Selective character count (only non-alphanumeric)? Challenge (Easy)


  Write a function which takes an argument and returns the number of non-alphanumeric characters found.


Challenge (Hard)


  Write a function which takes an argument and returns the number of bytes used to store the number of non-alphanumeric characters found.  (ie: include calculation for multi-byte characters.)


Rules / Notes


Alphanumeric in this case is defined as:

abcdefghijklmnopqrstuvwxyz
ABCDEFGHIJKLMNOPQRSTUVWXYZ
0123456789
A null character should count as 0 characters, but as 1 byte when stored.

NUL
Showing multi-byte support (if too complicated) only has to demonstrate one character set or language reference / codepage (if this actually matters.  I don't know, so just putting it out there.)


Winner

Since this is code golf, the shortest code that correctly matches the challege wins.
Perl, 14 characters

y/A-Za-z0-9//c