Perl Array References and avoiding "Type of arg 1 to keys must be hash" error
Replace
foreach my $s (keys $subscribers) {
with
foreach my $s (keys %$subscribers) { # $subscribers is hash ref
or
foreach my $s (0 .. $#$subscribers) { # $subscribers is array ref
From 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.
h q
Updated on July 17, 2022Comments
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h q almost 2 years
I have a scalar
$subscribers
that could be undef, reference to a HASH, or reference to an ARRAY. I have assigned the sample values$VAR1
,$VAR2
and$VAR3
for testing.I'm only interested in
$subscribers
when it is a reference to an ARRAY, where by it would contain multiple values. In other cases, I'm not interested in printing anything (e.g. when$subscribers=$VAR2;
The code seems to run fine under Perl v5.16.2; however, when I move it to the target machine running Perl v5.8.8, I get a compile error:
% ./test.pl Type of arg 1 to keys must be hash (not private variable) at ./test.pl line 23, near "$subscribers) " Execution of ./test.pl aborted due to compilation errors.
Code below:
#!/usr/bin/perl -w use strict; use warnings; use Data::Dumper; my $VAR1 = undef; my $VAR2 = {'msisdn' => '1234'}; my $VAR3 = [ {'msisdn' => '1111'}, {'msisdn' => '2222'}, {'msisdn' => '3333'}, {'msisdn' => '4444'}, {'msisdn' => '5555'} ]; my @childMsisdn = (); my $subscribers = $VAR3; if (ref $subscribers eq ref []) { # Exclude $VAR1 && $VAR2 scenarios foreach my $s (keys $subscribers) { my $msisdn = $subscribers->[$s]->{"msisdn"}; push (@childMsisdn, $msisdn); } } print "childMsisdn = ". join(",", @childMsisdn) ."\n";
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h q over 10 yearsThank you @mpapec. This works perfectly. I thought I tried this before, but clearly I didn't. Thanks for the prompt response. Cheers.