Question

我尝试迭代包含其他哈希的哈希。

我收到错误：

全局符号“％arch_”需要显式包名称

这是一段代码：

my %ARCH_CODES = (
    armv7  => {id  => 102, desc => "aaaaaa"},
    i386   => {id  => 103, desc => "bbbbbb"},
    x86_64 => {id  => 104, desc => "cccccc"},
    arm64  => {id  => 105, desc => "dddddd"}
);

sub af_exit
{
    my %_error = @_;
    writeLogAndPrint($_error{'id'});
    exit($_error{'id'});
}

所以我想在armv7，i386等循环中运行，然后将哈希映射发送到af_exit

for my $arch_ (keys %ARCH_CODES) {
       foo($ARCH_CODES{$arch_}); 
       # tried foo(%{ $ARCH_CODES{$arch_} } ) 
    }

问题发生在foo方法：

sub foo
{
   my %arch = @_; # here I get an ERROR: Global symbol "%arch_" requires explicit package name
     my $res = runCommand("file zzz | grep \"$arch{id})\"");
     af_exit($ARCH_CODES{$arch});
   }
}

第二个问题是af_exit应该收到哈希所以我需要以某种方式将$ARCH_CODES{$arch}转换为哈希而不是标量

我尝试与this answer: Perl:Access values of hash inside a hash类似但得到相同的错误

有什么想法吗？

Answer 1

函数foo正在获取hashref

foo( $ARCH_CODES{$arch_} );

因为%ARCH_CODES的值是哈希引用，而它需要哈希

sub foo
{
    my %arch = @_;
    # ...
}

因此，您尝试将具有单个标量（hashref）的列表分配给哈希。为此，如果您发出警告，则会收到警告Odd number of elements in hash assignment，这会直接导致您出错。

更改foo以便使用该标量

my ($rarch) = @_;

然后使用引用$rarch，或者在子my %arch = %$rarch中创建一个新哈希值，并保持函数代码的其余部分不变。

或者您可以将哈希值传递给函数foo( %{$ARCH_CODES{$arch_}} )，其余代码保持不变。一般来说，我更喜欢通过引用传递长列表和复杂数据结构。

当您使用引用（$rarch）时，对它的任何更改都会更改它作为引用的数据。这允许我们有效地更改呼叫者的数据。另一方面，当您在sub中取消引用它时，您将获得本地副本。这是更安全的，因为它的意外更改（错误）不会影响调用者。

请始终 use warnings;

当您调用af_exit并传递hashref

时，会重复相同的错误

af_exit($ARCH_CODES{$arch});

虽然它需要哈希

sub af_exit
{
     my %_error = @_;

以与上述相同的方式纠正它。

Answer 2

以下是使用传递引用的类似方法。希望你觉得它很有用。

有几点：

在你的foreach循环和子foo中，你传递的是标量，而不是散列引用。
您还可以使用shift在子例程中接收输入，然后取消引用该变量以检索该值。

在下面的示例代码中，在子例程foo中，我执行虚拟操作以将哈希映射传递给af_exit，仅当id为102或104时，仅作为示例。

这里我关闭了Data :: Dumper输出，我也没有打印子程序接收的引用类型的值。我们稍后会看到。

#!/usr/bin/perl

use strict ;
use warnings  ;
use Data::Dumper ;

my %ARCH_CODES = (
    armv7  => {id  => 102, desc => "aaaaaa"},
    i386   => {id  => 103, desc => "bbbbbb"},
    x86_64 => {id  => 104, desc => "cccccc"},
    arm64  => {id  => 105, desc => "dddddd"}
);

sub af_exit
{
        my $error = shift ;
        my $ref = ref $error ;
        #print "af_exit got variable which is of type $ref. Below is the Data Dumper output\n" ;
        #print Dumper $error ;
        print "${$error}{'id'}\n" ;
        #exit($$error{'id'});
        print "af_exit will perform exit on \[$$error{'id'}\]\n" ;
}

sub foo
{
        my $arch = shift ;
        my $ref = ref $arch ;
        #print "af_exit got variable which is of type $ref. Below is the Data Dumper output\n" ;
        #print Dumper $arch ;
        #my $res = runCommand("file zzz | grep \"$arch{id})\"");
        if ($$arch{id} == 102 || $$arch{id} == 104)
        {

                af_exit(\%$arch);
        }
}

for my $arch_ (keys %ARCH_CODES)
{
       foo(\%{$ARCH_CODES{$arch_}}) ;
}

结果：

%_04:04:54|root@[goat]:/home/ec2-user/cpp/study/temp> ./test
104
af_exit will perform exit on [104]
102
af_exit will perform exit on [102]
%_04:04:56|root@[goat]:/home/ec2-user/cpp/study/temp>

您始终可以使用Data :: Dumper并参考以准确显示传递的内容。再次使用Dumper和参考输出参见下面的结果。

%_04:09:19|root@[goat]:/home/ec2-user/cpp/study/temp> ./test
af_exit got variable which is of type HASH. Below is the Data Dumper output
$VAR1 = {
          'desc' => 'cccccc',
          'id' => 104
        };
af_exit got variable which is of type HASH. Below is the Data Dumper output
$VAR1 = {
          'desc' => 'cccccc',
          'id' => 104
        };
104
af_exit will perform exit on [104]
af_exit got variable which is of type HASH. Below is the Data Dumper output
$VAR1 = {
          'desc' => 'dddddd',
          'id' => 105
        };
af_exit got variable which is of type HASH. Below is the Data Dumper output
$VAR1 = {
          'desc' => 'aaaaaa',
          'id' => 102
        };
af_exit got variable which is of type HASH. Below is the Data Dumper output
$VAR1 = {
          'desc' => 'aaaaaa',
          'id' => 102
        };
102
af_exit will perform exit on [102]
af_exit got variable which is of type HASH. Below is the Data Dumper output
$VAR1 = {
          'desc' => 'bbbbbb',
          'id' => 103
        };
%_04:09:21|root@[goat]:/home/ec2-user/cpp/study/temp>

散列内部哈希，无法获取数据

2 个答案: