In article <4988d2fa997f8_8527a9e32018e7 / redmine.ruby-lang.org>,
  Michael Selig <redmine / ruby-lang.org> writes:

> I have a simple use-case:
>
> Existing datafile has fixed length records, currently single-byte chars. I want to convert the application (which is quite old) to support multi-byte characters, but I don't want to have to go to the trouble of changing to variable-length or delimited records/fields. I would like to be able to read each record (whose length in chars I know) with one operation, instead of looping through each character.

Fixed length characters needs variable length bytes in multibyte encoding.

So the record is variable length in byte layer.  Is it ok?  

In such format, record-wise update cannot be implemented efficiently.
-- 
Tanaka Akira