Re^2: Extract Multiple Lines from the End of a multi-line string

It works great but I'm not sure I understand completely.

'^' . ( '.*\\n' x ($N-1) ) .
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This matches the penultimate lines.

'(?:.+|.*\\n)'
[download]

I'm a little fuzzier on this bit. ?: is for a non-captured group I think, the .*\\n must be the last line especially when used with the \z but what is the +| for? and also the [0] on the end of the return?

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Re^3: Extract Multiple Lines from the End of a multi-line string by ikegami (Patriarch) on Oct 17, 2008 at 00:08 UTC
I defined a line as either "zero or more non-newline characters followed by a newline (`/.\n/`)" or "one or more non-newline characters (`/.+/`)". That way, `"foo\nbar\n"` is considered to have two lines (`"foo\n"` and `"bar\n"`) `"foo\nbar"` is considered to have two lines (`"foo\n"` and `"bar"`) That's the same behaviour as `<FH>`. If I had used `/.\n?/` instead of `/.*\n\|.+/`, `"foo\nbar\n"` would have been considered to have three lines (`"foo\n"`, `"bar\n"` and `""`). Always be wary of patterns that can match zero characters.	[reply] [d/l] [select]
Re^3: Extract Multiple Lines from the End of a multi-line string by ikegami (Patriarch) on Oct 17, 2008 at 00:11 UTC
Oops, missed the second question. and also the `[0]` on the end of the return? In list context, the match operator returns what it captured. I used a list slice to force list context. `$x = 'abc' =~ /a(.)c/; # 1 (or false on fail) @x = 'abc' =~ /a(.)c/; # b (or () on fail) $x = ( 'abc' =~ /a(.)c/ )[0]; # b (or undef on fail)` [download] I could also have used `$x = 'abc' =~ /a(.)c/ && $1; # b (or false on fail)` [download]	[reply] [d/l] [select]
Re^4: Extract Multiple Lines from the End of a multi-line string by NateTut (Deacon) on Oct 17, 2008 at 16:15 UTC
Thanks for the explanation. I was trying to do something like (.*\n){5} and was getting nowhere.	[reply] [d/l]
Re^5: Extract Multiple Lines from the End of a multi-line string by ikegami (Patriarch) on Oct 17, 2008 at 16:58 UTC
Presumably followed by `\z`? Your last line doesn't end with `\n`, and that's a bad use of capturing parens.	[reply] [d/l] [select]
Re^6: Extract Multiple Lines from the End of a multi-line string by NateTut (Deacon) on Oct 17, 2008 at 17:03 UTC
Re^7: Extract Multiple Lines from the End of a multi-line string by ikegami (Patriarch) on Oct 17, 2008 at 17:09 UTC
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