Pulling data from website

[rjphares]

I am trying to get stock data from a website. Is there a way to do this with boost?

[JLBorges]

Boost.Beast (HTTP/1 protocol layering over Boost.Asio, requires C++11 and boost libraries) https://www.boost.org/doc/libs/1_77_0/libs/beast/doc/html/index.html

Example: https://www.boost.org/doc/libs/1_77_0/libs/beast/doc/html/index.html

[kbw]

Once you understand how to use the HTTP Client, you'll need to make a REST GET request to fetch the data.
https://restfulapi.net/http-methods/#get

[rjphares]

I'm using VS 2019 and used nuget package manager to install boost v1.77. This is the example I'm using

#include <boost/beast/core.hpp>
#include <boost/beast/http.hpp>
#include <boost/beast/version.hpp>
#include <boost/asio/connect.hpp>
#include <boost/asio/ip/tcp.hpp>
#include <cstdlib>
#include <iostream>
#include <string>

namespace beast = boost::beast;     // from <boost/beast.hpp>
namespace http = beast::http;       // from <boost/beast/http.hpp>
namespace net = boost::asio;        // from <boost/asio.hpp>
using tcp = net::ip::tcp;           // from <boost/asio/ip/tcp.hpp>

// Performs an HTTP GET and prints the response
int main(int argc, char** argv)
{
  try
  {
    // Check command line arguments.
    if (argc != 4 && argc != 5)
    {
      std::cerr <<
        "Usage: http-client-sync <host> <port> <target> [<HTTP version: 1.0 or 1.1(default)>]\n" <<
        "Example:\n" <<
        "    http-client-sync www.example.com 80 /\n" <<
        "    http-client-sync www.example.com 80 / 1.0\n";
      return EXIT_FAILURE;
    }
    auto const host = argv[1];
    auto const port = argv[2];
    auto const target = argv[3];
    int version = argc == 5 && !std::strcmp("1.0", argv[4]) ? 10 : 11;

    // The io_context is required for all I/O
    net::io_context ioc;

    // These objects perform our I/O
    tcp::resolver resolver(ioc);
    beast::tcp_stream stream(ioc);

    // Look up the domain name
    auto const results = resolver.resolve(host, port);

    // Make the connection on the IP address we get from a lookup
    stream.connect(results);

    // Set up an HTTP GET request message
    http::request<http::string_body> req{ http::verb::get, target, version };
    req.set(http::field::host, host);
    req.set(http::field::user_agent, BOOST_BEAST_VERSION_STRING);

    // Send the HTTP request to the remote host
    http::write(stream, req);

    // This buffer is used for reading and must be persisted
    beast::flat_buffer buffer;

    // Declare a container to hold the response
    http::response<http::dynamic_body> res;

    // Receive the HTTP response
    http::read(stream, buffer, res);

    // Write the message to standard out
    std::cout << res << std::endl;

    // Gracefully close the socket
    beast::error_code ec;
    stream.socket().shutdown(tcp::socket::shutdown_both, ec);

    // not_connected happens sometimes
    // so don't bother reporting it.
    //
    if (ec && ec != beast::errc::not_connected)
      throw beast::system_error{ ec };

    // If we get here then the connection is closed gracefully
  }
  catch (std::exception const& e)
  {
    std::cerr << "Error: " << e.what() << std::endl;
    return EXIT_FAILURE;
  }
  return EXIT_SUCCESS;
}

This is the output from VS 2019:

'Project8.exe' (Win32): Loaded 'C:\Users\rjpha\source\repos\Project8\Debug\Project8.exe'. Symbols loaded.
'Project8.exe' (Win32): Loaded 'C:\Windows\SysWOW64\ntdll.dll'. 
'Project8.exe' (Win32): Loaded 'C:\Windows\SysWOW64\kernel32.dll'. 
'Project8.exe' (Win32): Loaded 'C:\Windows\SysWOW64\KernelBase.dll'. 
'Project8.exe' (Win32): Loaded 'C:\Windows\SysWOW64\ws2_32.dll'. 
'Project8.exe' (Win32): Loaded 'C:\Windows\SysWOW64\rpcrt4.dll'. 
'Project8.exe' (Win32): Loaded 'C:\Windows\SysWOW64\msvcp140d.dll'. 
'Project8.exe' (Win32): Loaded 'C:\Windows\SysWOW64\vcruntime140d.dll'. 
'Project8.exe' (Win32): Loaded 'C:\Windows\SysWOW64\ucrtbased.dll'. 
The thread 0x2270 has exited with code 0 (0x0).
'Project8.exe' (Win32): Loaded 'C:\Windows\SysWOW64\kernel.appcore.dll'. 
'Project8.exe' (Win32): Loaded 'C:\Windows\SysWOW64\msvcrt.dll'. 
'Project8.exe' (Win32): Loaded 'C:\Windows\SysWOW64\NapiNSP.dll'. 
'Project8.exe' (Win32): Loaded 'C:\Windows\SysWOW64\ucrtbase.dll'. 
'Project8.exe' (Win32): Loaded 'C:\Windows\SysWOW64\sechost.dll'. 
'Project8.exe' (Win32): Loaded 'C:\Windows\SysWOW64\pnrpnsp.dll'. 
'Project8.exe' (Win32): Loaded 'C:\Windows\SysWOW64\mswsock.dll'. 
'Project8.exe' (Win32): Loaded 'C:\Windows\SysWOW64\dnsapi.dll'. 
'Project8.exe' (Win32): Loaded 'C:\Windows\SysWOW64\IPHLPAPI.DLL'. 
'Project8.exe' (Win32): Loaded 'C:\Windows\SysWOW64\nsi.dll'. 
'Project8.exe' (Win32): Loaded 'C:\Windows\SysWOW64\winrnr.dll'. 
'Project8.exe' (Win32): Loaded 'C:\Windows\SysWOW64\wshbth.dll'. 
'Project8.exe' (Win32): Loaded 'C:\Windows\SysWOW64\nlansp_c.dll'. 
'Project8.exe' (Win32): Loaded 'C:\Windows\SysWOW64\msvcp_win.dll'. 
onecore\net\netprofiles\service\src\nsp\dll\namespaceserviceprovider.cpp(550)\nlansp_c.dll!738385D4: (caller: 76CECD00) LogHr(1) tid(3614) 8007277C No such service is known. The service cannot be found in the specified name space.
'Project8.exe' (Win32): Loaded 'C:\Windows\SysWOW64\rasadhlp.dll'. 
Exception thrown at 0x7609E7B2 in Project8.exe: Microsoft C++ exception: boost::wrapexcept<boost::system::system_error> at memory location 0x00B3EF68.
The thread 0x6128 has exited with code 0 (0x0).
'Project8.exe' (Win32): Unloaded 'C:\Windows\SysWOW64\sechost.dll'
'Project8.exe' (Win32): Unloaded 'C:\Windows\SysWOW64\NapiNSP.dll'
'Project8.exe' (Win32): Unloaded 'C:\Windows\SysWOW64\pnrpnsp.dll'
'Project8.exe' (Win32): Unloaded 'C:\Windows\SysWOW64\mswsock.dll'
'Project8.exe' (Win32): Unloaded 'C:\Windows\SysWOW64\nsi.dll'
'Project8.exe' (Win32): Unloaded 'C:\Windows\SysWOW64\IPHLPAPI.DLL'
'Project8.exe' (Win32): Unloaded 'C:\Windows\SysWOW64\dnsapi.dll'
'Project8.exe' (Win32): Unloaded 'C:\Windows\SysWOW64\winrnr.dll'
'Project8.exe' (Win32): Unloaded 'C:\Windows\SysWOW64\wshbth.dll'
'Project8.exe' (Win32): Unloaded 'C:\Windows\SysWOW64\msvcp_win.dll'
'Project8.exe' (Win32): Unloaded 'C:\Windows\SysWOW64\ucrtbase.dll'
'Project8.exe' (Win32): Unloaded 'C:\Windows\SysWOW64\nlansp_c.dll'
The thread 0x40a0 has exited with code 1 (0x1).
The thread 0x16f0 has exited with code 1 (0x1).
The thread 0x464 has exited with code 1 (0x1).
The program '[18568] Project8.exe' has exited with code 1 (0x1).

[kbw]

Maybe it's that resolver code? Dunno, I don't have easy access to Windows.

Have you tried stepping thru your code in the debugger?