    # Also why does the below loop not work? 
    foreach ($_->{'Field2'}) {
    print $_->{'Key'} . " -> " $_->{'Val'} . "\n";
 }
}

我感谢任何反馈.谢谢.

Answer 1

因为您没有正确使用引用.你可能想重读perldoc perlreftut和perldoc perlref.

#!/usr/bin/perl

use strict;
use warnings;

use YAML;

my @arr = Load(<<'...');
---
Field1: F1
Field2:
 - {Key: v1, Val: v2}
 - {Key: v3, Val: v4}
---
Field1: F2
Field2:
 - {Key: v5, Val: v6}
 - {Key: v7, Val: v8}
...

for my $record (@arr) {
     print "$record->{Field1}:\n";
     for my $subrecord (@{$record->{Field2}}) {
         print "\t$subrecord->{Key} = $subrecord->{Val}\n";
     }
}