Ordering of boolean values

Question

Under C++ or from C99, how is the less-than operator < defined for boolean values?

Alternatively, explain the behaviour of

Answer 1

This makes perfect sense. The integral type => bool conversion is effectively b = i != 0. In order to do the < comparison it promotes the bool to int by the rule false=>0 and true=>1. In your first case -1 will equate to true, and both will promote to 1 so it's false. Obviously 1 is never less than 0 for the second and third cases, while 0 < 1 in the last case.