Char或Int表示C中的布尔值？

Question

I find that there is no native bool type. People either use int or char - though it seem that int might be more frequently used than char ? Is this true?

My first impulse was to use char as it is a smaller data type, but there something I've missed? Is int better for boolean values, and if so - why?

Answer 1

There is a _Bool in C99 , and a bool if you include stdbool.h .

If you don't have it (a decently modern compiler), use int , it's usually the fastest type. The memory savings of using char are likely negligible.

Answer 2

If you're using a reasonably modern C compiler then you just need:

#include <stdbool.h>

This typically has a macro such as:

#define bool _Bool

which lets you use C99's built-in _Bool type wherever you need a bool .

Answer 3

There is a native type named _Bool (starting with C99). In <stdbool.h> , there's also a #define to provide bool as an alias, if you want it (also has #define s for true and false ).

Answer 4

According to ISO-9899 the result of relation, logical and equality operators has type int . true and false from stdbool.h are also integers. If you want to spare memory - use bit-fields.

Answer 5

Actually there's no real difference since char gets always promoted to int when using it (check this ). I have never seen a char used as a bool though, so I'd go for using an int.