使用 Visual Studio Boost asio TCP IP asio 类编译错误。 错误：C2228：“.close”的左边必须有类/结构/联合

Question

I'm trying to follow the steps provided in this page

http://www.boost.org/doc/libs/1_46_0/doc/html/boost_asio/tutorial/tutdaytime1.html

However, at some point the code does not compile, and gives me the specified error. I can't understand what kind of conflict it is. The object tcpsock doesn't seem to be correctly created. Please check my code:

io_service io_tcp;
tcp::resolver resolverObject(io_tcp);
tcp::resolver::query queryObject(argv[1], "daytime");
tcp::resolver::iterator endpoint_iterator = resolverObject.resolve(queryObject);
tcp::resolver::iterator end; //default constructor is end iterator

tcp::socket tcpsock(io_service);
boost::system::error_code socketError = boost::asio::error::host_not_found;

while (socketError && endpoint_iterator != end)
{
    //Apparently, the object isn't created correctly
    tcpsock.close(); //error happenes here
    tcpsock.connect(*endpoint_iterator++, socketError); //error happenes here too
}
if (socketError)
    throw boost::system::system_error(socketError);

Thank you for any efforts.

Answer 1

要初始化tcpsock与类型io_service ，而不是与变量io_tcp 。

Answer 2

I also found this compile error but from a different angle given the following:

    boost::asio::read(socket, replyBuf, boost::asio::transfer_all(), error);

Compared to the correct:

boost::asio::read(*socket, replyBuf, boost::asio::transfer_all(), error);

Notice the need the de-reference the socket. It seems boost's use of common base types prevents the usual intellisense errors.

In the future I recommend adding a null check before use for the args of a boost type at runtime.