what does the signed/unsigned comparison warning mean?

Question

auto.cpp: In function ‘int autooo(unsigned int)’:
auto.cpp:33:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]

Answer 1

It says you are comparing two different things. Most notably the range of one does not fit into the range of another.

I.e there. Exists a number in the unsigned range that cannot be expressed as a signed number