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  26 <div class="titlepage"><div><div><h4 class="title">
  27 <a name="boost_asio.reference.async_connect.overload1"></a><a class="link" href="overload1.html" title="async_connect (1 of 6 overloads)">async_connect
  28         (1 of 6 overloads)</a>
  29 </h4></div></div></div>
  30 <p>
  31           Asynchronously establishes a socket connection by trying each endpoint
  32           in a sequence.
  33         </p>
  34 <pre class="programlisting">template&lt;
  35     typename <a class="link" href="../Protocol.html" title="Protocol requirements">Protocol</a>,
  36     typename <a class="link" href="../Executor1.html" title="Executor requirements">Executor</a>,
  37     typename <a class="link" href="../EndpointSequence.html" title="Endpoint sequence requirements">EndpointSequence</a>,
  38     typename <a class="link" href="../RangeConnectHandler.html" title="Range connect handler requirements">RangeConnectHandler</a> = <a class="link" href="../asynchronous_operations.html#boost_asio.reference.asynchronous_operations.default_completion_tokens"><span class="emphasis"><em>DEFAULT</em></span></a>&gt;
  39 <a class="link" href="../asynchronous_operations.html#boost_asio.reference.asynchronous_operations.automatic_deduction_of_initiating_function_return_type"><span class="emphasis"><em>DEDUCED</em></span></a> async_connect(
  40     basic_socket&lt; Protocol, Executor &gt; &amp; s,
  41     const EndpointSequence &amp; endpoints,
  42     RangeConnectHandler &amp;&amp; handler = <a class="link" href="../asynchronous_operations.html#boost_asio.reference.asynchronous_operations.default_completion_tokens"><span class="emphasis"><em>DEFAULT</em></span></a>,
  43     typename enable_if&lt; is_endpoint_sequence&lt; EndpointSequence &gt;::value &gt;::type *  = 0);
  44 </pre>
  45 <p>
  46           This function attempts to connect a socket to one of a sequence of endpoints.
  47           It does this by repeated calls to the socket's <code class="computeroutput">async_connect</code>
  48           member function, once for each endpoint in the sequence, until a connection
  49           is successfully established.
  50         </p>
  51 <h6>
  52 <a name="boost_asio.reference.async_connect.overload1.h0"></a>
  53           <span class="phrase"><a name="boost_asio.reference.async_connect.overload1.parameters"></a></span><a class="link" href="overload1.html#boost_asio.reference.async_connect.overload1.parameters">Parameters</a>
  54         </h6>
  55 <div class="variablelist">
  56 <p class="title"><b></b></p>
  57 <dl class="variablelist">
  58 <dt><span class="term">s</span></dt>
  59 <dd><p>
  60                 The socket to be connected. If the socket is already open, it will
  61                 be closed.
  62               </p></dd>
  63 <dt><span class="term">endpoints</span></dt>
  64 <dd><p>
  65                 A sequence of endpoints.
  66               </p></dd>
  67 <dt><span class="term">handler</span></dt>
  68 <dd>
  69 <p>
  70                 The handler to be called when the connect operation completes. Copies
  71                 will be made of the handler as required. The function signature of
  72                 the handler must be:
  73 </p>
  74 <pre class="programlisting">void handler(
  75   // Result of operation. if the sequence is empty, set to
  76   // boost::asio::error::not_found. Otherwise, contains the
  77   // error from the last connection attempt.
  78   const boost::system::error_code&amp; error,
  79
  80   // On success, the successfully connected endpoint.
  81   // Otherwise, a default-constructed endpoint.
  82   const typename Protocol::endpoint&amp; endpoint
  83 );
  84 </pre>
  85 <p>
  86                 Regardless of whether the asynchronous operation completes immediately
  87                 or not, the handler will not be invoked from within this function.
  88                 On immediate completion, invocation of the handler will be performed
  89                 in a manner equivalent to using <a class="link" href="../post.html" title="post"><code class="computeroutput">post</code></a>.
  90               </p>
  91 </dd>
  92 </dl>
  93 </div>
  94 <h6>
  95 <a name="boost_asio.reference.async_connect.overload1.h1"></a>
  96           <span class="phrase"><a name="boost_asio.reference.async_connect.overload1.example"></a></span><a class="link" href="overload1.html#boost_asio.reference.async_connect.overload1.example">Example</a>
  97         </h6>
  98 <pre class="programlisting">tcp::resolver r(my_context);
  99 tcp::resolver::query q("host", "service");
 100 tcp::socket s(my_context);
 101
 102 // ...
 103
 104 r.async_resolve(q, resolve_handler);
 105
 106 // ...
 107
 108 void resolve_handler(
 109     const boost::system::error_code&amp; ec,
 110     tcp::resolver::results_type results)
 111 {
 112   if (!ec)
 113   {
 114     boost::asio::async_connect(s, results, connect_handler);
 115   }
 116 }
 117
 118 // ...
 119
 120 void connect_handler(
 121     const boost::system::error_code&amp; ec,
 122     const tcp::endpoint&amp; endpoint)
 123 {
 124   // ...
 125 }
 126 </pre>
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