What version of 5.16 are you using, and what OS? It worked fine for me.

[~]$ perl -v

This is perl 5, version 16, subversion 3 (v5.16.3) built for x86_64-li
+nux
(with 1 registered patch, see perl -V for more detail)

Copyright 1987-2012, Larry Wall

Perl may be copied only under the terms of either the Artistic License
+ or the
GNU General Public License, which may be found in the Perl 5 source ki
+t.

Complete documentation for Perl, including FAQ lists, should be found 
+on
this system using "man perl" or "perldoc perl".  If you have access to
+ the
Internet, point your browser at http://www.perl.org/, the Perl Home Pa
+ge.

[~]$ perl -de1

Loading DB routines from perl5db.pl version 1.37
Editor support available.

Enter h or 'h h' for help, or 'man perldebug' for more help.

main::(-e:1):   1
  DB<1> $_ = '1223w3433.45+34'

  DB<2> x /\d\D*/g
0  1
1  2
2  2
3  '3w'
4  3
5  4
6  3
7  3.
8  4
9  '5+'
10  3
11  4
  DB<3>
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