this post was submitted on 31 Aug 2024
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The C Programming Language

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Are there better alternatives to null-terminated strings? (lemmy.ml)
submitted 3 weeks ago by [email protected] to c/[email protected]
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[โ€“] [email protected] 3 points 3 weeks ago (1 children)

No, I am interested in only implementations. I've come across a few such, for example:

  • the Pascal string (also probably known as the 2-byte length string)
  • the alt-byte terminated (used by CDC and ZX80)
  • the bit method (in pre-60s era mainframes)
  • the record method (aka the struct method you were talking about, which is probably the default C++/Rust implementation), etc.

Are there any other custom data structures that are faster and also at the same time safer than the default? What about ropes?

[โ€“] [email protected] 2 points 3 weeks ago* (last edited 3 weeks ago)

CBOR uses variable-sized length prefixes. Strings zero to 23 bytes long require just one byte of overhead, after that it becomes two bytes for strings up to length 255, and 3 bytes of overhead for strings up to 65535. Above that, it requires 5 bytes of overhead, which is probably enough for strings up to at least a few hundred GB, though I didn't test that far.

click to see how i empirically determined those numbers$ python -c 'import cbor; overhead=0; print({ length:overhead for length in range(65537) if overhead < (overhead:=len(cbor.dumps("a"*length))-length) })'

{0: 1, 24: 2, 256: 3, 65536: 5}