Issue
I've noticed that the Linux kernel code uses bool, but I thought that bool was a C++ type. Is bool a standard C extension (e.g., ISO C90) or a GCC extension?
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Solution
bool exists in the current C - C99, but not in C89/90.
In C99 the native type is actually called _Bool, while bool is a standard library macro defined in stdbool.h (which expectedly resolves to _Bool). Objects of type _Bool hold either 0 or 1, while true and false are also macros from stdbool.h.
Note, BTW, that this implies that C preprocessor will interpret #if true as #if 0 unless stdbool.h is included. Meanwhile, C++ preprocessor is required to natively recognize true as a language literal.
Answered By - AnT stands with Russia Answer Checked By - Marilyn (WPSolving Volunteer)