Hash value being called as a Scalar?

c has asked for the wisdom of the Perl Monks concerning the following question:

I am absolutely positive that I have seen this in books as a typical user syntax issue, but I just sold my Cozens book so, I have to turn to the monastery.

My code, is pretty basic

#!/usr/bin/perl -w

## module calls
use strict;
use Net::SNMP;
  ## start snmp session
  my $s = Net::SNMP->session( -hostname  => "10.6.21.10",
                                -community => "private" );
  
  ## run the get
  my $ios_version = $s->get_request(".1.3.6.1.2.1.1.1.0");

  my $error = $s->error;

  ## close the snmp session
  $s->close;

  ## print results
  print "$error\n$ios_version\n\n";
[download]

however the output of $ios_version ends up being

HASH(0x811fb50)

i am sure that i have seen this error before, and i had thought it had something to do with trying to represent a hash value as a scalar or vice versa. however, making $ios_version into @ios_version still provides the same output. can someone beat this into my head one more time so it stays?

humbly -c

Comment on Hash value being called as a Scalar? Download Code

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Re: Hash value being called as a Scalar? by stefp (Vicar) on Oct 08, 2001 at 21:07 UTC
`print "$error\n$ios_version\n\n";` however the output of $ios_version ends up being HASH(0x811fb50) The output shows that $ios_version is a reference to hash. Using double quotes is not the proper way to (s)print a composite data structure. One generic way is provided by Data::Dumper. `use Data::dumper; ... print Dumper $ios_version;` [download] -- stefp	[reply] [d/l] [select]
Re: Hash value being called as a Scalar? by tune (Curate) on Oct 08, 2001 at 20:59 UTC
Then $s must be a hash reference. Read more at perlref docs. UPDATE: i meant $ios_version :) -- tune	[reply]
Re: Hash value being called as a Scalar? by mr_dont (Beadle) on Oct 08, 2001 at 21:04 UTC
It looks like you are printing a reference, rather than the item being "referenced". Try to access the ios_version by de-referencing the variable using: `## print results ## notice the extra "$" in front of the variable print "$error\n$$ios_version\n\n";` [download] The "$$" provides access to the actual data, rather than the reference, which simply "points" to the location of data	[reply] [d/l]
Re: Hash value being called as a Scalar? by Rex(Wrecks) (Curate) on Oct 08, 2001 at 23:55 UTC
Now I don't know Net::SNMP and I'm to lazy to look it up :) However it looks to me like the key to this problem is finding out what the `->get_request` method is expected to return! If you are expecting a scalar then you are having problems, if the method actually returns a hashref then your problem is fairly clear, you need to access the data in a different manner than using it as a simple scalar. Use the debugger and set a bp after the `->get_request`, then try printing and dumping your var in several different ways until you get what you want, alternatively step through the `->get_request` code in the debugger and find out what it is doing. "Nothing is sure but death and taxes" I say combine the two and its death to all taxes!	[reply] [d/l] [select]
Re: Hash value being called as a Scalar? by converter (Priest) on Oct 09, 2001 at 06:18 UTC
Read The Fine Manual The Net::SNMP manpage clearly states what is returned by the `get_request` method when called in blocking mode (which is the way you're calling it in your example), and includes helpful examples that illustrate how to use the return value. conv	[reply] [d/l]