ranged conditional with variable

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

I'm attempting to do the following, be receive the following error: "Use of uninitialized value in pattern match (m//)"

foreach my $line (<FILE>) {
    if ($line =~ /PatternBegin/ .. /PatternEnd/) {
        $str .= $line;
    }
}
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If i remove the variable declaration and work from $_ with the following code everything works fine.

foreach (<FILE>) {
    if (/PatternBegin/ .. /PatternEnd/) {
        $str .= $_;
    }
}
[download]

How do I make it work with the first example of code?

Comment on ranged conditional with variable Select or Download Code

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Re: ranged conditional with variable by diotalevi (Canon) on Aug 22, 2006 at 00:04 UTC
You thought the second match would use $line because the first did. It didn't. You didn't provide a target for `/PatternEnd/` so it bound to $_. Write it using the second example I've quoted. `# You wrote if ( $line =~ /PatternBegin/ .. $_ =~ /PatternEnd/ ) { # You wanted. if ( $line =~ /PatternBegin/ .. $line =~ /PatternEnd/ ) {` [download] ⠤⠤ ⠙⠊⠕⠞⠁⠇⠑⠧⠊	[reply] [d/l] [select]
Re: ranged conditional with variable by ikegami (Patriarch) on Aug 22, 2006 at 05:57 UTC
Furthermore, `foreach (<FILE>) {` reads the whole file into memory, even though you only work on one line at a time. Use `while (<FILE>)` or (`while (defined(my $line = <FILE>))`) instead.	[reply] [d/l] [select]
Re: ranged conditional with variable by izut (Chaplain) on Aug 22, 2006 at 11:41 UTC
I'm curious. What are you trying to do with that pattern matching? I've seen `..` usage just in arrays, or iteration. Could you enlight me? Igor 'izut' Sutton your code, your rules.	[reply] [d/l]
Re^2: ranged conditional with variable by Hofmator (Curate) on Aug 22, 2006 at 12:11 UTC
What you know is probably `..` in list context. The OP is using `..` in scalar context (the so called flip-flop operator), see `perldoc perlop -> Range Operators` -- Hofmator	[reply] [d/l] [select]
Re^3: ranged conditional with variable by izut (Chaplain) on Aug 22, 2006 at 12:29 UTC
Thanks for your reply! We are always learning Perl magics :-) Igor 'izut' Sutton your code, your rules.	[reply]