regex square brackets exceptions

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

Twas reading about java regex and noticed they had a section in the article about Character Classes using [] characters...

[a-z-[bc]] = a through z, except for b and c: [ad-z] (subtraction)
[a-z-[m-p]] = a through z, except for m through p: [a-lq-z]
[a-z-[^def]] = d, e, or f

I'd never seen square brackets used with such... abandon... and wondered if Perl had an equivalent way of doing such exceptions...

I tried the equivalent in Perl, but it didn't appear to match as they indicate from the Java world.

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Re: regex square brackets exceptions by moritz (Cardinal) on Jun 21, 2011 at 13:59 UTC
There's an easy way to check: try it out. There's another one that I like: `$ perl -Mre=debug -ce '/[a-z-[bc]]/' Compiling REx "[a-z-[bc]]" Final program: 1: ANYOF[\-[a-z][] (12) 12: EXACT <]> (14) 14: END (0) anchored "]" at 1 (checking anchored) stclass ANYOF[\-[a-z][] minlen 2 -e syntax OK Freeing REx: "[a-z-[bc]]"` [download] It tells you that the final closing square bracket is interpreted as a literal (EXACT) match, so it surely didn't parse the regex class the same way as Java does. Perl 6 - second systems done right	[reply] [d/l]
Re: regex square brackets exceptions by ww (Archbishop) on Jun 22, 2011 at 00:40 UTC
Are these acceptably comparable? They don't use a single bit of syntax, of course, but it's not clear to me from your question if you're seeking syntax or simply an method to exclude characters. `perl -e "use 5.012; my $foo='now is the time for'; if ( $foo =~ /[meit +]+/ && $foo =~ /[^a]{1,20}/ ) { say 'true';} else {say 'nope';}" true` [download] Similarly, not a single phrase, but... `perl -e "use 5.012; my $bar = 'abcdefg'; if ($bar =~ /[a-d]/ && $ bar +!~ /[ef]/ ){ say 'true';} else {say 'false';}" false` [download]	[reply] [d/l] [select]
Re: regex square brackets exceptions by Nikhil Jain (Monk) on Jun 21, 2011 at 13:22 UTC
Have a look at perlrequick:character classes , you will come to know to how to write character class in Perl.	[reply]
Re^2: regex square brackets exceptions by raybies (Chaplain) on Jun 21, 2011 at 13:36 UTC
Actually I was already familiar with character classes as per that documentation... I'm teaching regex, and am interested in the differences between Perl and Java because I've got java programmers in the audience. Perl being what it is... one never knows if there isn't some little bit of syntactic sugar hidden away somewhere... But the short answer is, "No."	[reply]


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