“$ ^ N”和“$ +”之间有什么区别？

Question

有人能告诉我一个例子，它展示了这两个变量的不同行为（$ ^ N和$ +）？

Answer 1

From perldoc perlvar :

$+ : The text matched by the last bracket of the last successful search pattern.

versus

$^N : The text matched by the used group most-recently closed (ie the group with the rightmost closing parenthesis) of the last successful search pattern.

This should illustrate the difference:

#!/usr/bin/perl

use strict; use warnings;

my $s = '12345';

if ( $s =~ /(1([0-9]))/ ) {
    print "$_\n" for $+, $^N;
}

Output:

2
12