Is sizeof(bool) defined in the C++ language standard?

c++ boolean sizeof implementation-defined-behavior
0xbadf00d picture 0xbadf00d · Feb 4, 2011 · Viewed 76.5k times · Source

I can't find an answer in the standard documentation. Does the C++ language standard require sizeof(bool) to always be 1 (for 1 byte), or is this size implementation-defined?

Answer

GManNickG picture GManNickG · Feb 4, 2011

sizeof(bool) is implementation defined, and the standard puts notable emphasis on this fact.

§5.3.3/1, abridged:

sizeof(char), sizeof(signed char) and sizeof(unsigned char) are 1; the result of sizeof applied to any other fundamental type is implementation-defined. [Note: in particular, sizeof(bool) and sizeof(wchar_t) are implementation-defined.69)]

Footnote 69):

sizeof(bool) is not required to be 1.

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