3 ms·

> This is false; the encoding of codepoint 0 is 0x00 per the standard Well, yes. That's the point: 0x00 is only ever used to encode codepoint 0. It never shows

by derleth 13y ago

> This is false; the encoding of codepoint 0 is 0x00 per the standard Well, yes. That's the point: 0x00 is only ever used to encode codepoint 0. It never shows up anywhere else. That's precisely what the text you replied to means.

dbaupp 13y ago
But using 0 to terminate strings means you can never have a string that actually contains codepoint 0, as the terminator isn't part of the contents of the string.
- f2f 13y ago
  that's a problem for those using 0 to terminate a string. if you don't there's no issue. you can read DMR's historical perspective on choosing 0 as a string terminator here: http://cm.bell-labs.com/who/dmr/chist.html http://cm.bell-labs.com/who/dmr/chist.html (critique section) even the C guys have moved on though, as Go (co-designed by Ken Thompson) illustrates.
- derleth 13y ago
  > But using 0 to terminate strings means you can never have a string that actually contains codepoint 0, as the terminator isn't part of the contents of the string. This is indeed a tradeoff. The only alternatives are to either store the length of the string explicitly somewhere (the Pascal solution is to prepend the string with a fixed-size length parameter, which can be as awkward as it sounds when you get to really long strings) or to do something nasty with the string's actual contents, such as saying that the last byte of a string has its high bit set. I think the C solution is the most reasonable when storage is really tight, and more flexible than the Pascal method in general, but I agree that it's potentially dangerous and it's annoying to have a byte which you can never represent in a string.
  - dbaupp 13y ago
    > more flexible than the Pascal method in general Why? C strings and Pascal strings can store exactly the same contents, except Pascal strings can store a literal \0, and are faster to manipulate (in many ways), at the cost of (sizeof(word) - 1) extra bytes.
    - derleth 13y ago
      Because you can have extremely long strings without worrying about overflowing a fixed-size length prefix.
      - dbaupp 13y ago
        A computer has a finite address space (e.g. 2^32 bytes on x86, 2^48 on x86-64), and always has a fixed size data type large enough to address it all; an in-memory string cannot possibly be usefully larger than this so using this finite-size type as the length-prefix is perfect & optimal. C-strings are useful in extremely constrained environments when the extra few bytes of the length prefix vs the trailing \0 byte is too much to pay, but are essentially just a security risk in any other situation.

by derleth 13y ago

dbaupp 13y ago

But using 0 to terminate strings means you can never have a string that actually contains codepoint 0, as the terminator isn't part of the contents of the string.

f2f 13y ago
that's a problem for those using 0 to terminate a string. if you don't there's no issue. you can read DMR's historical perspective on choosing 0 as a string terminator here: http://cm.bell-labs.com/who/dmr/chist.html http://cm.bell-labs.com/who/dmr/chist.html (critique section) even the C guys have moved on though, as Go (co-designed by Ken Thompson) illustrates.
derleth 13y ago
> But using 0 to terminate strings means you can never have a string that actually contains codepoint 0, as the terminator isn't part of the contents of the string. This is indeed a tradeoff. The only alternatives are to either store the length of the string explicitly somewhere (the Pascal solution is to prepend the string with a fixed-size length parameter, which can be as awkward as it sounds when you get to really long strings) or to do something nasty with the string's actual contents, such as saying that the last byte of a string has its high bit set. I think the C solution is the most reasonable when storage is really tight, and more flexible than the Pascal method in general, but I agree that it's potentially dangerous and it's annoying to have a byte which you can never represent in a string.
- dbaupp 13y ago
  > more flexible than the Pascal method in general Why? C strings and Pascal strings can store exactly the same contents, except Pascal strings can store a literal \0, and are faster to manipulate (in many ways), at the cost of (sizeof(word) - 1) extra bytes.
  - derleth 13y ago
    Because you can have extremely long strings without worrying about overflowing a fixed-size length prefix.
    - dbaupp 13y ago
      A computer has a finite address space (e.g. 2^32 bytes on x86, 2^48 on x86-64), and always has a fixed size data type large enough to address it all; an in-memory string cannot possibly be usefully larger than this so using this finite-size type as the length-prefix is perfect & optimal. C-strings are useful in extremely constrained environments when the extra few bytes of the length prefix vs the trailing \0 byte is too much to pay, but are essentially just a security risk in any other situation.