How do I use perl regex to extract the digit value from '[1]'?

Question

My code...

$option = "[1]";
if ($option =~ m/^\[\d\]$/) {print "Activated!"; $str=$1;}

I need a way to drop off the square brackets from $option. $str = $1 does not work for some reason. Please advise.

Answer 1

要获得1美元的工作，您需要使用括号捕获括号内的值，即：

if ($option =~ m/^\[(\d)\]$/) {print "Activated!"; $str=$1;}

Answer 2

if ($option =~ m/^\[(\d)\]$/) { print "Activated!"; $str=$1; }

Or

if (my ($str) = $option =~ m/^\[(\d)\]$/) { print "Activated!" }

Or

if (my ($str) = $option =~ /(\d)/) { print "Activated!" }

..and a bunch of others. You forgot to capture your match with ()'s .

EDIT:

if ($option =~ /(?<=^\[)\d(?=\]$)/p && (my $str = ${^MATCH})) { print "Activated!" }

Or

my $str;
if ($option =~ /^\[(\d)(?{$str = $^N})\]$/) { print "Activated!" }

Or

if ($option =~ /^\[(\d)\]$/ && ($str = $+)) { print "Activated!" }

For ${^MATCH}, $^N, and $+, perlvar .

I love these questions : )