Re: [Boost-users] usage of boost::asio::async_write and boost::asio::buffer

Subject: Re: [Boost-users] usage of boost::asio::async_write and boost::asio::buffer
From: Ozgur Ozturk (ozgur7_at_[hidden])
Date: 2009-07-21 16:07:21

>if you wish to send the whole string, you don't have to
>pass a size...but the string must be
>alive until the completion handler is called.

OK, now I try that. I use a member variable string instead of char*. I got
another error.
I tried to use the same string as buffer for both async_read_some and
async_write
I guess the string can not be treated as a mutable buffer, so maybe I should
keep the original char * buffer for async_read_some and use the string only
for outputting with async_write. Is that right?
(or any other recommendation?)

//NOW data_ member variable is string istead of char*
  void start()
  {
    socket_.async_read_some(boost::asio::buffer(data_),
        boost::bind(&session::handle_login, this,
          boost::asio::placeholders::error,
          boost::asio::placeholders::bytes_transferred));
  }

Error message includes:
c:\program
files\boost\boost_1_38\boost\asio\detail\win_iocp_socket_service.hpp(1409) :
error C2664: 'boost::asio::mutable_buffer::mutable_buffer(const
boost::asio::mutable_buffer &)' : cannot convert parameter 1 from 'const
boost::asio::const_buffer' to 'const boost::asio::mutable_buffer &'
        Reason: cannot convert from 'const boost::asio::const_buffer' to
'const boost::asio::mutable_buffer'
        No user-defined-conversion operator available that can perform this
conversion, or the operator cannot be called

You can see the full error messages I get here:
http://pastebin.com/f4ee951e4

TIA
Best regards,
Ozgur (Oscar) Ozturk
www.DrOzturk.com
Phone: +1 (908) DROZGUR
i.e,        [phone]

On Tue, Jul 21, 2009 at 7:14 AM, Igor R <boost.lists_at_[hidden]> wrote:

> > boost::asio::async_write(socket_,
> >               boost::asio::buffer(replyString, replyString.size()),
> >               boost::bind(&session::handle_write, this,
> >                 boost::asio::placeholders::error));
> >
> > I generate the replyString to have results from my database query
> separated
> > with ^ signs (which is used to tokenize the replyString on the client
> > side...)
> >
> >             string replyString="1^";
>
> boost::asio::buffer does not copy your local string, so the string
> vanishes before the actual async. write takes place.
> By the way, if you wish to send the whole string, you don't have to
> pass a size: boost::asio::buffer(replyString) - but the string must be
> alive until the completion handler is called.
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