Standard library header <cstdbool>, <stdbool.h>

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++.

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

Notes

<cstdbool> is deprecated in C++17 and removed in C++20. Corresponding <stdbool.h> is still available in C++20.