TTF_RenderUTF8 with non-UTF8 character

Hello,

I'm just wondering why TTF_RenderUTF8 does not support printing 
characters that are not (I support UTF8).

My problem, I used gettext to write some french on my screen, my drawing 
functions always use TTF_RenderUTF8 and it works, my text that
contains some accents like 'é' 'ç' 'à' are written correctly.

However, if I wait for user input, I try to fill a char buffer and print 
it on the screen (e.g let the user write his name).

So I read the SDL_keysym unicode member and add it to the buffer, but 
then when using TTF_RenderUTF8, the output is broken, only squares are 
written (like missing characters)..

In fact, when I press a key like 'a', 'b' the unicode member will be set 
to the ASCII character (normal) but it will also set it for 'é' which 
value is 233, that's probably why I get a bad font rendering.

Please try my source code just below, put this font directly in the same 
directory as the executable:

-- font --
http://markand.malikania.fr/DejaVuSans.ttf

-- code --
#include <stdio.h>
#include <stdbool.h>
#include <err.h>