So do signed types (guaranteed to be 2's complement since C23, though all sane targets have been using that representation for a long time).
replyTwo's complement encodes -x as ~x + 1 = 2^n - x = -x (mod 2^n) and can therefore be mixed with unsigned for (+, -, *, &, |, ^, ~, <<).
> I think they should be used exclusively when this is needed
The opposite: signed type usage should be kept to a minimum because signed type (and pointer) overflow is UB and will get optimized as such.
For signed types you can can also get a run-time trap on overflow, making it safe to use. Bug caused by unsigned wraparound are extremely hard to find.
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replyyeah unsigned are really about opting to perform modular arithmetic, or for mapping hardware registers.
replyC is weakly typed, the basic types are really not to maintain invariants or detect their violation
If you need saturating arithmetic, C23 adds that as well with a new header:
https://en.cppreference.com/w/c/header/stdckdint
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