C++ proposal: There are exactly 8 bits in a byte

Original Article ↗ Hacker News Discussion ↗

A new C++ standards proposal would formally require that a byte always be 8 bits, aligning the language with how virtually all modern hardware and software already behave. Commenters largely welcome the change as a practical cleanup, noting that most real-world code implicitly assumes 8-bit bytes and that similar moves (like mandating two’s-complement integers) have already been made. Critics worry it further marginalizes exotic or legacy architectures (such as certain DSPs and historical mainframes) that use non‑8‑bit addressable units, raising questions about how far standards should go in codifying de facto realities.

Motivation and Practical Reality

  • Many commenters note that virtually all modern systems already use 8‑bit bytes, and large amounts of C/C++ code implicitly assume this.
  • Several argue that formalizing CHAR_BIT == 8 simply matches de‑facto reality and improves developer expectations and portability in practice.
  • Others point out they only recently learned that byte was not guaranteed to be 8 bits, and see this as a surprising and confusing corner of the standard.

Legacy and Exotic Architectures

  • Multiple examples of non‑8‑bit “bytes” are discussed: 6‑, 7‑, 9‑, 10‑, 12‑, 16‑, 24‑, 32‑, and 36‑bit addressed units (UNIVAC, PDP‑10, various DSPs, historical mainframes, retro consoles).
  • Some of these systems still exist as emulated mainframes or niche DSPs, but often don’t track modern C++ standards or run mostly non‑C++ code.
  • A few participants enjoy hardware diversity and are sad to see standards drop support for such machines, even if they’re niche.

DSPs and Word‑Addressed Systems

  • DSP chips with 16‑ or 32‑bit addressable units are repeatedly cited as the only current plausible targets that conflict with CHAR_BIT == 8.
  • Opinions diverge: some say these platforms are specialized enough that non‑standard or frozen C/C++ dialects are acceptable; others insist they remain “real” systems that will lose conformance.

Portability vs. Simplification

  • Supporters frame the change as analogous to mandating two’s complement integers: reflect how “every real computer works now,” and reduce undefined edge cases.
  • Critics worry about excluding legitimate architectures and question the concrete benefit, since CHAR_BIT would still exist and much code already assumes 8.
  • Some see this as part of C++’s tension between maximal portability and acknowledging the practical hardware baseline.

Terminology and Related Debates

  • Several comments clarify: in C/C++ a “byte” is the size of char; “octet” is the unambiguously 8‑bit term, especially in networking.
  • There is side discussion about the fuzziness and obsolescence of “word” size, and about whether higher‑level code should think in bits, bytes, or fixed‑width integer types.