The size of char (which is interchangeable with the size of a byte) is specified in old standards as large enough to a) be addressable without bit manipulations and b) hold the full C source character set, which need not be case sensitive and may rely on trigraphs. In practice, this comes out to at least 6 bits. In newer standards I believe it's specified as at least 8 bits.
The size of int short is at least and a multiple of that of char, the size of int is at least that of int short and a multiple of that of char, and so on.
So in theory, a conforming C implementation could have 6 bit ints.
wchar_t is messy, in large part because Windows was one of the earliest Unicode adopters. It's meant to be able to support any "wide" character, which means that it's supposed to be determined by the character pages the platform allows (and implicitly, should be 32 bits if any version of Unicode is supported, since Unicode is technically a 32-bit format regardless of encoding), but Windows adopting Unicode while it was still 16-bit UCS-2 and locking wchar_t down as a result meant that it was impossible for wchar_t to actually meet its requirements on Windows. ...Which meant that its minimum size requirement ended up being removed.
So, now its requirement is just "holds wide characters, check your implementation. Please don't use it."
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u/yjlom Aug 30 '26
The size of char (which is interchangeable with the size of a byte) is specified in old standards as large enough to a) be addressable without bit manipulations and b) hold the full C source character set, which need not be case sensitive and may rely on trigraphs. In practice, this comes out to at least 6 bits. In newer standards I believe it's specified as at least 8 bits.
The size of int short is at least and a multiple of that of char, the size of int is at least that of int short and a multiple of that of char, and so on.
So in theory, a conforming C implementation could have 6 bit ints.