数组 – Perl数组引用并避免“arg 1到键的类型必须是哈希”错误

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我有一个标量$订阅者可能是undef,引用HASH或引用ARRAY.我已经为测试分配了样本值$VAR1,$VAR2和$VAR3.

当它是对ARRAY的引用时,我只对$subscriber感兴趣,其中它包含多个值.在其他情况下,我对打印任何东西都不感兴趣(例如,当$subscriber = $VAR2;

在Perl v5.16.2下,代码似乎运行正常;但是,当我将它移动到运行Perl v5.8.8的目标机器时,我收到编译错误

  1. % ./test.pl
  2. Type of arg 1 to keys must be hash (not private variable) at ./test.pl line 23,near "$subscribers) "
  3. Execution of ./test.pl aborted due to compilation errors.

代码如下:

  1. #!/usr/bin/perl -w
  2.  
  3. use strict;
  4. use warnings;
  5. use Data::Dumper;
  6.  
  7. my $VAR1 = undef;
  8.  
  9. my $VAR2 = {'msisdn' => '1234'};
  10.  
  11. my $VAR3 = [
  12. {'msisdn' => '1111'},{'msisdn' => '2222'},{'msisdn' => '3333'},{'msisdn' => '4444'},{'msisdn' => '5555'}
  13. ];
  14.  
  15. my @childMsisdn = ();
  16. my $subscribers = $VAR3;
  17.  
  18. if (ref $subscribers eq ref []) { # Exclude $VAR1 && $VAR2 scenarios
  19. foreach my $s (keys $subscribers) {
  20. my $msisdn = $subscribers->[$s]->{"msisdn"};
  21. push (@childMsisdn,$msisdn);
  22. }
  23. }
  24. print "childMsisdn = ". join(",",@childMsisdn) ."\n";

解决方法

更换
  1. foreach my $s (keys $subscribers) {

  1. foreach my $s (keys %$subscribers) { # $subscribers is hash ref

要么

  1. foreach my $s (0 .. $#$subscribers) { # $subscribers is array ref

perldoc

Starting with Perl 5.14,keys can take a scalar EXPR,which must contain a reference to an unblessed hash or array. The argument will be dereferenced automatically. This aspect of keys is considered highly experimental. The exact behavIoUr may change in a future version of Perl.

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