How to extract all alphanumeric characters from a string?

[biswanath_c]

I'd like to extract all alphanumeric characters from a given string and store them into another string. How can i achieve this?

[ikegami]

utf8::upgrade( my $alphanums = $chars );
$alphanums =~ s/[\W_]//g;

or

( my $alphanums = $chars ) =~ s/\P{Alnum}//g;

utf8::upgrade makes /\w/ match alphanums and "_", and /\W/ everything else.

Update: The original solution didn't remove underscores. Fixed.
Update: Added alternative method.