Regex Help Please?

I am a newbie at RegEx, and was wondering if someone could help me with this little problem.

I have a variety of field names in camel casing:

fieldName

fieldNameAndSomethingElse

etc, etc.

I need to convert them to underscore separated name like so:


field_name

field_name_and_something_else

etc, etc.

Can I do this with regex? How would I?

s/\([a-z]\)\([A-Z]\)/\1_\2/g

Sorry, should be:

s/\([a-z]\)\([A-Z]\)/\1_\L\2/g

Thanks a bunch!

s/\([a-z]\)\([A-Z]\)/\1_\2/g
[/b]

Thanks.