I wrote in my Matlab files my comments in French and the police of
writing in Octave does not take into account the French characters like
é,è,, ç, ù ê. Do you know what I can do so that the French police is taken
in count? (I remarked that with Octave 4.4.0 under Windows, this problem is
fixed but I have only Linux Mint 18.3 and Ubuntu V18.)
Matlab (and Octave) uses the system code page when saving .m files. For
Windows the system code page depends on the localization you are using. For
a French version of Windows that should be "ISO 8859-15". For Linux the
system code page is (almost) always UTF-8 independent of any localization.
What you could do: open your .m files in an external Editor (Notepad++ for
example) and save them with UTF-8 encoding (no BOM). After that the French
characters should display fine in Octave on Linux.
If you don't care for Matlab, you can set up your Octave on Windows to also
use UTF-8 in the Editor preferences.