in reply to Undefined Subroutine & Global symbol requires explicit package name

Undefined subroutine &main::inet_aton called at dnscheck.pl line 15.
Hmmmm..... What exactly is unclear in this error message? It is pretty much plain English.

In case you wonder about the &main:: part: Subroutine names in Perl always belong to some package. If you don't write your own package definition, Perl assumes that you are in package main. Hence, Perl looks for the subroutine inet_aton in Package main.

-- 
Ronald Fischer <ynnor@mm.st>

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Re^2: Undefined Subroutine & Global symbol requires explicit package name
by jaldama (Acolyte) on Jan 24, 2012 at 16:27 UTC
    Yikes, yeah I didn't realize that "Global Symbol...." error was due a declaring issue, I've always declared them with 'my' but forgot and should have thought that through more, yaddayadda.. With the undefined subroutine problem, my issue was resolved by adding use Socket; duhhh! So from my understanding, that type of error will come up if you try to call some type of function incorrectly, say I write INET_ATON instead of inet_aton, because perl is case sensitive, right? Orrr, in this case, not 'using' the Socket or a module perhaps? Thanks as always
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      Perl is mostly case-sensitive. There is some ambiguity over case with regard to module names on case-insensitive file systems. For example, given the following module:

      # this code is in Foo/Bar.pm
package Foo::Bar;
use parent qw/Exporter/;
our @EXPORT = qw/baz/;
sub baz { "Hello world"; }
1;

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      On a Windows system (Windows a uses case-insensitive but case-preserving file system) you could do this:

      use 5.010;
use strict;
use foo::bar;
say Foo::Bar::baz(); # says "Hello world"

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      And you could do this:

      use 5.010;
use strict;
use Foo::Bar;
say baz(); # says "Hello world"

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      But you couldn't do this:

      use 5.010;
use strict;
use foo::bar;
say baz(); # dies - undefined subroutine main::baz

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      And you couldn't do this:

      use 5.010;
use strict;
use foo::bar;
say foo::bar::baz(); # dies - undefined subroutine again

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[select]
      You didn't really understand the first answer you got on the issue: "where did you find inet_aton documented?".

      When you call a subroutine, it must be defined somewhere, unless it is a builtin Perl function, like "each" and "print" in your example. In your code, you want to use functions from the module "Socket.pm" - so you have to "use Socket" to make these functions available.

      You can tell that inet_aton is not a Perl function simply by checking with man perlfunc or by trying 

      perldoc -f inet_aton

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      Of course, if you misspell a function you'll get the same error, but this is not the issue here.

      further documentation

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In Section Seekers of Perl Wisdom