Printing content of ARRAY inside hash - perl

Question

how do I print a content of an array inside the hash? I am using Dumper so you can see the data that I am parsing.
print Dumper \%loginusers;
for my $key ( keys %loginusers ) {
my $value = $loginusers{$key};
print "$key => $value\n";
}
printf "%s %-32s %-18s\n","User","Hostname","Since";
The output is
$VAR1 = {
'server1.localdomain.com:8080' => [
', 'user=user1
' 'since=2017-03-10 13:53:27
]
};
server1.localdomain.com:8080 => ARRAY(0x1584748)
User Hostname Since
As you can see there is an ARRAY(0x1584748) and I don't know how to get that value inside from the hash.
What I would like to see is something like:
User Hostname Since
user1 server1.localdomain.com:8080 2017-03-10 13:53:27
Thank you very much for someone that can help.
Update:
So after trying this to see the data how it looks:
foreach my $key (keys %loginusers)
{
print "For $key:\n";
print "\t|$_|\n" for #{$loginusers{$key}};
}
The output looks like this:
For server1.localdomain.com:8080:
| |user=user1
| |since=2017-03-10 13:53:27
Update:
tried the add these on the code:
foreach my $key (keys %loginusers)
{
my #fields =
map { s/^\s*//; s/\s*\Z//; s/\s*\n\s*/ /g; $_ }
grep { /\S/ }
#{$loginusers{$key}};
print "For $key:\n";
print "$_\n" for #fields;
}
And using the both sample code:
printf "%-8s %-32s %s\n", qw(User Hostname Since);
foreach my $key (keys %loginusers)
{
my %field = map { /\s*(.*?)=\s*(.*)/ } #{$loginusers{$key}};
my ($host, $rgsender, $port) = split /:/, $key;
printf "%-8s %-32s %s\n", $field{user}, $host, $field{since};
}
my $newusers;
for my $host ( keys %loginusers ) {
local $/ = "\r\n"; #localised "input record separator" for the "chomp"
%{$newusers->{$host}} = map { chomp; split /=/,$_,2 } #{$loginusers{$host}};
}
undef %loginusers; #not needed anymore
#print "NEW STRUCTURE: ", Dumper $newusers;
printline( qw(User Hostname Since) );
printline($newusers->{$_}{user}, $_, $newusers->{$_}{since}) for (keys %$newusers);
sub printline { printf "%-8s %-32s %-18s\n", #_; }
and here is the results:
User Hostname Since
user1 server1.localdomain.com:8080 2017-03-10 13:53:27
User Hostname Since
user1 server1.localdomain.com:8080 2017-03-10 13:53:27

Answer 1

A hash value is a scalar, and it can take a reference. This is how we build complex data structures. Yours apparently have arrayrefs, so you need to dereference them. Something like
foreach my $key (keys %hash) {
say "$key => #{$hash{key}}";
}
See the tutorial perlretut and the cookbook on data structures perldsc.
The strange output from Dumper indicates that there may be leading/trailing spaces around values (or worse), which need be cleaned out. Until this is clarified I'll assume data like
'server1.localdomain.com:8080' => ['user=user1', 'since=2017-03-10 13:53:27']
In order to get the desired output you need to split each element
printf "%-8s %-32s %s\n", qw(User Hostname Since);
foreach my $key (keys %hash)
{
my ($user, $since) = map { /=\s*(.*)/ } #{$hash{$key}};
printf "%-8s %-32s %s\n", $user, $key, $since;
}
For each value, we dereference it and pass that through map. The code in maps block, that is applied to each element, pulls what is after =. Given the data, the first one is the user and the second one is timestamp. Since this is an array (and not a hash) I assume that the order is fixed. If not, get strings from both sides of = and analyze them to see which one goes where. Or better use a hash
my %field = map { /\s*(.*?)=\s*(.*)/ } #{$hash{$key}};
where .*? is the non-greedy version of .*, capturing until the first =. Then print as
printf "%-8s %-32s %s\n", $field{user}, $key, $field{since};
and you don't rely on the order in the arrayref. See the answer by jm666 for a nice and consistent approach building this from the beginning.
With the hash shown above this prints
User Hostname Since
user1 server1.localdomain.com:8080 2017-03-10 13:53:27
I've used 8 and 32 widths based on shown data. For more precision, there are modules for tabular output. If you do it by hand you need to pre-process and find the longest word for each column among keys and/or values, and then use those lengths in the second pass with printf.
It appears that Dumper is getting confused by strange data. To see what we have do
foreach my $key (keys %loginusers)
{
print "For $key:\n";
print "\t|$_|\n" for #{$loginusers{$key}};
}
To clean up the data you can try
foreach my $key (keys %loginusers)
{
my #fields =
map { s/^\s*//; s/\s*$//; s/\s*\R\s*/ /g; $_ }
grep { /\S/ }
#{$loginusers{$key}};
print "For $key:\n";
print "$_\n" for #fields;
}
The grep takes an input list and filters out those elements for which the code inside its block evaluates false. Here we require at least one non-space character. Then its output goes into map, which removes all leading and trailing whitespace, and replaces all newlines with spaces.

Answer 2

The your data-structure isn't very nice. I would convert it to some better, using:
#convert to better structure
my $newusers;
for my $host ( keys %loginusers ) {
%{$newusers->{$host}} = map { chomp; split /=/,$_,2 } #{$loginusers{$host}};
}
undef %loginusers; #the old not needed anymore
print "NEW STRUCTURE: ", Dumper $newusers;
The dump now looks like:
NEW STRUCTURE: $VAR1 = {
'server1.localdomain.com:8080' => {
'user' => 'user1',
'since' => '2017-03-10 13:53:27'
}
};
after the above the printing is simple:
printline( qw(User Hostname Since) );
printline($newusers->{$_}{user}, $_, $newusers->{$_}{since}) for (keys %$newusers);
sub printline { printf "%-8s %-32s %-18s\n", #_; }
For the explanation read #zdim's excellent answer (and accept his answer :))
full code
use 5.014;
use warnings;
use Data::Dumper;
my %loginusers = (
'server1.localdomain.com:8080' => [
"user=user1\r\n", # you probably have the \r too
"since=2017-03-10 13:53:27\r\n",
]
);
say "OLD STRUCTURE: ", Dumper \%loginusers;
#convert to better structure
my $newusers;
for my $host ( keys %loginusers ) {
%{$newusers->{$host}} = map { s/[\r\n]//g; split /=/, $_, 2 } #{$loginusers{$host}}; #removes all \r and \n
}
undef %loginusers; #not needed anymore
say "NEW STRUCTURE: ", Dumper $newusers;
printline( qw(User Hostname Since) );
printline($newusers->{$_}{user}, $_, $newusers->{$_}{since}) for (keys %$newusers);
sub printline { printf "%-8s %-32s %-18s\n", #_; }
result:
OLD STRUCTURE: $VAR1 = {
'server1.localdomain.com:8080' => [
'user=user1
',
'since=2017-03-10 13:53:27
'
]
};
NEW STRUCTURE: $VAR1 = {
'server1.localdomain.com:8080' => {
'user' => 'user1',
'since' => '2017-03-10 13:53:27'
}
};
User Hostname Since
user1 server1.localdomain.com:8080 2017-03-10 13:53:27
EDIT
You probably have the \r in your data too. See the updated code.