Re^2: Print hash keys and lookup the keys for values in another filr

I didn't comment on this section before since the program seems to have had very little effort put into it. The last if !line; part will never do anything even if corrected since $line is only declared and assigned a value if the regex matches.

  my $line = $_ if /\bWood\b/;
    chomp ($line);
    last if !line;
[download]

Perhaps something like last if /^\s*$/ placed ahead of the my $line = $_ ... would work.

Comment on Re^2: Print hash keys and lookup the keys for values in another filr Select or Download Code

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Re^3: Print hash keys and lookup ... by haukex (Archbishop) on Feb 02, 2017 at 12:43 UTC
Hi Lotus1, The `last if !line;` part will never do anything even if corrected Turns out I missed it yesterday - the line does do something: `$ perl -wMstrict -n my $line = $_ if /\bWood\b/; chomp ($line); print "BANG!\n" if !$line; __END__ Hello, Wood World Foobar` [download] Outputs: `Use of uninitialized value $line in scalar chomp at - line 2, <> line +2. BANG!` [download] The `... if !$line` gets triggerd when `$line` is false, which is a case that can happen. There's another thing I missed yesterday: `my $line = $_ if /\bWood\b/;`, to which perlsyn has to say this: NOTE: The behaviour of a `my`, `state`, or `our` modified with a statement modifier conditional or loop construct (for example, `my $x if ...`) is undefined. The value of the `my` variable may be `undef`, any previously assigned value, or possibly anything else. Don't rely on it. Future versions of perl might do something different from the version of perl you try it out on. Here be dragons. So really, that entire loop body needs a rewrite, maybe: `while (<$fh>) { chomp; next unless /\bWood\b/; ... }` [download] Regards, -- Hauke D	[reply] [d/l] [select]
Re^4: Print hash keys and lookup ... by Lotus1 (Vicar) on Feb 02, 2017 at 14:42 UTC
Good points. Using `my` in a conditional statement is something I got burned by a while back and quit doing and forgot why.	[reply] [d/l]
Re^3: Print hash keys and lookup ... (updated) by haukex (Archbishop) on Feb 01, 2017 at 17:00 UTC
Hi Lotus1, The `last if !line;` part will never do anything even if corrected You're right of course, I was at that moment more focused on getting the code compiling, and there was lots more to explain, so I skipped the line ~~that doesn't do anything~~ :-) Update: Oops, the line does do something, see my other reply. Thanks, -- Hauke D	[reply] [d/l]