in reply to Re^50: Interleaving bytes in a string quickly
in thread Interleaving bytes in a string quickly

(You still haven't demonstrated how you can get those four to exist with only two string types)

You know that +1 and the assigned \0 in your code, don't allocate +1 and don't put \0 and there you go.

The \0 is not required, but much XS assume it's there.

Read as: If sv contains the character string "\x80\x81",

I don't understand. How is calling a byte string a character string useful? Why would you do that? It's not technically wrong, but it's definitely not clearer.

I realize that C calls both bytes and characters char, but I don't think that's something to aspire to.

  • Comment on Re^51: Interleaving bytes in a string quickly

Replies are listed 'Best First'.
Re^52: Interleaving bytes in a string quickly
by BrowserUk (Patriarch) on Mar 03, 2010 at 10:12 UTC

    Aaaaaaaaaaaaaaarg! Where is your head at?

    I don't understand. How is calling a byte string a character string useful?

    It's not "calling a byte string a character string". It's calling a string containing multi-byte characters, a character string.

    Because the only way SvPVX() can return a pointer to more than 2 bytes of ram at the C-level, is if the SV contains a scalar containing 2 (multi-byte) characters at the Perl level.

    If the scalar contains a string containing just two bytes, then SvPVX() will return a pointer to just exactly 2 bytes. It can do nothing else, as we've at length established, because SvPVX() performs no coercions.

    (You still haven't demonstrated how you can get those four to exist with only two string types)

    You know that +1 and the assigned \0 in your code, don't allocate +1 and don't put \0 and there you go.

    Now you're either just taking the piss, or you're talking gibberish.

    Because there is no +1 in my code, and the only assignment of \0 is into the output buffer. Which has nothing whatsoever to do with the input accessed via SvPVX().

    The "those four to exist" to which I refer, are the four possibilities that you claimed SvPVX() could return a pointer to, variously, either 2, 3, 4 or 5 bytes of ram.

    Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
    "Science is about questioning the status quo. Questioning authority".
    In the absence of evidence, opinion is indistinguishable from prejudice.
[reply]

      It's calling a string containing multi-byte characters, a character string.

      No, you used it to denote both multi and single byte character formats.

      Because there is no +1 in my code, and the only assignment of \0 is into the output buffer

      You asked how to construct a var without a \0. I used an example from your own code, the construction of the output buffer. The +1 is done for you by SvPV.

[reply]
        No. He didn't.
[reply]

In Section Seekers of Perl Wisdom