Re: std::transform problem

From:
"Victor Bazarov" <v.Abazarov@comAcast.net>
Newsgroups:
comp.lang.c++
Date:
Thu, 10 Apr 2008 09:29:08 -0400
Message-ID:
<ftl4n4$b9v$1@news.datemas.de>
tech wrote:

Hi, I am trying to use the std::transform as follows

where buf is short*

m_SendData is std::vector<unsigned char>

class CCodec
{
public:
CCodec() {};
virtual ~CCodec(){};

virtual unsigned char Encode(short ibuf ) = 0;

virtual short Decode(unsigned char ibuf) = 0;
};

m_Codec is *CCodec but pointing at concrete implementation

std::transform(buf, buf + LEN, std::back_inserter(m_SendData),
m_Codec-

Encode);


Instead of the expression 'm_Codec->Encode' you probably meant to
use a binder:

    'bind1st(mem_fun(&CCodec::Encode), m_Codec)'

(or something like that). The idea is that the last argument to
'transform' needs to be a functor or a function pointer. To make
a functor from an object and a pointer to member, you need to bind
the two together so they can be called like a regular function.

Google "bind1st mem_fun" in the news archives, you'll find more
information.

I get the following errors from VC++ (Visual Studio 8). How to
correct? Thanks

error C3867: CCodec::Encode': function call missing argument list;
use &CCodec::Encode' to create a pointer to member
.: error C2780: '_OutIt
std::transform(_InIt1,_InIt1,_InIt2,_OutIt,_Fn2)' : expects 5
arguments - 4 provided
       C:\Program Files\Microsoft Visual Studio 8\VC\ce\include
\algorithm(797) : see declaration of 'std::transform'


V
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