如何在asio :: buffer()中使用std :: string [英] How to use std::string with asio::buffer()

问题描述

当我尝试将std :: string与boost :: asio :: buffer:一起使用时，出现以下错误消息

I get the following error message when I'm trying to use std::string with boost::asio::buffer:

boost/asio/detail/consuming_buffers.hpp:
In constructor
'boost::asio::detail::consuming_buffers<
        boost::asio::mutable_buffer, boost::asio::const_buffers_1
    >::consuming_buffers(const boost::asio::const_buffers_1 &)':
boost/asio/impl/read.hpp:140:25:  
instantiated from
'boost::asio::detail::read_op<
        boost::asio::basic_stream_socket<boost::asio::ip::tcp>,
boost::asio::const_buffers_1
      , boost::asio::detail::transfer_all_t
      , boost::_bi::bind_t<
            void, boost::_mfi::mf1<void, read_op, const
boost::system::error_code &>
          , boost::_bi::list2<boost::_bi::value<read_op
*>, boost::arg<1> (*)()> 
        > 
    >::read_op(
        boost::asio::basic_stream_socket<boost::asio::ip::tcp>
&, const boost::asio::const_buffers_1
&
      , boost::asio::detail::transfer_all_t
      , boost::_bi::bind_t<
            void, boost::_mfi::mf1<void, read_op, const
boost::system::error_code &>
          , boost::_bi::list2<boost::_bi::value<read_op
*>, boost::arg<1> (*)()>
        >
    )'

[...]

完整源代码: http://liveworkspace.org/code/eca749f6f2714b7c3c4df9f26a404d86

推荐答案

我认为问题是您正在将const缓冲区传递给async_read而不是可变缓冲区.在第50行结尾的块中，boost::asio::buffer(_header)返回const缓冲区.您应该执行boost::asio::async_read(s, boost::asio::buffer(data, size), handler)之类的操作，因为boost::asio::buffer(data, size)会创建一个可变缓冲区.

I think the problem is that you are passing a const buffer to async_read instead of a mutable buffer. In the block ending in line 50, boost::asio::buffer(_header) returns a const buffer. You should do something like boost::asio::async_read(s, boost::asio::buffer(data, size), handler), because boost::asio::buffer(data, size) creates a mutable buffer.

您可能需要使用char数组，而不是对_header和_data使用std::string，例如:

Instead of using std::strings for _header and _data, you probably need to use arrays of char, such as:

char* _data;
boost::asio::buffer(_data, strlen(_data));

请参阅buffer和async_read的参考文档.

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