split on newline

tbone654 has asked for the wisdom of the Perl Monks concerning the following question:

I am looking for a "smooth" way to modify the code I'm simulating below... I read in a file "line-by-line" to an array and split on newline, leaving just the value of the line without the \n ... So I can create a delimited line of several items... first example
Where I get in trouble is where a line read in is blank, which shifts everything to the left in the output (notice the rogue ; at the end) because splitting on the newline leaves an empty entry... second example
I can check for an empty line and put a space in there which works, but it's just not sexy... third example

$ perl -e 'BEGIN{@words = ("one\n","two\n","three\n","four\n","five\n"
+,"six\n",)} $a=0;printf("%s;%s;%s;%s;%s;%s\n",(split/\n/,@words[$a]),
+(split/\n/,@words[$a+1]),(split/\n/,@words[$a+2]),(split/\n/,@words[$
+a+3]),(split/\n/,@words[$a+4]),(split/\n/,@words[$a+5])       );'

one;two;three;four;five;six

$ perl -e 'BEGIN{@words = ("one\n","two\n","three\n","\n","five\n","si
+x\n",)} $a=0;printf("%s;%s;%s;%s;%s;%s\n",(split/\n/,@words[$a]),(spl
+it/\n/,@words[$a+1]),(split/\n/,@words[$a+2]),(split/\n/,@words[$a+3]
+),(split/\n/,@words[$a+4]),(split/\n/,@words[$a+5])       );'  

one;two;three;five;six;

perl -e 'BEGIN{@words = ("one\n","two\n","three\n"," \n","five\n","six
+\n",)} $a=0;printf("%s;%s;%s;%s;%s;%s\n",(split/\n/,@words[$a]),(spli
+t/\n/,@words[$a+1]),(split/\n/,@words[$a+2]),(split/\n/,@words[$a+3])
+,(split/\n/,@words[$a+4]),(split/\n/,@words[$a+5])       );'

one;two;three; ;five;six
[download]

I've been messing with this for 2 days now, and I'm wondering if anyone has a different way of thinking to share?

tia

Comment on split on newline Download Code

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Re: split on newline by ikegami (Patriarch) on Sep 12, 2014 at 19:06 UTC
`my @words = <>; chomp(@words); print(join(';', @words), "\n");` [download] As a one-liner: `perl -nle'push @w, $_; END { print join ";", @w }'` [download] `-l` inserts a `chomp;` into `-n`'s (and `-p`'s) loop.	[reply] [d/l] [select]
Re^2: split on newline by tbone654 (Beadle) on Sep 12, 2014 at 20:02 UTC
That works... the -l is the secret, thank you... I was chomp'ing it manually yesterday and it was blowing up...	[reply]
Re^3: split on newline by ikegami (Patriarch) on Sep 13, 2014 at 00:29 UTC
It's not the chomping that was blowing up your code. `perl -nle' push @w, $_; END { print join ";", @w } '` [download] is the same as `perl -ne' BEGIN { $\ = "\n"; } chomp; push @w, $_; END { print join ";", @w } '` [download]	[reply] [d/l] [select]
Re^3: split on newline by AnomalousMonk (Archbishop) on Sep 12, 2014 at 20:30 UTC
You had some other problem yesterday. chomp-ing 'manually' won't blow anything up.	[reply]
Re: split on newline by Laurent_R (Canon) on Sep 12, 2014 at 21:32 UTC
Although ikegami has provided a much shorter and better solution, I would like to come back to your very complicated syntax and suggest some possible improvements to the rest of your code. Using `chomp`, you could do this: `$ perl -e '@words = ("one\n","two\n","three\n","four\n","five\n","six\ +n",); chomp @words; print join";", @words;' one;two;three;four;five;six` [download] Although I would not really recommend this, you could also use `split` if you really wanted to: `$ perl -e '@words = ("one\n","two\n","three\n","four\n","five\n","six\ +n",); @words = map {split /\n/, $_ } @words; print join";", @words;' one;two;three;four;five;six` [download] Or perhaps a regex: `$ perl -e '@words = ("one\n","two\n","three\n","four\n","five\n","six\ +n",); @words = map {s/\n//; $_} @words; print join";", @words;' one;two;three;four;five;six` [download] Or `split` again, but without a `map` this time: `$ perl -e '@words = ("one\n","two\n","three\n","four\n","five\n","six\ +n",); $_ = (split /\n/)[0] for @words; print join";", @words;' one;two;three;four;five;six` [download] Or, if you don't want to use the `join` function: `$ perl -E '@words = ("one\n","two\n","three\n","four\n","five\n","six\ +n",); local $" = ";"; $_ = (split /\n/)[0] for @words; say "@words";' one;two;three;four;five;six` [download] Well, I could probably offer at least a dozen other solutions mixing the various ideas above or introducing new ones, but I hope you get the idea of how to do the things in a much more concise way than what you had.	[reply] [d/l] [select]
Re^2: split on newline by johngg (Canon) on Sep 12, 2014 at 22:24 UTC
You could save yourself some typing when initialising `@words` by using a HEREDOC and split with a look-behind. `$ perl -Mstrict -Mwarnings -E ' my @words = split m{(?<=\n)}, <<EOL; one two three EOL say qq{$_-----} for @words;' one ----- two ----- three ----- $` [download] So, taking the whole thing together. `$ perl -Mstrict -Mwarnings -E ' say join q{;}, map { chomp; $_ } split m{(?<=\n)}, <<EOL; one two three EOL' one;two;three $` [download] I hope this is of interest. Update: Removed the `$PS2` prompts fromthe second example for easier copy'n'paste. Cheers, JohnGG	[reply] [d/l] [select]