c++ - 解析函数在 boost/asio 中不起作用

Question

我正在学习 boost/asio 并编写电子书中的示例程序。当然没用 ;)

#include <boost/asio.hpp>
#include <iostream>

int main () {
   boost::asio::io_service io_service;
   boost::asio::ip::tcp::resolver::query query("www.boost.org", "http");
   boost::asio::ip::tcp::resolver::iterator destination = boost::asio::ip::tcp::resolver::resolve(query); // if i have "." before "resolve" as in books example compilers says i need primary-expresion. 
   boost::asio::ip::tcp::endpoint endpoint;

   while ( destination != end ) {
      endpoint = *destination++;
      std::cout<<endpoint<<std::endl;
   }

   boost::asio::ip::tcp::socket socket(io_service);
   socket.connect(endpoint);
   return 0;
}

在“resolve”之前带有“::”的编译器输出:

/home/martins/C++/boost_asio_client/client.cpp|7|error: cannot call member function 
‘boost::asio::ip::basic_resolver<InternetProtocol, ResolverService>::iterator 
boost::asio::ip::basic_resolver<InternetProtocol, 
ResolverService>::resolve(boost::asio::ip::basic_resolver<InternetProtocol,
 ResolverService>::query&) 
[with InternetProtocol = boost::asio::ip::tcp, ResolverService = 
boost::asio::ip::resolver_service<boost::asio::ip::tcp>, 
boost::asio::ip::basic_resolver<InternetProtocol, ResolverService>::iterator = 
boost::asio::ip::basic_resolver_iterator<boost::asio::ip::tcp>, 
boost::asio::ip::basic_resolver<InternetProtocol, ResolverService>::query = 
boost::asio::ip::basic_resolver_query<boost::asio::ip::tcp>]’ without object|

如何正确解析地址？

Answer 1

您需要一个解析器 对象。此外，您的迭代器比较不正确，您需要与标记值 ip::tcp::resolver::iterator() 进行比较。

#include <boost/asio.hpp>
#include <iostream>

int main () {
   boost::asio::io_service io_service;
   boost::asio::ip::tcp::resolver::query query("www.boost.org", "http");
   boost::asio::ip::tcp::resolver resolver( io_service );
   boost::asio::ip::tcp::resolver::iterator destination = resolver.resolve(query);
   boost::asio::ip::tcp::endpoint endpoint;

   while ( destination != boost::asio::ip::tcp::resolver::iterator() ) {
     endpoint = *destination++;
     std::cout<<endpoint<<std::endl;
   }

   boost::asio::ip::tcp::socket socket(io_service);
   socket.connect(endpoint);
   return 0;
}

这里是您的代码的示例编译和运行。

samm@macmini ~> g++ -lboost_system resolve.cc
samm@macmini ~> ./a.out 
129.79.245.252:80
samm@macmini ~> echo $?
0
samm@macmini ~>