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<title>async_connect (1 of 6 overloads)</title>
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<div class="titlepage"><div><div><h4 class="title">
<a name="asio.reference.async_connect.overload1"></a><a class="link" href="overload1.html" title="async_connect (1 of 6 overloads)">async_connect
(1 of 6 overloads)</a>
</h4></div></div></div>
<p>
Asynchronously establishes a socket connection by trying each endpoint
in a sequence.
</p>
<pre class="programlisting">template<
typename <a class="link" href="../Protocol.html" title="Protocol requirements">Protocol</a>,
typename <a class="link" href="../Executor1.html" title="Executor requirements">Executor</a>,
typename <a class="link" href="../EndpointSequence.html" title="Endpoint sequence requirements">EndpointSequence</a>,
typename <a class="link" href="../RangeConnectHandler.html" title="Range connect handler requirements">RangeConnectHandler</a> = <a class="link" href="../asynchronous_operations.html#asio.reference.asynchronous_operations.default_completion_tokens"><span class="emphasis"><em>DEFAULT</em></span></a>>
<a class="link" href="../asynchronous_operations.html#asio.reference.asynchronous_operations.automatic_deduction_of_initiating_function_return_type"><span class="emphasis"><em>DEDUCED</em></span></a> async_connect(
basic_socket< Protocol, Executor > & s,
const EndpointSequence & endpoints,
RangeConnectHandler && handler = <a class="link" href="../asynchronous_operations.html#asio.reference.asynchronous_operations.default_completion_tokens"><span class="emphasis"><em>DEFAULT</em></span></a>,
typename enable_if< is_endpoint_sequence< EndpointSequence >::value >::type * = 0);
</pre>
<p>
This function attempts to connect a socket to one of a sequence of endpoints.
It does this by repeated calls to the socket's <code class="computeroutput">async_connect</code>
member function, once for each endpoint in the sequence, until a connection
is successfully established.
</p>
<h6>
<a name="asio.reference.async_connect.overload1.h0"></a>
<span><a name="asio.reference.async_connect.overload1.parameters"></a></span><a class="link" href="overload1.html#asio.reference.async_connect.overload1.parameters">Parameters</a>
</h6>
<div class="variablelist">
<p class="title"><b></b></p>
<dl>
<dt><span class="term">s</span></dt>
<dd><p>
The socket to be connected. If the socket is already open, it will
be closed.
</p></dd>
<dt><span class="term">endpoints</span></dt>
<dd><p>
A sequence of endpoints.
</p></dd>
<dt><span class="term">handler</span></dt>
<dd>
<p>
The handler to be called when the connect operation completes. Copies
will be made of the handler as required. The function signature of
the handler must be:
</p>
<pre class="programlisting">void handler(
// Result of operation. if the sequence is empty, set to
// asio::error::not_found. Otherwise, contains the
// error from the last connection attempt.
const asio::error_code& error,
// On success, the successfully connected endpoint.
// Otherwise, a default-constructed endpoint.
const typename Protocol::endpoint& endpoint
);
</pre>
<p>
Regardless of whether the asynchronous operation completes immediately
or not, the handler will not be invoked from within this function.
On immediate completion, invocation of the handler will be performed
in a manner equivalent to using <a class="link" href="../post.html" title="post"><code class="computeroutput">post</code></a>.
</p>
</dd>
</dl>
</div>
<h6>
<a name="asio.reference.async_connect.overload1.h1"></a>
<span><a name="asio.reference.async_connect.overload1.example"></a></span><a class="link" href="overload1.html#asio.reference.async_connect.overload1.example">Example</a>
</h6>
<pre class="programlisting">tcp::resolver r(my_context);
tcp::resolver::query q("host", "service");
tcp::socket s(my_context);
// ...
r.async_resolve(q, resolve_handler);
// ...
void resolve_handler(
const asio::error_code& ec,
tcp::resolver::results_type results)
{
if (!ec)
{
asio::async_connect(s, results, connect_handler);
}
}
// ...
void connect_handler(
const asio::error_code& ec,
const tcp::endpoint& endpoint)
{
// ...
}
</pre>
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<td align="right"><div class="copyright-footer">Copyright © 2003-2020 Christopher M.
Kohlhoff<p>
Distributed under the Boost Software License, Version 1.0. (See accompanying
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>)
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