Does it true that c does not support boolean value by default?

Question

Yes, c has defines a header file stdbool.h for bollean expression. But I think we can also using boolean variables or bollean expressions without enclise stdbool.h.

Answer 1

Well, have you considered actually trying it?

https://stackoverflow.com/questions/1921539/using-boolean-values-in-c#1921557

Answer 2

https://en.cppreference.com/w/c/language/bool_constant