C99 standard. stdbool.h
C99 standard defined booleans in C, by using stdbool.h header.
This header defines:
- bool type
- true expands to 1
- false expands to 0
If you set a bool variable to a value different from zero it is automatically assigned to one.
If you do use a former standard you can use an integer like a boolean: 0 equals false and other value equals true.
or use a trick:
typedef enum { false, true } bool;Some guidelines to use booleans:
- Do not compare against true, false, zero, etc:
- Give positive names to boolean variables
- Avoid booleans in function arguments.
e.g:
bool foo;
...
if (foo == true) (BAD)
if (foo == 1) (BAD)
if (foo) (GOOD)
if (foo == false) (BAD)
if (!foo) (GOOD)It becames difficult to read.
(BAD)
bool not_done;
if(!not_done)
(GOOD)
bool done;
if (done)
It becames difficult to understand argument meaning in function calls.
int foo(bool option);
foo(true);
REFERENCE
stdbool.h
Using Booleans in C (Stack Overflow)