Add example for C++11 futures.

asio/src/examples/cpp11/Makefile.am

diff --git a/asio/src/examples/cpp11/Makefile.am b/asio/src/examples/cpp11/Makefile.am
index fcb704b..2a0c1b4 100644
--- a/asio/src/examples/cpp11/Makefile.am
+++ b/asio/src/examples/cpp11/Makefile.am
@@ -20,6 +20,7 @@
 	echo/blocking_tcp_echo_server \
 	echo/blocking_udp_echo_client \
 	echo/blocking_udp_echo_server \
+	futures/daytime_client \
 	http/server/http_server
 
 noinst_HEADERS = \
@@ -37,6 +38,7 @@
 echo_blocking_tcp_echo_server_SOURCES = echo/blocking_tcp_echo_server.cpp
 echo_blocking_udp_echo_client_SOURCES = echo/blocking_udp_echo_client.cpp
 echo_blocking_udp_echo_server_SOURCES = echo/blocking_udp_echo_server.cpp
+futures_daytime_client_SOURCES = futures/daytime_client.cpp
 http_server_http_server_SOURCES = \
 	http/server/connection.cpp \
 	http/server/connection_manager.cpp \

asio/src/examples/cpp11/futures/.gitignore

diff --git a/asio/src/examples/cpp11/futures/.gitignore b/asio/src/examples/cpp11/futures/.gitignore
new file mode 100644
index 0000000..0882fa6
--- /dev/null
+++ b/asio/src/examples/cpp11/futures/.gitignore
@@ -0,0 +1,11 @@
+.deps
+.dirstamp
+*.o
+*.obj
+*.exe
+*_server
+*_client
+*.ilk
+*.manifest
+*.pdb
+*.tds

asio/src/examples/cpp11/futures/daytime_client.cpp

diff --git a/asio/src/examples/cpp11/futures/daytime_client.cpp b/asio/src/examples/cpp11/futures/daytime_client.cpp
new file mode 100644
index 0000000..3bcacfb
--- /dev/null
+++ b/asio/src/examples/cpp11/futures/daytime_client.cpp
@@ -0,0 +1,94 @@
+//
+// daytime_client.cpp
+// ~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2012 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <array>
+#include <future>
+#include <iostream>
+#include <thread>
+#include <asio/io_service.hpp>
+#include <asio/ip/udp.hpp>
+#include <asio/use_future.hpp>
+
+using asio::ip::udp;
+
+void get_daytime(asio::io_service& io_service, const char* hostname)
+{
+  try
+  {
+    udp::resolver resolver(io_service);
+
+    std::future<udp::resolver::iterator> iter =
+      resolver.async_resolve(
+          {udp::v4(), hostname, "daytime"},
+          asio::use_future);
+
+    // The async_resolve operation above returns the endpoint iterator as a
+    // future value that is not retrieved ...
+
+    udp::socket socket(io_service, udp::v4());
+
+    std::array<char, 1> send_buf  = {{ 0 }};
+    std::future<std::size_t> send_length =
+      socket.async_send_to(asio::buffer(send_buf),
+          *iter.get(), // ... until here. This call may block.
+          asio::use_future);
+
+    // Do other things here while the send completes.
+
+    send_length.get(); // Blocks until the send is complete. Throws any errors.
+
+    std::array<char, 128> recv_buf;
+    udp::endpoint sender_endpoint;
+    std::future<std::size_t> recv_length =
+      socket.async_receive_from(
+          asio::buffer(recv_buf),
+          sender_endpoint,
+          asio::use_future);
+
+    // Do other things here while the receive completes.
+
+    std::cout.write(
+        recv_buf.data(),
+        recv_length.get()); // Blocks until receive is complete.
+  }
+  catch (std::system_error& e)
+  {
+    std::cerr << e.what() << std::endl;
+  }
+}
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc != 2)
+    {
+      std::cerr << "Usage: daytime_client <host>" << std::endl;
+      return 1;
+    }
+
+    // We run the io_service off in its own thread so that it operates
+    // completely asynchronously with respect to the rest of the program.
+    asio::io_service io_service;
+    asio::io_service::work work(io_service);
+    std::thread thread([&io_service](){ io_service.run(); });
+
+    get_daytime(io_service, argv[1]);
+
+    io_service.stop();
+    thread.join();
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << e.what() << std::endl;
+  }
+
+  return 0;
+}