Perl array has values but unable to access them

Question

I have tried, I have searched in the internet and I am out of ideas at this moment. I have an array which has elements. I use to Dumper function to ensure that the elements are present however, when I try to access individual items, I don't get the expected output.

And someone please help.

This is the code

print "<pre>Array: ".Dumper(@configFiles)."\n";
print "First: ".$configFiles[0]."\n";
print "Second: ".$configFiles[1]."</pre>";

Below is the output

Array: $VAR1 = [
      'searchTables.json',
      'NAM_database.json'
    ];

First: ARRAY(0x9a8f60)
Second:

In case you are wondering how were the array elements assigned, I read a json file then converted it with the function below.

sub parseJson{
    my ($jfilename) = @_;
    if(-e "$jsoncPath/$jfilename"){
        return decode_json($json_data);
    }else{

    }
}

See the json below

[
   "searchTables.json",
   "NAM_database.json"
]

I also tried de-referencing as seen below with no success

print "<pre>First: ".@{$configFiles[0]}."</pre>";

give me what is sceen below.

First: 2

Tip: If you want to dump an array or hash, best to pass a reference. Dumper(\@configFiles). — ikegami
– ikegami, Commented Aug 28, 2014 at 14:52
Thanks for that note, this provide a better picture of what is within the array. — Andre Dixon
– Andre Dixon, Commented Aug 28, 2014 at 15:21

Miller · Accepted Answer · 2014-08-28 19:22:48Z

3

decode_json returns a reference to an array not the actual array. Should be:

my $configFiles = parseJson($jfilename);
print "<pre>Array: " . Dumper($configFiles) . "\n";
print "First: " . $configFiles->[0] . "\n";
print "Second: " . $configFiles->[1] . "</pre>";

or

print "<pre>Array: " . Dumper(@configFiles) . "\n";
print "First: " . $configFiles[0][0] . "\n";
print "Second: " . $configFiles[0][1] . "</pre>";

edited Aug 28, 2014 at 19:22

Miller

35.3k4 gold badges42 silver badges61 bronze badges

answered Aug 28, 2014 at 13:48

Andrey

1,8281 gold badge17 silver badges28 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Andre Dixon Over a year ago

This worked $configFiles[0]->[0] and also the following @{$configFiles[0]}[0]

ikegami Over a year ago

$configFiles[0]->[0] can be shortened to $configFiles[0][0]

TLP · Accepted Answer · 2014-08-28 14:06:33Z

2

The @configFiles is not the array you think/expect. The first element is an array reference, you need to dereference it to access the array:

print "ARRAY: @{$configFiles[0]}\n";

edited Aug 28, 2014 at 14:06

TLP

68.2k10 gold badges97 silver badges156 bronze badges

answered Aug 28, 2014 at 13:50

glezmen

5542 silver badges5 bronze badges

3 Comments

Andre Dixon Over a year ago

I tried this with no success print "<pre>First: ".@{$configFiles[0]}."</pre>"; give me what is sceen below. First: 2

TLP Over a year ago

@AndreDixon In scalar context, an array returns its size, not its elements. Using the concatenation operator . puts an array in scalar context. If you just use interpolation you'd be fine: print "<pre>First: @{$configFiles[0]}</pre>"

Dave Cross Over a year ago

Or just change your concatenation dot into a comma - print "<pre>First: ", @{$configFiles[0]}."</pre>";

Collectives™ on Stack Overflow

Perl array has values but unable to access them

2 Answers 2

2 Comments

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related