Re^2: Data::Dumper / write output into Mysql

Hi hippo, The code you've helped me with works pretty well but if I understand the error correctly it seems like when the device isn't answering in time passing a value back to the script I'm getting the following error. Can't use an undefined value as a HASH reference at ./smwalker.pl line 152. ### This is basically Line 152

for my $mac (values %{(values %$result)[0]}) {
    print "Mac addr: $mac\n";
}
[download]

How do I deal with this ? Thanks in advance,

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Re^3: Data::Dumper / write output into Mysql by hippo (Archbishop) on Nov 05, 2015 at 13:30 UTC
On a modern enough perl you can use the defined-or operator `//` to use an empty hashref instead. eg: `use strict; use warnings; my $result = { '10.4.20.21' => undef }; for my $mac (values %{(values %$result)[0] // {}}) { print "Mac addr: $mac\n"; }` [download] Of course, if your entire `$result` is undef then you could easily check for this separately before even hitting the for loop.	[reply] [d/l] [select]
Re^4: Data::Dumper / write output into Mysql by steph007 (Initiate) on Nov 05, 2015 at 13:41 UTC
I'm guessing I'll be doing something like this to check whether the entire $result is undef ? `unless (defined($result)) { ....blah }` [download]	[reply] [d/l]