Question

I have a string in Perl like: “Full Name (userid)” and I want to return just the userid (everything between the “()“‘s).

What regular expression would do this in Perl?

Answer 1

This will match any word (\w) character inside of “(” and “)“

\w matches a word character (alphanumeric or _), not just [0-9a-zA-Z_] but also digits and characters from non-roman scripts.

my($username) = $str =~ /\((\w+)\)/;
# or
$str =~ /\((\w+)\)/;
my $username  = $1;

If you need it in a s///, you can get at the variable with $1 or \1.

$str =~ s/\((\w+)\)/$1:\1/; # pointless example

If you want to capture all possibilities these would work better:

my($username) = $str =~ /\(([^\)]+)\)/;
# or
my($username) = $str =~ /\((.+?)\)/;

If your regexp starts to get complicated, I would recommend you learn about the /x option.

my($username) = $str =~ / \(  ( [^\)]+ )  \) /x;

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Please see perldoc perlre, for more information.

If you are just beginning to learn regexps, I would recommend reading perldoc perlretut.