Eli Zaretskii <eliz@gnu.org> writes:
>> 
>> > Yes, I propose that the current behavior wrt the argument will be left
>> > unchanged, except when the argument is zero, i.e. "C-u 0".
>> 
>> Currently, zero also means no truncation, keeping that meaning seems
>> important too.  Perhaps a negative argument would be a better choice?
>
> Yes, that'd be fine with me.  Thanks.

I added `-' to echo in character format, and `-1' to print it to the
buffer.  I split the patch in 2 parts, the first just refactors the
printing code, the 2nd adds the new behaviour.