1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>async_connect (3 of 6 overloads)</title> 5<link rel="stylesheet" href="../../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../../../boost_asio.html" title="Boost.Asio"> 8<link rel="up" href="../async_connect.html" title="async_connect"> 9<link rel="prev" href="overload2.html" title="async_connect (2 of 6 overloads)"> 10<link rel="next" href="overload4.html" title="async_connect (4 of 6 overloads)"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr> 14<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../boost.png"></td> 15<td align="center"><a href="../../../../../index.html">Home</a></td> 16<td align="center"><a href="../../../../../libs/libraries.htm">Libraries</a></td> 17<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 18<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 19<td align="center"><a href="../../../../../more/index.htm">More</a></td> 20</tr></table> 21<hr> 22<div class="spirit-nav"> 23<a accesskey="p" href="overload2.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../async_connect.html"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../boost_asio.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="overload4.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h4 class="title"> 27<a name="boost_asio.reference.async_connect.overload3"></a><a class="link" href="overload3.html" title="async_connect (3 of 6 overloads)">async_connect 28 (3 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< 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 Iterator, 38 typename <a class="link" href="../IteratorConnectHandler.html" title="Iterator connect handler requirements">IteratorConnectHandler</a> = <a class="link" href="../asynchronous_operations.html#boost_asio.reference.asynchronous_operations.default_completion_tokens"><span class="emphasis"><em>DEFAULT</em></span></a>> 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< Protocol, Executor > & s, 41 Iterator begin, 42 Iterator end, 43 IteratorConnectHandler && handler = <a class="link" href="../asynchronous_operations.html#boost_asio.reference.asynchronous_operations.default_completion_tokens"><span class="emphasis"><em>DEFAULT</em></span></a>); 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.overload3.h0"></a> 53 <span class="phrase"><a name="boost_asio.reference.async_connect.overload3.parameters"></a></span><a class="link" href="overload3.html#boost_asio.reference.async_connect.overload3.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">begin</span></dt> 64<dd><p> 65 An iterator pointing to the start of a sequence of endpoints. 66 </p></dd> 67<dt><span class="term">end</span></dt> 68<dd><p> 69 An iterator pointing to the end of a sequence of endpoints. 70 </p></dd> 71<dt><span class="term">handler</span></dt> 72<dd> 73<p> 74 The handler to be called when the connect operation completes. Copies 75 will be made of the handler as required. The function signature of 76 the handler must be: 77</p> 78<pre class="programlisting">void handler( 79 // Result of operation. if the sequence is empty, set to 80 // boost::asio::error::not_found. Otherwise, contains the 81 // error from the last connection attempt. 82 const boost::system::error_code& error, 83 84 // On success, an iterator denoting the successfully 85 // connected endpoint. Otherwise, the end iterator. 86 Iterator iterator 87); 88</pre> 89<p> 90 Regardless of whether the asynchronous operation completes immediately 91 or not, the handler will not be invoked from within this function. 92 On immediate completion, invocation of the handler will be performed 93 in a manner equivalent to using <a class="link" href="../post.html" title="post"><code class="computeroutput">post</code></a>. 94 </p> 95</dd> 96</dl> 97</div> 98<h6> 99<a name="boost_asio.reference.async_connect.overload3.h1"></a> 100 <span class="phrase"><a name="boost_asio.reference.async_connect.overload3.example"></a></span><a class="link" href="overload3.html#boost_asio.reference.async_connect.overload3.example">Example</a> 101 </h6> 102<pre class="programlisting">std::vector<tcp::endpoint> endpoints = ...; 103tcp::socket s(my_context); 104boost::asio::async_connect(s, 105 endpoints.begin(), endpoints.end(), 106 connect_handler); 107 108// ... 109 110void connect_handler( 111 const boost::system::error_code& ec, 112 std::vector<tcp::endpoint>::iterator i) 113{ 114 // ... 115} 116</pre> 117</div> 118<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 119<td align="left"></td> 120<td align="right"><div class="copyright-footer">Copyright © 2003-2020 Christopher M. 121 Kohlhoff<p> 122 Distributed under the Boost Software License, Version 1.0. (See accompanying 123 file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) 124 </p> 125</div></td> 126</tr></table> 127<hr> 128<div class="spirit-nav"> 129<a accesskey="p" href="overload2.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../async_connect.html"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../boost_asio.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="overload4.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> 130</div> 131</body> 132</html> 133
