Re: Split a string based on change of character

I don't know if you can use a split here, because your pattern may not consume characters to achieve what you want.

I've tried this one: m/((?<=.))(?!\1)/ which should be "a position before which there is a character, and after that a different character", but it doesn't work.

Can anybody tell me why this doesn't match the string 'aaabbbc'?

Update: Zoffix told me on IRC that the right thing would be m/(?<=(.))(?!\1)/ (because the assertion is zero-width), however that doesn't work in split as well, because it returns the captured character:

$ perl -MData::Dumper -wle '$Data::Dumper::Indent=0; $_="aaabbc"; prin
+t Dumper([split m/(?<=(.))(?!\1)/]);'
$VAR1 = ['aaa','a','bb','b','c','c'];
[download]

This way you had to discard every second item of the returned list - not pretty either ;-)

Perl 6 in German

Comment on Re: Split a string based on change of character Select or Download Code

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Re^2: Split a string based on change of character by Skeeve (Parson) on Jul 28, 2007 at 13:16 UTC
You can use split: `my $string= 'AAABBBCCCDD'; my $i=0; my @words= grep $i=!$i,split /(?<=(.))(?!\1)/,$string; print join "\n",@words,'';` [download] `s$$([},&%#}/&/]+}%&{});#$&&s&&$^X.($'^"%]=\&(\|?{%` `+`.+=%;.#_}\&"^"-+%*).}%:##%}={~=~:.")&e&&s""`$''`"e	[reply] [d/l] [select]
Re^3: Split a string based on change of character by ikegami (Patriarch) on Jul 28, 2007 at 15:02 UTC
I never thought of `grep $i=!$i,` [download] before. I usually use `grep $i^=$i,` [download] Yours is easier to understand, though. Update: Yeah, I mean `grep $i^=1,`.	[reply] [d/l] [select]
Re^4: Split a string based on change of character by Skeeve (Parson) on Jul 28, 2007 at 15:28 UTC
But `$i^=$i` makes $i 0 at once. So it's different to `$i=!$i` Back in the ancient times of C64 Basic I used `j=1-j` `s$$([},&%#}/&/]+}%&{});#$&&s&&$^X.($'^"%]=\&(\|?{%` `+`.+=%;.#_}\&"^"-+%*).}%:##%}={~=~:.")&e&&s""`$''`"e	[reply] [d/l] [select]
Re^5: Split a string based on change of character by eyepopslikeamosquito (Archbishop) on Jul 29, 2007 at 02:43 UTC
Re^3: Split a string based on change of character by eyepopslikeamosquito (Archbishop) on Jul 28, 2007 at 23:47 UTC
As you might expect, I was tempted to (ab)use the magical $\| flip-flop variable: `my @words = grep --$\|, split /(?<=(.))(?!\1)/, $string;` [download] but was able to restrain myself. :-)	[reply] [d/l]
Re^2: Split a string based on change of character by Anonymous Monk on Jul 28, 2007 at 08:37 UTC
`<Zoffix> eval: $_='zyxxaabbbcccccc'; push @a, $1 while s/((.)\2*)//;[@ +a] <_ZofBot> Zoffix: ['z','y','xx','aa','bbb','cccccc']` [download] 20070730 Janitored by Corion: Added code tags, as per Writeup Formatting Tips	[reply] [d/l]
Re^3: Split a string based on change of character by Anonymous Monk on Jul 28, 2007 at 08:43 UTC
Or even: $_='zyxxaabbbcccccc'; push @a, $1 while /((.)\2*)/g; Which doesn't destroy original data.	[reply]