What's the Size of a Boolean Variable (bool) in C ?

Determining the Size of 'bool' in C

The C standard does not explicitly define the size of the 'bool' data type. This means that the size of 'bool' is left to the implementation of the compiler.

Implementation-Defined Size

The C language standard states that the size of any fundamental type, except for 'char', 'signed char', and 'unsigned char', is implementation-defined. This includes the 'bool' data type. Therefore, the size of 'bool' can vary depending on the compiler being used.

Further Clarification

In §5.3.3/1 of the C standard, it is explicitly stated that "the result of sizeof applied to any other fundamental type is implementation-defined." Footnote 69 further emphasizes this point by stating that "sizeof(bool) is not required to be 1."

Conclusion

The size of 'bool' in C is not guaranteed to be 1. It is an implementation-defined characteristic, which means that its size can vary depending on the compiler.

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