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

In the following chunk, how can I have the print "\n == hash key == $oid{$value} ==\n"; line print the hash key as well as the value?
    thanks in advance,
    Don
    striving toward Perl Adept
    (it's pronounced "why-bick") 
#! /usr/bin/perl

require 5.6.1;                                      # for Net::SNMP v4
use strict;                                         # avoid D'oh! prob
+lems
use warnings;                                       # avoid D'oh! prob
+lems
use Net::SNMP 4 qw(snmp_dispatcher oid_lex_sort);   # must be >= versi
+on 4
use Tie::IxHash;                                    # insertion-order 
+retrieval

my ($session, $error) = Net::SNMP->session(
  -hostname  => 'catalyst',
  -community => 'public',
);
unless (defined($session)) {
  print "Error: $error";
  exit;
}

tie my %oid, "Tie::IxHash";
%oid = (
  TpFdbAddress  => '.1.3.6.1.2.1.17.4.3.1.1',
  TpFdbPort     => '.1.3.6.1.2.1.17.4.3.1.2',
  bridgePortNum => '.1.3.6.1.2.1.17.1.4.1.1',
  switchPortNum => '.1.3.6.1.2.1.17.1.4.1.2',
  ifDescr       => '.1.3.6.1.2.1.2.2.1.1',
  ifName        => '.1.3.6.1.2.1.31.1.1.1.1',
);

for my $value (keys %oid) {
  if (defined(my $response = $session -> get_table(-baseoid => $oid{$v
+alue}))) {
    print "\n == hash key == $oid{$value} ==\n";
    for my $r(oid_lex_sort(keys(%{$response}))) {
      print($response -> {$r}, ",\n");
    }
  }
  else { print "Error: ",($session -> error(), ",\n"); }
}

$session->close;
exit;

[download]

Replies are listed 'Best First'.
Re: Print hash value and key in for keys loop
by danboo (Beadle) on Dec 14, 2001 at 02:25 UTC
    I think you may be confused about which is the the key and which is the value. For instance; you say "for my $value (keys %oid) {" as though you expect to get a list of values when your actually getting keys. And in your print statement you have "hash key == $oid{$value}" which is printing the value and not the key.

    A hash is key/value pairs. You use the keys to lookup the corresponding values. Perhaps what you want is: 

    for my $key (keys %oid) {
  if (defined(my $response = $session -> get_table(-baseoid => $oid{$k
+ey}))) {
    print "\n == hash key == $key == hash value == $oid{$key} ==\n";
    for my $r(oid_lex_sort(keys(%{$response}))) {
      print($response -> {$r}, ",\n");
    }
  }
  else { print "Error: ",($session -> error(), ",\n"); }
}

    [download]
    - danboo
[reply]
[d/l]
      Thanks for the quick answer, brother danboo - that does the trick.   8^)

      Actually, I do understand which is key and which is value (at least in the declaration chunk).   What's cornfusing here is that $oid{key} refers to the key, while $key refers to the value.   So to avoid that puzzlement, here's what I'm doing for now: 

      for (keys %oid) {
  if (defined(my $response = $session -> get_table(-baseoid => $oid{$_
+}))) {
    print "\n == $_ == $oid{$_} ==\n";
    for my $r(oid_lex_sort(keys(%{$response}))) {
      print($response -> {$r}, ",\n");
    }
  }
  else { print "Error: ",($session -> error(), ",\n"); }
}

      [download]

          cheers,
          Don
          striving toward Perl Adept
          (it's pronounced "why-bick")

      Update:
      Hrm... as good monk danboo points out below, I mispoke.   What I meant to say is "What's cornfusing here is that $oid{key} refers to the value, while $key refers to the key."   I really do understand key and value...   really...   honest   {grin}

[reply]
[d/l]
        My pleasure to assist, though I think we're still not in agreement on our terms. $oid{$key} is not the key; $key is. $oid{$key} is the value. By using the key in the hash %oid we get back the value in return.

        Hopefully I'm not confusing the situation.

        - danboo

[reply]
[d/l]
[select]
Re: Print hash value and key in for keys loop
by Zaxo (Archbishop) on Dec 14, 2001 at 02:42 UTC
    print "\n == $value == $oid{$value} ==\n";

    After Compline,
    Zaxo

[reply]
[d/l]

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