in reply to Simple hash assignment...or is it?

You can use the Data::Dumper module to investigate your hash and array structures.
use Data::Dumper;

...

# insert after the first foreach loop.
print Dumper(\@tcp_utilization_metrics);

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Re: Re: Simple hash assignment...or is it?
by arootbeer (Novice) on Nov 22, 2003 at 01:05 UTC
    The Dumper output shows me the same thing as my own print statements: that there's some difference between the interface names I'm passing into the foreach block, and what's getting set as hash keys. It's a very confusing problem: 
    $VAR1 = (                 
          'en0',          
          'en1'           
        );                
en0: ent0                 
ent0                      
en1: ent1                 
ent1                      
$VAR1 = {                 
          'en0' => 'ent0',
          'en1' => 'ent1' 
        };                
(empty line)
(empty line)

    because, as you can see, the hash keys are the same string as the members of the array.

[reply]
      I have rewritten your code to make it a bit Perl like. The following code is equivalent to your code -
      use strict;
use Data::Dumper;

my $network_ifs = `netstat -i | grep -Ev "lo|sit|link|Name" | cut -f1 
+-d" " | uniq | sort -n`;

my @tcp_utilization_metrics = split '\n', $network_ifs;

my %tcp_utilization_adapter_names;

foreach my $network_if (@tcp_utilization_metrics) {
    next if ! $network_if; # ignore empty lines if any
    my $if_name = $network_if;

    if ($network_if =~ /en/) {
        substr($network_if, 2, 0) = "t";   # insert 't'
    } elsif ($network_if =~ /tr/) {
        substr($network_if, 1, 2) = "ok";  # replace 'ok'
    } elsif ($network_if =~ /at/) {
        substr($network_if, 2, 0) = "m";   # insert 'm'
    }
    # insert hash entries
    $tcp_utilization_adapter_names{$if_name} = $network_if;
}

# investigate the hash
foreach (keys %tcp_utilization_adapter_names) {
    print "$tcp_utilization_adapter_names{$_}\n";
}

      [download]
      Perhaps you could tell us what is your expected hash output. I highly suspect that you want the following instead in your code (swap the key-value in the hash) -
      # insert hash entries
$tcp_utilization_adapter_names{$network_if} = $if_name;

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[reply]
[d/l]
[select]

        Thanks...I'm sure you can tell I come from a C++/Java upbringing. The hash that Dumper displays is exactly what I want the hash to look like. The problem is that the keys (in @tcp_utilization_metrics) which are used to create the hash, don't seem to work to retrieve values from the hash. That's what has me so confused: both the hash and the array LOOK right, but something I don't know about ISN'T right.

[reply]
[d/l]
        mpeppler figured it out for me...see below. Thanks for your help!
[reply]

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