Migrate remaining c++03 examples to c++11.

example/cpp11/tutorial/timer4/timer.cpp

@@ -0,0 +1,54 @@
+//
+// timer.cpp
+// ~~~~~~~~~
+//
+// Copyright (c) 2003-2023 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 <functional>
+#include <iostream>
+#include <boost/asio.hpp>
+
+class printer
+{
+public:
+  printer(boost::asio::io_context& io)
+    : timer_(io, boost::asio::chrono::seconds(1)),
+      count_(0)
+  {
+    timer_.async_wait(std::bind(&printer::print, this));
+  }
+
+  ~printer()
+  {
+    std::cout << "Final count is " << count_ << std::endl;
+  }
+
+  void print()
+  {
+    if (count_ < 5)
+    {
+      std::cout << count_ << std::endl;
+      ++count_;
+
+      timer_.expires_at(timer_.expiry() + boost::asio::chrono::seconds(1));
+      timer_.async_wait(std::bind(&printer::print, this));
+    }
+  }
+
+private:
+  boost::asio::steady_timer timer_;
+  int count_;
+};
+
+int main()
+{
+  boost::asio::io_context io;
+  printer p(io);
+  io.run();
+
+  return 0;
+}