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.