Standard library header <cstdbool>

From cppreference.com
< cpp‎ | header
 
 
 

This header was originally in the C standard library as <stdbool.h>.

Compatibility header, in C defines true, false and bool which are keywords in C++.

__bool_true_false_are_defined
(C++11)
C compatibility macro constant, expands to integer constant 1
(macro constant)