extract range from array of data

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

Howdy everyone and merry perlmass! blah.txt contains the following data:

junk junk
junk junk
start
not junk
not junk
end
junk junk
[download]

more junk

open (hFile, "blah.txt");
@d = <hFile>;
close hFile;
[download]

now how would i extract only:

start
not junk 
not junk
end
[download]

from that array? thanks all :) I have looked around, all i can find is how to do this on a string, but then i risk loosing all the nowlines. p.s: would be better if this was possible in 1 line

Comment on extract range from array of data Select or Download Code

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Re: extract range from array of data by BrowserUk (Patriarch) on Dec 26, 2015 at 12:04 UTC
Use the flip-flop operator: `@d = grep{ /^start$/ .. /^end$/ } <hFile>;` [download] With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". I knew I was on the right track :) In the absence of evidence, opinion is indistinguishable from prejudice.	[reply] [d/l]
Re^2: extract range from array of data by QuillMeantTen (Friar) on Dec 26, 2015 at 12:45 UTC
BrowserUK you just blew my mind, thanks for the tip!	[reply]
Re^2: extract range from array of data by theleftright (Novice) on Dec 26, 2015 at 13:06 UTC
thanks (y) perfect.	[reply]
Re: extract range from array of data by QuillMeantTen (Friar) on Dec 26, 2015 at 12:44 UTC
Greetings, First, loading it all inside an array might not be a good idea, if its a very large file you are asking for trouble, why not read it line by line until you reach start, save the lines until you read end and close the file at that time?	[reply]
Re^2: extract range from array of data by AnomalousMonk (Archbishop) on Dec 26, 2015 at 21:57 UTC
There's a discussion of this approach in perlfaq6: "How can I pull out lines between two patterns that are themselves on different lines?" — even a one-liner! See also the discussion of the scalar context `..` flip-flop operator in Range Operators (scalar context sub-section) in perlop (some examples of what you want there also). (Update: See also Flipin good, or a total flop?, also with code that's almost exactly what theleftright seems to want.) Give a man a fish: `<%-{-{-{-<`	[reply] [d/l] [select]