Name "main::NETOBJ" used only once: possible typo at t.pl line 6.
Use of uninitialized value in scalar dereference at t.pl line 6.
Use of uninitialized value in concatenation (.) at t.pl line 6.
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• Because "$$NETOBJ.parameter" is in double quotes, Perl is interpreting $NETOBJ as a variable, and trying to interpolate its value. Because it doesn't have a value, you get an undef value.
• Now, the first "$" in "$$NETOBJ" is also interpolated by perl, trying to interpret it as a dereference to $NETOBJ (this is, if $NETOBJ contained a reference to a scalar value, $$NETOBJ would dereference it and give you the value). Because $NETOBJ is undef, the dereferencing fails too, This produces the "Use of uninitialized value in scalar dereference" error.
• At this point $a contains already ".parameter".
• The substitution is escaped correctly, therefore it looks for the string '$$NETOBJ'. But that string is not there, therefore the substitution doesn't happen, and you get ".parameter" as your final result

$a='$$NETOBJ.parameter';
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--ZZamboni

Thanks to everyone for their helpful responses.
Actually, I was trying to keep my post brief, but I ended up leaving out too much information and still getting helpful information, but not the exact information I was seeking.

Ok, here's the story:
I'm parsing a config file and I'm running into a parameter that has a value like $$NETOBJ.parameter. I want to remove the $$NETOBJ. part and be left with parameter. The code I submitted earlier was a little test that I had put together, but I mistyped it. Here is my test program as I was using it:

#!/usr/local/bin/perl

$a = "$$NETOBJ.parameter";

$a =~ s/\$\$NETOBJ\.//;

print $a;
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Earlier, I typed use strict; out of habit. I usually use it, but left it out for this small example.
What the code above gives me is .parameter. My question is: Why doesn't my regexp remove the dot? I don't need to know how to create the value because I'm already reading it from the config file. I need to know how to remove the dot.

Sorry again for not being more specific. Thank you all for your feedback.

Tii

The regex doesn't remove the dot because the regex doesn't match. Let's make two small changes:

#!/usr/local/bin/perl -w

$a = "$$NETOBJ.parameter";
print ">>$a<<\n";
$a =~ s/\$\$NETOBJ\.//;

print $a;
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You might also write it this way:

$a = "$$NETOBJ.parameter";

if ($a =~ s/\$\$NETOBJ\.//) {
    print $a;
} else {
    print "Substitution failed.\n";
}
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One other approach that may work for you is split:

$a = '$$NETOBJ.parameter';
(undef, $a) = split(/\./, $a, 2);
print $a;
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Of course, notice the single quotes in the declaration that time. That'll help even if you do use the regexp.

Global symbol "$NETOBJ" requires explicit package name at F:\reg.pl li
+ne 7.
Execution of F:\reg.pl aborted due to compilation errors.
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parameter
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$a = '$$NETOBJ.parameter';
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  use strict;

  my $a;

  $a = "\$\$NETOBJ.parameter";

  $a =~ s/\$\$NETOBJ\.//;

  print $a;
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-- Abigail

$a =~ s/\Q$$NETOBJ.// or die "$a is not right";
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$a =~ s/\$\$NETOBJ\.// or die "$a is not right";
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Actually, that would not have helped at all. The \Q will turn off interpretation of regular expression meta characters, but it will not prevent interpolation to happen. Hence, with use strict; in effect, the thing would still not compile, and without strict $$NETOBJ would be the empty string (warnings were disabled - so you don't get that error message), and the substitution would successfully remove the dot. Hence, the die would not happen.

-- Abigail

I believe that "$!" would make the "or die" even better, by providing information on why the regex didn't check.

If so, that gives you:

$a =~ s/\$\$NETOBJ\.// or die "$a is not right: $!";
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I mentioned in my reply to ZZamboni that I was testing a program in which I was reading data from a config file. I created the string with text to simulate what I was reading from the file.

I decided a different approach:
I created a text file with the line $$NETOBJ.parameter in it. Then I changed my code to the following:

#!/usr/local/bin/perl

open (F, "textfile") or die "Could not open file: $!";

$a = <F>;

$a =~ s/\$\$NETOBJ\.//;

print $a;
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This code outputs parameter. It turns out that the way I was simulating reading text from a file was part of my problem.
Thanks to everyone for the help.

Humbly,
Tii