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  26 <div class="titlepage"><div><div><h5 class="title">
  27 <a name="boost_asio.reference.ip__basic_resolver.async_resolve.overload5"></a><a class="link" href="overload5.html" title="ip::basic_resolver::async_resolve (5 of 6 overloads)">ip::basic_resolver::async_resolve
  28           (5 of 6 overloads)</a>
  29 </h5></div></div></div>
  30 <p>
  31             Asynchronously perform forward resolution of a query to a list of entries.
  32           </p>
  33 <pre class="programlisting">template&lt;
  34     typename <a class="link" href="../../ResolveHandler.html" title="Resolve handler requirements">ResolveHandler</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;
  35 <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_resolve(
  36     const protocol_type &amp; protocol,
  37     string_view host,
  38     string_view service,
  39     resolver_base::flags resolve_flags,
  40     ResolveHandler &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>);
  41 </pre>
  42 <p>
  43             This function is used to resolve host and service names into a list of
  44             endpoint entries.
  45           </p>
  46 <h6>
  47 <a name="boost_asio.reference.ip__basic_resolver.async_resolve.overload5.h0"></a>
  48             <span class="phrase"><a name="boost_asio.reference.ip__basic_resolver.async_resolve.overload5.parameters"></a></span><a class="link" href="overload5.html#boost_asio.reference.ip__basic_resolver.async_resolve.overload5.parameters">Parameters</a>
  49           </h6>
  50 <div class="variablelist">
  51 <p class="title"><b></b></p>
  52 <dl class="variablelist">
  53 <dt><span class="term">protocol</span></dt>
  54 <dd><p>
  55                   A protocol object, normally representing either the IPv4 or IPv6
  56                   version of an internet protocol.
  57                 </p></dd>
  58 <dt><span class="term">host</span></dt>
  59 <dd><p>
  60                   A string identifying a location. May be a descriptive name or a
  61                   numeric address string. If an empty string and the passive flag
  62                   has been specified, the resolved endpoints are suitable for local
  63                   service binding. If an empty string and passive is not specified,
  64                   the resolved endpoints will use the loopback address.
  65                 </p></dd>
  66 <dt><span class="term">service</span></dt>
  67 <dd><p>
  68                   A string identifying the requested service. This may be a descriptive
  69                   name or a numeric string corresponding to a port number. May be
  70                   an empty string, in which case all resolved endpoints will have
  71                   a port number of 0.
  72                 </p></dd>
  73 <dt><span class="term">resolve_flags</span></dt>
  74 <dd><p>
  75                   A set of flags that determine how name resolution should be performed.
  76                   The default flags are suitable for communication with remote hosts.
  77                   See the <a class="link" href="../../ip__resolver_base.html" title="ip::resolver_base"><code class="computeroutput">ip::resolver_base</code></a>
  78                   documentation for the set of available flags.
  79                 </p></dd>
  80 <dt><span class="term">handler</span></dt>
  81 <dd>
  82 <p>
  83                   The handler to be called when the resolve operation completes.
  84                   Copies will be made of the handler as required. The function signature
  85                   of the handler must be:
  86 </p>
  87 <pre class="programlisting">void handler(
  88   const boost::system::error_code&amp; error, // Result of operation.
  89   resolver::results_type results // Resolved endpoints as a range.
  90 );
  91 </pre>
  92 <p>
  93                   Regardless of whether the asynchronous operation completes immediately
  94                   or not, the handler will not be invoked from within this function.
  95                   On immediate completion, invocation of the handler will be performed
  96                   in a manner equivalent to using <a class="link" href="../../post.html" title="post"><code class="computeroutput">post</code></a>.
  97                 </p>
  98 </dd>
  99 </dl>
 100 </div>
 101 <p>
 102             A successful resolve operation is guaranteed to pass a non-empty range
 103             to the handler.
 104           </p>
 105 <h6>
 106 <a name="boost_asio.reference.ip__basic_resolver.async_resolve.overload5.h1"></a>
 107             <span class="phrase"><a name="boost_asio.reference.ip__basic_resolver.async_resolve.overload5.remarks"></a></span><a class="link" href="overload5.html#boost_asio.reference.ip__basic_resolver.async_resolve.overload5.remarks">Remarks</a>
 108           </h6>
 109 <p>
 110             On POSIX systems, host names may be locally defined in the file <code class="computeroutput">/etc/hosts</code>.
 111             On Windows, host names may be defined in the file <code class="computeroutput">c:\windows\system32\drivers\etc\hosts</code>.
 112             Remote host name resolution is performed using DNS. Operating systems
 113             may use additional locations when resolving host names (such as NETBIOS
 114             names on Windows).
 115           </p>
 116 <p>
 117             On POSIX systems, service names are typically defined in the file <code class="computeroutput">/etc/services</code>.
 118             On Windows, service names may be found in the file <code class="computeroutput">c:\windows\system32\drivers\etc\services</code>.
 119             Operating systems may use additional locations when resolving service
 120             names.
 121           </p>
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