behaviour of bytevector

[Anthony Liu]

I have similar problems when I tried to write the vorbis cover art and
reported it about one month ago.

2010/4/22 Lukáš Lalinský <lalinsky at gmail.com>

> On Wed, Apr 21, 2010 at 9:01 PM, Matthieu Riolo
> <matthieu.riolo at googlemail.com> wrote:
> > Hello everybody
> > I've just an small question but the problem is it really confusing me. I
> > wrote an obj-c wrapper around the taglib class and I tried to integrate
> the
> > Ogg Vorbis METADATA_BLOCK_PICTURE into the wrapper. I tried to work
> > ByteVector but it seems that it does not behaviour like I thought. But
> maybe
> > I just did not understand what the idea is behind ByteVector. For me it
> was
> > clear that the class just manipulates the memory in a comfortable way.
> > However, I seem to be unabled to put the complete data into memory!
> >
> > NSLog(@"%u",
> > TagLib::String(TagLib::ByteVector(TagLib::ByteVector::fromUInt(10,
> > true))).size());
> > The code above will return 1! I recognized this problem as I tried to set
> 4
> > bytes long integervalues with the quantity of 0. It occurs that the
> > ByteVector contains the correct datasize but no data. This way ByteVector
> is
> > always empty and will not append any data to his content (even if he
> resize
> > correct).
> >
> > So me question is: Did I missed something? Or did I just run over a
> strange
> > obj-c vs c++ case? For me it's important to know if this "strip" effect
> is
> > wished or not. Because in me case it is absolutly in the way.
>
> The problem is conversion of a byte vector with NULL bytes to a string.
>
> I'm not sure if this is a copy&paste error in your example, but the
> code should return 0. ByteVector::fromUInt(10, true) creates a byte
> vector with four bytes 0x00 0x00 0x00 0x0A. The second
> ByteVector(byteVector) creates a copy, so it's useless in this case.
> String(ByteVector("\x00\x00\x00\x0A", 4)) tries to convert the bytes
> into a string using Latin-1. It sees \x00 as the first character, so
> it stops parsing it. The result is an empty string.
>
> Btw, if you use ByteVector::fromUInt(10, false), the byte order would
> be reversed and you would get a string with one character (ASCII code
> \x0A).
>
> Lukas
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>



-- 
Best Regards
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