Re: Simplest way to download a web page and print the content to
stdout with boost
gervaz <ger...@gmail.com> wrote:
On Jun 13, 1:42 pm, "Francesco S. Carta" <entul...@gmail.com> wrote:
gervaz <ger...@gmail.com> wrote:
Hi all,
can you provide me the easiest way to download a web page (e.g.http:/=
/www.nytimes.com) and print the output to stdout using the boost
library?
Thanks,
Mattia
Yes, we can :-)
Sorry, but you should try to find the way by yourself first - that's
not hard, split the problem and ask Google, find pointers and follow
them, try to write some code and compile it. If you don't succeed you
can post here your attempts and someone will eventually point out the
mistakes.
--
FSChttp://userscripts.org/scripts/show/59948
Ok, nice advice :P
Here what I've done (adapted from what I've found reading the doc and
googling):
#include <iostream>
#include <boost/asio.hpp>
int main()
{
boost::asio::io_service io_service ;
boost::asio::ip::tcp::resolver resolver(io_service) ;
boost::asio::ip::tcp::resolver::query query("www.nytimes.com",
"http");
boost::asio::ip::tcp::resolver::iterator iter =
resolver.resolve(query);
boost::asio::ip::tcp::resolver::iterator end;
boost::asio::ip::tcp::endpoint endpoint;
while (iter != end)
{
endpoint = *iter++;
std::cout << endpoint << std::endl;
}
boost::asio::ip::tcp::socket socket(io_service);
socket.connect(endpoint);
boost::asio::streambuf request;
std::ostream request_stream(&request);
request_stream << "GET / HTTP/1.0\r\n";
request_stream << "Host: localhost \r\n";
request_stream << "Accept: */*\r\n";
request_stream << "Connection: close\r\n\r\n";
boost::asio::write(socket, request);
boost::asio::streambuf response;
boost::asio::read_until(socket, response, "\r\n\r\n");
std::cout << &response << std::endl;
return 0;
}
But I'm not able to retrieve the entire web content.
Other questions:
- the while loop seems like an iterator loop, but what
boost::asio::ip::tcp::resolver::iterator end stands for? Is a zero
value?
Whatever the value, in the framework of STL iterators the "end" one is
simply something used to match the end of the container / stream /
whatever so that you know there isn't more data / objects to get. You
shouldn't worry about its actual value - I ignore the details too,
maybe there is something wrong with your program and I'll have a look,
but I'm pressed and I wanted to drop in my 2 cents.
- to see the output I had to use &response, why?
That's not good to pass the address of a container to an ostream
unless you're sure its actual representation matches that of a null-
terminated c-style string. In this case I suppose you have to convert
that buffer to something else, in order to print its data.
There is also the chance that you have to
- call "read_until" to fill the buffer
- pick out the data from the buffer (eventually flushing / emptying
it)
multiple times, until there is no more data to fill it.
Hope that helps you refining your shot.
--
FSC
http://userscripts.org/scripts/show/59948