Re: Need help with s///

The substitution is never happening, that's why. And there must be something else you omitted, because as shown, your code does not run because the $NETOBJ variable is not declared anywhere. Removing the "use strict" makes it run, and running it with the -w flag (always use -w and strict!) shows you the problem:

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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Ok, here's what is happening:

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

The solution if you want the literal string '$$NETOBJ' in $a is to use single quotes instead of double quotes. The single quotes prevent interpolation. Like this:

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

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RE: Re: Need help with s/// by Tii (Monk) on Jul 15, 2000 at 07:01 UTC
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 = "$$NETOBJ.parameter"; $a =~ s/\$\$NETOBJ\.//; print $a;` [download] Earlier, I typed use strict; out of habit. I usually use it, but left it out for this small example. What the code above gives me is .parameter. My question is: Why doesn't my regexp remove the dot? I don't need to know how to create the value because I'm already reading it from the config file. I need to know how to remove the dot. Sorry again for not being more specific. Thank you all for your feedback. Tii	[reply] [d/l]
(chromatic) RE: RE: Re: Need help with s/// by chromatic (Archbishop) on Jul 15, 2000 at 07:09 UTC
The regex doesn't remove the dot because the regex doesn't match. Let's make two small changes: `#!/usr/local/bin/perl -w $a = "$$NETOBJ.parameter"; print ">>$a<<\n"; $a =~ s/\$\$NETOBJ\.//; print $a;` [download] You might also write it this way: `$a = "$$NETOBJ.parameter"; if ($a =~ s/\$\$NETOBJ\.//) { print $a; } else { print "Substitution failed.\n"; }` [download] One other approach that may work for you is split: `$a = '$$NETOBJ.parameter'; (undef, $a) = split(/\./, $a, 2); print $a;` [download] Of course, notice the single quotes in the declaration that time. That'll help even if you do use the regexp.	[reply] [d/l] [select]