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<?xml version="1.0" encoding="iso-8859-1"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "DTD/xhtml1-strict.dtd">
<html><head><title>QHostInfo Class Reference</title><style>h3.fn,span.fn { margin-left: 1cm; text-indent: -1cm }
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</style></head><body><table border="0" cellpadding="0" cellspacing="0" width="100%"><tr /><td align="left" valign="top" width="32"><img align="left" border="0" height="32" src="images/rb-logo.png" width="32" /></td><td width="1">  </td><td class="postheader" valign="center"><a href="index.html"><font color="#004faf">Home</font></a> · <a href="classes.html"><font color="#004faf">All Classes</font></a> · <a href="modules.html"><font color="#004faf">Modules</font></a></td></table><h1 align="center">QHostInfo Class Reference<br /><sup><sup>[<a href="qtnetwork.html">QtNetwork</a> module]</sup></sup></h1><p>The QHostInfo class provides static functions for host name
lookups. <a href="#details">More...</a></p>
<h3>Types</h3><ul><li><div class="fn" />enum <b><a href="qhostinfo.html#HostInfoError-enum">HostInfoError</a></b> { NoError, HostNotFound, UnknownError }</li></ul><h3>Methods</h3><ul><li><div class="fn" /><b><a href="qhostinfo.html#QHostInfo">__init__</a></b> (<i>self</i>, int <i>id</i> = -1)</li><li><div class="fn" /><b><a href="qhostinfo.html#QHostInfo-2">__init__</a></b> (<i>self</i>, QHostInfo <i>d</i>)</li><li><div class="fn" />unknown-type <b><a href="qhostinfo.html#addresses">addresses</a></b> (<i>self</i>)</li><li><div class="fn" />HostInfoError <b><a href="qhostinfo.html#error">error</a></b> (<i>self</i>)</li><li><div class="fn" />QString <b><a href="qhostinfo.html#errorString">errorString</a></b> (<i>self</i>)</li><li><div class="fn" />QString <b><a href="qhostinfo.html#hostName">hostName</a></b> (<i>self</i>)</li><li><div class="fn" />int <b><a href="qhostinfo.html#lookupId">lookupId</a></b> (<i>self</i>)</li><li><div class="fn" /><b><a href="qhostinfo.html#setAddresses">setAddresses</a></b> (<i>self</i>, unknown-type <i>addresses</i>)</li><li><div class="fn" /><b><a href="qhostinfo.html#setError">setError</a></b> (<i>self</i>, HostInfoError <i>error</i>)</li><li><div class="fn" /><b><a href="qhostinfo.html#setErrorString">setErrorString</a></b> (<i>self</i>, QString <i>errorString</i>)</li><li><div class="fn" /><b><a href="qhostinfo.html#setHostName">setHostName</a></b> (<i>self</i>, QString <i>name</i>)</li><li><div class="fn" /><b><a href="qhostinfo.html#setLookupId">setLookupId</a></b> (<i>self</i>, int <i>id</i>)</li></ul><h3>Static Methods</h3><ul><li><div class="fn" /><b><a href="qhostinfo.html#abortHostLookup">abortHostLookup</a></b> (int <i>lookupId</i>)</li><li><div class="fn" />QHostInfo <b><a href="qhostinfo.html#fromName">fromName</a></b> (QString <i>name</i>)</li><li><div class="fn" />QString <b><a href="qhostinfo.html#localDomainName">localDomainName</a></b> ()</li><li><div class="fn" />QString <b><a href="qhostinfo.html#localHostName">localHostName</a></b> ()</li><li><div class="fn" />int <b><a href="qhostinfo.html#lookupHost">lookupHost</a></b> (QString <i>name</i>, QObject <i>receiver</i>, object <i>member</i>)</li><li><div class="fn" />int <b><a href="qhostinfo.html#lookupHost-2">lookupHost</a></b> (QString <i>name</i>, object <i>slot</i>)</li></ul><a name="details" /><hr /><h2>Detailed Description</h2><p>The QHostInfo class provides static functions for host name
lookups.</p>
<p>QHostInfo uses the lookup mechanisms provided by the operating
system to find the IP address(es) associated with a host name, or
the host name associated with an IP address. The class provides two
static convenience functions: one that works asynchronously and
emits a signal once the host is found, and one that blocks and
returns a QHostInfo object.</p>
<p>To look up a host's IP addresses asynchronously, call <a href="qhostinfo.html#lookupHost">lookupHost</a>(), which takes the host
name or IP address, a receiver object, and a slot signature as
arguments and returns an ID. You can abort the lookup by calling
<a href="qhostinfo.html#abortHostLookup">abortHostLookup</a>() with
the lookup ID.</p>
<p>Example:</p>
<pre class="cpp">
<span class="comment">// To find the IP address of qt.nokia.com</span>
<span class="type">QHostInfo</span><span class="operator">.</span><a href="qhostinfo.html#lookupHost">lookupHost</a>(<span class="string">"qt.nokia.com"</span><span class="operator">,</span>
<span class="keyword">this</span><span class="operator">,</span> SLOT(printResults(<span class="type">QHostInfo</span>)));
<span class="comment">// To find the host name for 4.2.2.1</span>
<span class="type">QHostInfo</span><span class="operator">.</span><a href="qhostinfo.html#lookupHost">lookupHost</a>(<span class="string">"4.2.2.1"</span><span class="operator">,</span>
<span class="keyword">this</span><span class="operator">,</span> SLOT(printResults(<span class="type">QHostInfo</span>)));
</pre>
<p>The slot is invoked when the results are ready. The results are
stored in a QHostInfo object. Call <a href="qhostinfo.html#addresses">addresses</a>() to get the list of IP
addresses for the host, and <a href="qhostinfo.html#hostName">hostName</a>() to get the host name that
was looked up.</p>
<p>If the lookup failed, <a href="qhostinfo.html#error">error</a>()
returns the type of error that occurred. <a href="qhostinfo.html#errorString">errorString</a>() gives a
human-readable description of the lookup error.</p>
<p>If you want a blocking lookup, use the <a href="qhostinfo.html#fromName">QHostInfo.fromName</a>() function:</p>
<pre class="cpp">
<span class="type">QHostInfo</span> info <span class="operator">=</span> <span class="type">QHostInfo</span><span class="operator">.</span><a href="qhostinfo.html#fromName">fromName</a>(<span class="string">"qt.nokia.com"</span>);
</pre>
<p>QHostInfo supports Internationalized Domain Names (IDNs) through
the IDNA and Punycode standards.</p>
<p>To retrieve the name of the local host, use the static <a href="qhostinfo.html#localHostName">QHostInfo.localHostName</a>()
function.</p>
<p><b>Note:</b> Since Qt 4.6.1 QHostInfo is using multiple threads
for DNS lookup instead of one dedicated DNS thread. This improves
performance, but also changes the order of signal emissions when
using <a href="qhostinfo.html#lookupHost">lookupHost</a>() compared
to previous versions of Qt. <b>Note:</b> Since Qt 4.6.3 QHostInfo
is using a small internal 60 second DNS cache for performance
improvements.</p>
<hr /><h2>Type Documentation</h2><h3 class="fn"><a name="HostInfoError-enum" />QHostInfo.HostInfoError</h3><p>This enum describes the various errors that can occur when
trying to resolve a host name.</p>
<table class="valuelist">
<tr class="odd" valign="top">
<th class="tblConst">Constant</th>
<th class="tblval">Value</th>
<th class="tbldscr">Description</th>
</tr>
<tr>
<td class="topAlign"><tt>QHostInfo.NoError</tt></td>
<td class="topAlign"><tt>0</tt></td>
<td class="topAlign">The lookup was successful.</td>
</tr>
<tr>
<td class="topAlign"><tt>QHostInfo.HostNotFound</tt></td>
<td class="topAlign"><tt>1</tt></td>
<td class="topAlign">No IP addresses were found for the host.</td>
</tr>
<tr>
<td class="topAlign"><tt>QHostInfo.UnknownError</tt></td>
<td class="topAlign"><tt>2</tt></td>
<td class="topAlign">An unknown error occurred.</td>
</tr>
</table>
<p><b>See also</b> <a href="qhostinfo.html#error">error</a>() and
<a href="qhostinfo.html#setError">setError</a>().</p>
<hr /><h2>Method Documentation</h2><h3 class="fn"><a name="QHostInfo" />QHostInfo.__init__ (<i>self</i>, int <i>id</i> = -1)</h3><p>Constructs an empty host info object with lookup ID
<i>id</i>.</p>
<p><b>See also</b> <a href="qhostinfo.html#lookupId">lookupId</a>().</p>
<h3 class="fn"><a name="QHostInfo-2" />QHostInfo.__init__ (<i>self</i>, <a href="qhostinfo.html">QHostInfo</a> <i>d</i>)</h3><p>Constructs a copy of <i>other</i>.</p>
<h3 class="fn"><a name="abortHostLookup" />QHostInfo.abortHostLookup (int <i>lookupId</i>)</h3><p>Aborts the host lookup with the ID <i>id</i>, as returned by
<a href="qhostinfo.html#lookupHost">lookupHost</a>().</p>
<p><b>See also</b> <a href="qhostinfo.html#lookupHost">lookupHost</a>() and <a href="qhostinfo.html#lookupId">lookupId</a>().</p>
<h3 class="fn"><a name="addresses" />unknown-type QHostInfo.addresses (<i>self</i>)</h3><p>Returns the list of IP addresses associated with <a href="qhostinfo.html#hostName">hostName</a>(). This list may be
empty.</p>
<p>Example:</p>
<pre class="cpp">
<span class="type"><a href="qhostinfo.html">QHostInfo</a></span> info;
<span class="operator">.</span><span class="operator">.</span><span class="operator">.</span>
<span class="keyword">if</span> (<span class="operator">!</span>info<span class="operator">.</span>addresses()<span class="operator">.</span>isEmpty()) {
<span class="type"><a href="qhostaddress.html">QHostAddress</a></span> address <span class="operator">=</span> info<span class="operator">.</span>addresses()<span class="operator">.</span>first();
<span class="comment">// use the first IP address</span>
}
</pre>
<p><b>See also</b> <a href="qhostinfo.html#setAddresses">setAddresses</a>(), <a href="qhostinfo.html#hostName">hostName</a>(), and <a href="qhostinfo.html#error">error</a>().</p>
<h3 class="fn"><a name="error" /><a href="qhostinfo.html#HostInfoError-enum">HostInfoError</a> QHostInfo.error (<i>self</i>)</h3><p>Returns the type of error that occurred if the host name lookup
failed; otherwise returns <a href="qhostinfo.html#HostInfoError-enum">NoError</a>.</p>
<p><b>See also</b> <a href="qhostinfo.html#setError">setError</a>()
and <a href="qhostinfo.html#errorString">errorString</a>().</p>
<h3 class="fn"><a name="errorString" />QString QHostInfo.errorString (<i>self</i>)</h3><p>If the lookup failed, this function returns a human readable
description of the error; otherwise "Unknown error" is
returned.</p>
<p><b>See also</b> <a href="qhostinfo.html#setErrorString">setErrorString</a>() and <a href="qhostinfo.html#error">error</a>().</p>
<h3 class="fn"><a name="fromName" /><a href="qhostinfo.html">QHostInfo</a> QHostInfo.fromName (QString <i>name</i>)</h3><p>Looks up the IP address(es) for the given host <i>name</i>. The
function blocks during the lookup which means that execution of the
program is suspended until the results of the lookup are ready.
Returns the result of the lookup in a <a href="qhostinfo.html">QHostInfo</a> object.</p>
<p>If you pass a literal IP address to <i>name</i> instead of a
host name, <a href="qhostinfo.html">QHostInfo</a> will search for
the domain name for the IP (i.e., <a href="qhostinfo.html">QHostInfo</a> will perform a <i>reverse</i>
lookup). On success, the returned <a href="qhostinfo.html">QHostInfo</a> will contain both the resolved
domain name and IP addresses for the host name.</p>
<p><b>See also</b> <a href="qhostinfo.html#lookupHost">lookupHost</a>().</p>
<h3 class="fn"><a name="hostName" />QString QHostInfo.hostName (<i>self</i>)</h3><p>Returns the name of the host whose IP addresses were looked
up.</p>
<p><b>See also</b> <a href="qhostinfo.html#setHostName">setHostName</a>() and <a href="qhostinfo.html#localHostName">localHostName</a>().</p>
<h3 class="fn"><a name="localDomainName" />QString QHostInfo.localDomainName ()</h3><p>Returns the DNS domain of this machine.</p>
<p>Note: DNS domains are not related to domain names found in
Windows networks.</p>
<p><b>See also</b> <a href="qhostinfo.html#hostName">hostName</a>().</p>
<h3 class="fn"><a name="localHostName" />QString QHostInfo.localHostName ()</h3><p>Returns the host name of this machine.</p>
<p><b>See also</b> <a href="qhostinfo.html#hostName">hostName</a>().</p>
<h3 class="fn"><a name="lookupHost" />int QHostInfo.lookupHost (QString <i>name</i>, <a href="qobject.html">QObject</a> <i>receiver</i>, object <i>member</i>)</h3><p>Looks up the IP address(es) associated with host name
<i>name</i>, and returns an ID for the lookup. When the result of
the lookup is ready, the slot or signal <i>member</i> in
<i>receiver</i> is called with a <a href="qhostinfo.html">QHostInfo</a> argument. The <a href="qhostinfo.html">QHostInfo</a> object can then be inspected to get
the results of the lookup.</p>
<p>The lookup is performed by a single function call, for
example:</p>
<pre class="cpp">
<span class="type"><a href="qhostinfo.html">QHostInfo</a></span><span class="operator">.</span>lookupHost(<span class="string">"www.kde.org"</span><span class="operator">,</span>
<span class="keyword">this</span><span class="operator">,</span> SLOT(lookedUp(<span class="type"><a href="qhostinfo.html">QHostInfo</a></span>)));
</pre>
<p>The implementation of the slot prints basic information about
the addresses returned by the lookup, or reports an error if it
failed:</p>
<pre class="cpp">
<span class="type">void</span> MyWidget<span class="operator">.</span>lookedUp(<span class="keyword">const</span> <span class="type"><a href="qhostinfo.html">QHostInfo</a></span> <span class="operator">&</span>host)
{
<span class="keyword">if</span> (host<span class="operator">.</span>error() <span class="operator">!</span><span class="operator">=</span> <span class="type"><a href="qhostinfo.html">QHostInfo</a></span><span class="operator">.</span>NoError) {
<a href="qtcore.html#qDebug">qDebug</a>() <span class="operator"><</span><span class="operator"><</span> <span class="string">"Lookup failed:"</span> <span class="operator"><</span><span class="operator"><</span> host<span class="operator">.</span>errorString();
<span class="keyword">return</span>;
}
foreach (<span class="keyword">const</span> <span class="type"><a href="qhostaddress.html">QHostAddress</a></span> <span class="operator">&</span>address<span class="operator">,</span> host<span class="operator">.</span>addresses())
<a href="qtcore.html#qDebug">qDebug</a>() <span class="operator"><</span><span class="operator"><</span> <span class="string">"Found address:"</span> <span class="operator"><</span><span class="operator"><</span> address<span class="operator">.</span>toString();
}
</pre>
<p>If you pass a literal IP address to <i>name</i> instead of a
host name, <a href="qhostinfo.html">QHostInfo</a> will search for
the domain name for the IP (i.e., <a href="qhostinfo.html">QHostInfo</a> will perform a <i>reverse</i>
lookup). On success, the resulting <a href="qhostinfo.html">QHostInfo</a> will contain both the resolved
domain name and IP addresses for the host name. Example:</p>
<pre class="cpp">
<span class="type"><a href="qhostinfo.html">QHostInfo</a></span><span class="operator">.</span>lookupHost(<span class="string">"4.2.2.1"</span><span class="operator">,</span>
<span class="keyword">this</span><span class="operator">,</span> SLOT(lookedUp(<span class="type"><a href="qhostinfo.html">QHostInfo</a></span>)));
</pre>
<p><b>Note:</b> There is no guarantee on the order the signals will
be emitted if you start multiple requests with lookupHost().</p>
<p><b>See also</b> <a href="qhostinfo.html#abortHostLookup">abortHostLookup</a>(), <a href="qhostinfo.html#addresses">addresses</a>(), <a href="qhostinfo.html#error">error</a>(), and <a href="qhostinfo.html#fromName">fromName</a>().</p>
<h3 class="fn"><a name="lookupHost-2" />int QHostInfo.lookupHost (QString <i>name</i>, object <i>slot</i>)</h3><h3 class="fn"><a name="lookupId" />int QHostInfo.lookupId (<i>self</i>)</h3><p>Returns the ID of this lookup.</p>
<p><b>See also</b> <a href="qhostinfo.html#setLookupId">setLookupId</a>(), <a href="qhostinfo.html#abortHostLookup">abortHostLookup</a>(), and
<a href="qhostinfo.html#hostName">hostName</a>().</p>
<h3 class="fn"><a name="setAddresses" />QHostInfo.setAddresses (<i>self</i>, unknown-type <i>addresses</i>)</h3><p>Sets the list of addresses in this <a href="qhostinfo.html">QHostInfo</a> to <i>addresses</i>.</p>
<p><b>See also</b> <a href="qhostinfo.html#addresses">addresses</a>().</p>
<h3 class="fn"><a name="setError" />QHostInfo.setError (<i>self</i>, <a href="qhostinfo.html#HostInfoError-enum">HostInfoError</a> <i>error</i>)</h3><p>Sets the error type of this <a href="qhostinfo.html">QHostInfo</a> to <i>error</i>.</p>
<p><b>See also</b> <a href="qhostinfo.html#error">error</a>() and
<a href="qhostinfo.html#errorString">errorString</a>().</p>
<h3 class="fn"><a name="setErrorString" />QHostInfo.setErrorString (<i>self</i>, QString <i>errorString</i>)</h3><p>Sets the human readable description of the error that occurred
to <i>str</i> if the lookup failed.</p>
<p><b>See also</b> <a href="qhostinfo.html#errorString">errorString</a>() and <a href="qhostinfo.html#setError">setError</a>().</p>
<h3 class="fn"><a name="setHostName" />QHostInfo.setHostName (<i>self</i>, QString <i>name</i>)</h3><p>Sets the host name of this <a href="qhostinfo.html">QHostInfo</a> to <i>hostName</i>.</p>
<p><b>See also</b> <a href="qhostinfo.html#hostName">hostName</a>().</p>
<h3 class="fn"><a name="setLookupId" />QHostInfo.setLookupId (<i>self</i>, int <i>id</i>)</h3><p>Sets the ID of this lookup to <i>id</i>.</p>
<p><b>See also</b> <a href="qhostinfo.html#lookupId">lookupId</a>()
and <a href="qhostinfo.html#lookupHost">lookupHost</a>().</p>
<address><hr /><div align="center"><table border="0" cellspacing="0" width="100%"><tr class="address"><td align="left" width="25%">PyQt 4.12.1 for X11</td><td align="center" width="50%">Copyright © <a href="http://www.riverbankcomputing.com">Riverbank Computing Ltd</a> and <a href="http://www.qt.io">The Qt Company</a> 2015</td><td align="right" width="25%">Qt 4.8.7</td></tr></table></div></address></body></html>
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