Boolean type (stdbool.h)

Include stdbool.h for the C99 boolean spelling used by many portable C programs.

Types and Macros

Name	Meaning
bool	Boolean storage type.
true	Boolean true value.
false	Boolean false value.
__bool_true_false_are_defined	C99 feature-test macro for bool, true, and false.

Runtime model

DCC C Compiler recognizes the native C99 _Bool keyword as a first-class 1-byte scalar type. This header only provides the portable names: bool is _Bool, true is 1, and false is 0.

Assignments, casts, initializers, parameter loads, and return values normalize nonzero _Bool / bool values to 1.

Boolean values

Relational and logical operators already produce 0 or 1, so they are the cleanest way to assign boolean state:

#include <stdbool.h>

bool ready = false;

ready = (count > 0);
if (ready)
    puts("go");

__bool_true_false_are_defined is provided for source compatibility with code that checks whether stdbool.h has supplied the standard names.