How to pass array and hash data types to subroutines arguments in perl? - perl

Question

I am facing compilation error while declaring array type argument in perl subroutine defination.
My complete code is below:
use Data::Dumper;
use Win32;
use Win32::Service;
use strict;
use warnings;
my #Services = qw(NNMAction RpcEptMapper smstsmgr SNMPTRAP);
my $server = 'nnmi.hclt.corp.hcl.in';
ServiceStatus($server , #Services);
sub ServiceStatus ($serverName,#serverServices)
{ my %statcodeHash = ( '1' => 'stopped',
'2' => 'start pending',
'3' => 'stop pending',
'4' => 'running',
'5' => 'continue pending',
'6' => 'pause pending',
'7' => 'paused' );
foreach my $serv (#serverServices)
{ my %status;
my $ret = Win32::Service::GetStatus($serverName , $serv , \%status);
if ($ret)
{ print "success \t$statcodeHash{$status{CurrentState}} \t$serv\n";
}
else
{ print Win32::FormatMessage(Win32::GetLastError()), "\n";
}
}
}
COMPILATION ERROR
>perl -w perl_RemoteServiceStatus.pl
Prototype after '#' for main::ServiceStatus : $serverName,#serverServices at per
l_RemoteServiceStatus.pl line 21.
Illegal character in prototype for main::ServiceStatus : $serverName,#serverServ
ices at perl_RemoteServiceStatus.pl line 21.
main::ServiceStatus() called too early to check prototype at perl_RemoteServiceS
tatus.pl line 16.
Global symbol "#serverServices" requires explicit package name at perl_RemoteSer
viceStatus.pl line 31.
Global symbol "$serverName" requires explicit package name at perl_RemoteService
Status.pl line 33.
Execution of perl_RemoteServiceStatus.pl aborted due to compilation errors.
Kindly help me debugging ths code. I am sure it would be a piece of cake for some.

Answer 1

It is really simple: Do not use prototypes if you do not know how they work. To get your code running, change the subroutine declaration from:
sub ServiceStatus ($serverName,#serverServices)
{ #...
to:
sub ServiceStatus {
my ($serverName, #serverServices) = #_;
edit: If you need to pass more than one array/hash to a subroutine, or an array/hash should be passed-in before some other value(s), you have to pass it by reference:
sub complex_params {
my ($array1, $scalar, $hash, $array2) = #_;
# dereference
my #a1 = #$array1;
my #a2 = #$array2;
my %h = %$hash;
#...
}
# reference
complex_params(\#some_array, $some_scalar, \%some_hash, \#other_array);

Answer 2

Perl prototypes are not for naming parameters, or even for giving types to them, they are for creating evaluation contexts. You need to modify the subroutines like this:
sub ServiceStatus ($#){
my ($serverName,#serverServices) = #_;
# ...
}
or totally get rid of the prototype:
sub ServiceStatus {
my ($serverName,#serverServices) = #_;
# ...
}

Answer 3

sub ServiceStatus
{
my ($serverName,#serverServices) = #_; # Declare variables and populate from #_, the parameter list.
...
}

Answer 4

what are you doing?
First! Don't try to use prototypes:
sub ServiceStatus($#){
}
Let's see, what you want:
Passing array or hash to function is a very old trick:
sub ServiceStatus{
my ($firstArgument, $refToSecondArgumentWhichIsArray) = #_;
#return undef unless defined($firstArgument&&$refToSecondArgumentWhichIsArray);
...
}
How to use this?
ServiceStatus($serverName, \#serverServices);
And what to do with refs?
$refToArray->[0]; <- first element of array you pass
#{$refToArray} <- array you pass to function