Question

我正在学习boost / asio并编写电子书中的示例程序。当然它不起作用;）

#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”之前使用“::”编译输出：

/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|

任何人都可以告诉我如何正确解析地址？

Answer 1

你需要一个resolver对象。您的迭代器比较也不正确，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;
}

这是编译和运行代码的示例。

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

Answer 2

resolve不是静态成员函数，所以你需要创建一个解析器对象，然后在该对象上调用成员函数，比如（从内存中去，所以不要抱我这个在任何接近完美的地方）：

int main () {
   boost::asio::io_service io_service; // existing
   boost::asio::ip::tcp::resolver::query query("www.boost.org", "http"); // existing

   boost::asio::ip::tcp::resolver resolver(io_service);  // added

   // modified to use object defined above:
   boost::asio::ip::tcp::resolver::iterator destination = resolver.resolve(query);

解析函数在boost / asio中不起作用

2 个答案: