On Sun, Apr 13, 2008 at 4:03 AM, <[EMAIL PROTECTED]> wrote: > > > my $count = () = $str =~ /a/g; > > > Thanks Chas. Owens, > I need some explanation on the above on how the above regex count the > number of 'a' in a string. > > With my limited understanding, this is what I thought:- > $count = () ; #To me it means $count is assigned with a undefined value > which is then assigned with a value of $str > To me $str=~/a/g is a matching test, if it match it will be 1 and if > unmatched will be 0. snip
The match operator with option g returns different things based on its context: #!/usr/bin/perl use strict; use warnings; my $scalar = "aaaba" =~ /a/g; my @list = "aaaba" =~ /a/g; my $list_then_scalar = () = "aaaba" =~ /a/g; print "scalar: $scalar list: @list list then scalar: $list_then_scalar\n"; In scalar context it returns true if it matches at all and in list context it returns a list of matches. Now, normally a list in scalar context returns the last element of the list, but if you evaluate the list in list context and then in scalar context you instead get the number of items in the list (similar to how an array acts in scalar context). -- Chas. Owens wonkden.net The most important skill a programmer can have is the ability to read. -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] http://learn.perl.org/
