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<title>PTypes: networking: utilities</title>
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<p><a href="../index.html"><img src="title-21.png" width="253" height="39" alt="C++ Portable Types Library (PTypes) Version 2.1" border="0"></a>
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<p class="hpath"><a href="index.html">Top</a>: <a href="inet.html">Networking</a>:
Utilities</p>
<blockquote>
<pre class="lang">#include <pinet.h>
string iptostring(ipaddress ip);
ipaddress phostbyname(const string& name);
string phostbyaddr(ipaddress ip);
string phostcname(const string& name);
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<p>Many PTypes networking utility functions and class methods manipulate a new
data type <span class="lang">ipaddress</span> - IPv4 (4-byte) internetwork address
type. The objects of this type can be constructed either by explicitly specifying
the 4 bytes separately (e.g. <span class="lang">ipaddress(192, 168, 1, 1)</span>)
or by assigning another <span class="lang">ipaddress</span>. The objects of this
type are mutually compatible with <span class="lang">unsigned long</span> type,
however, you can not rely on the order of bytes if an <span class="lang">ipaddress</span>
is converted to a <span class="lang">unsigned long</span> and vice versa. This
implicit typecast is provided only for comparing an <span class="lang">ipaddress</span>
value with 0 or <span class="lang">ipnone</span> (see <a href="inet.examples.html">Examples</a>).</p>
<p><span class="def">string iptostring(ipaddress ip)</span> converts an IP address
to a string, e.g. <span class="lang">ipaddress(127, 0, 0, 1)</span> would be "127.0.0.1".</p>
<p><span class="def">ipaddress phostbyname(const string& name)</span> resolves
a symbolic DNS name or a numeric IP addresses to <span class="lang">ipaddress</span>.
On error this function returns <span class="lang">ipnone</span>.</p>
<p><span class="def">string phostbyaddr(ipaddress ip)</span> performs reverse
DNS lookup for the given IP address. On error this function returns an empty string.</p>
<p><span class="def">string phostcname(const string& name)</span> returns
the canonical name of the host. On error this function returns an empty string.</p>
<p class="seealso">See also: <a href="inet.ipstream.html">ipstream</a>, <a href="inet.ipstmserver.html">ipstmserver</a>,
<a href="inet.examples.html">Examples</a></p>
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