Hans, got it: /x tells sys' to ignore all white space, not just \n. thanks very much. and thanks to the people who make possible this great mailing list. ;o)
tom arnall north spit, ca On Friday 31 March 2006 07:29 am, Hans Meier (John Doe) wrote: > tom arnall am Freitag, 31. März 2006 09.56: > > i need the blank in 'From [' etc in order to distinguish it from the > > strings with 'From:' one solution to the problem, btw, is to use '\s' > > instead of a literal blank. does this behavior rank as a bug in perl? > > No, absolutely not. > > To make your distiction, you *have* to use the \s with the /x modifier; > without, you can use either. > > The /x modifier's aim is to allow readable *formatting* of complex regexes > with spaces, line brakes, comments (#). ' ' in this case is irrelevant for > the matching. Look at the beginning of > > perldoc perlre > > hth! > > Hans > > [bottom post order:] > > > On Thursday 30 March 2006 05:15 am, Hans Meier (John Doe) wrote: > > > tom arnall am Donnerstag, 30. März 2006 12.36: > > > > the following code: > > > > > > > > my (@main); > > > > $_=" > > > > From a > > > > From: b > > > > From: c > > > > From: d > > > > "; > > > > @main = /From [^\n]*?\n.*?(From: .*?\n).*?/gx; > > > > print "@main"; > > > > print "------------------------------\n"; > > > > @main = /From [^\n]*?\n.*?(From: .*?\n).*?/g; > > > > print "@main"; > > > > > > > > produces: > > > > > > > > From: b > > > > From: d > > > > ------------------------------ > > > > From: b > > > > > > > > the only difference between the two regex lines is the 'x' after '/g' > > > > in the first of the two regex lines. > > > > > > indeed :-) > > > > > > And your question could be: Why does this produce different results? > > > > > > There's an additional difference on the semantic level: spaces in the > > > 1st regex are irrelevant. Look at the first regex space: in the 2nd > > > regex, it matches (only) in "From a", but not in "From: c", whereas the > > > 1st regex matches "From a" *and* "From: c". > > > > > > /From[^\n]*?\n.*?(From: .*?\n).*?/gx; > > > and > > > /From[^\n]*?\n.*?(From: .*?\n).*?/g; > > > produce both the same output. > > > > > > hth! > > > Hans -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] <http://learn.perl.org/> <http://learn.perl.org/first-response>
