mingw/html/lib/Net/hostent.html

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   5 <title>Net::hostent - by-name interface to Perl's built-in gethost* functions</title>
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  13 <big><strong><span class="block">&nbsp;Net::hostent - by-name interface to Perl's built-in gethost* functions</span></strong></big>
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  16
  17 <p><a name="__index__"></a></p>
  18 <!-- INDEX BEGIN -->
  19
  20 <ul>
  21
  22         <li><a href="#name">NAME</a></li>
  23         <li><a href="#synopsis">SYNOPSIS</a></li>
  24         <li><a href="#description">DESCRIPTION</a></li>
  25         <li><a href="#examples">EXAMPLES</a></li>
  26         <li><a href="#note">NOTE</a></li>
  27         <li><a href="#author">AUTHOR</a></li>
  28 </ul>
  29 <!-- INDEX END -->
  30
  31 <hr />
  32 <p>
  33 </p>
  34 <h1><a name="name">NAME</a></h1>
  35 <p>Net::hostent - by-name interface to Perl's built-in gethost*() functions</p>
  36 <p>
  37 </p>
  38 <hr />
  39 <h1><a name="synopsis">SYNOPSIS</a></h1>
  40 <pre>
  41  use Net::hostent;</pre>
  42 <p>
  43 </p>
  44 <hr />
  45 <h1><a name="description">DESCRIPTION</a></h1>
  46 <p>This module's default exports override the core <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_gethostbyname"><code>gethostbyname()</code></a> and
  47 <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_gethostbyaddr"><code>gethostbyaddr()</code></a> functions, replacing them with versions that return
  48 ``Net::hostent'' objects.  This object has methods that return the similarly
  49 named structure field name from the C's hostent structure from <em>netdb.h</em>;
  50 namely name, aliases, addrtype, length, and addr_list.  The aliases and
  51 addr_list methods return array reference, the rest scalars.  The addr
  52 method is equivalent to the zeroth element in the addr_list array
  53 reference.</p>
  54 <p>You may also import all the structure fields directly into your namespace
  55 as regular variables using the :FIELDS import tag.  (Note that this still
  56 overrides your core functions.)  Access these fields as variables named
  57 with a preceding <code>h_</code>.  Thus, <code>$host_obj-&gt;name()</code> corresponds to
  58 $h_name if you import the fields.  Array references are available as
  59 regular array variables, so for example <code>@{ $host_obj-&gt;aliases()
  60 }</code> would be simply @h_aliases.</p>
  61 <p>The <code>gethost()</code> function is a simple front-end that forwards a numeric
  62 argument to <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_gethostbyaddr"><code>gethostbyaddr()</code></a> by way of Socket::inet_aton, and the rest
  63 to gethostbyname().</p>
  64 <p>To access this functionality without the core overrides,
  65 pass the <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_use"><code>use</code></a> an empty import list, and then access
  66 function functions with their full qualified names.
  67 On the other hand, the built-ins are still available
  68 via the <code>CORE::</code> pseudo-package.</p>
  69 <p>
  70 </p>
  71 <hr />
  72 <h1><a name="examples">EXAMPLES</a></h1>
  73 <pre>
  74  use Net::hostent;
  75  use Socket;</pre>
  76 <pre>
  77  @ARGV = ('netscape.com') unless @ARGV;</pre>
  78 <pre>
  79  for $host ( @ARGV ) {</pre>
  80 <pre>
  81     unless ($h = gethost($host)) {
  82         warn &quot;$0: no such host: $host\n&quot;;
  83         next;
  84     }</pre>
  85 <pre>
  86     printf &quot;\n%s is %s%s\n&quot;,
  87             $host,
  88             lc($h-&gt;name) eq lc($host) ? &quot;&quot; : &quot;*really* &quot;,
  89             $h-&gt;name;</pre>
  90 <pre>
  91     print &quot;\taliases are &quot;, join(&quot;, &quot;, @{$h-&gt;aliases}), &quot;\n&quot;
  92                 if @{$h-&gt;aliases};</pre>
  93 <pre>
  94     if ( @{$h-&gt;addr_list} &gt; 1 ) {
  95         my $i;
  96         for $addr ( @{$h-&gt;addr_list} ) {
  97             printf &quot;\taddr #%d is [%s]\n&quot;, $i++, inet_ntoa($addr);
  98         }
  99     } else {
 100         printf &quot;\taddress is [%s]\n&quot;, inet_ntoa($h-&gt;addr);
 101     }</pre>
 102 <pre>
 103     if ($h = gethostbyaddr($h-&gt;addr)) {
 104         if (lc($h-&gt;name) ne lc($host)) {
 105             printf &quot;\tThat addr reverses to host %s!\n&quot;, $h-&gt;name;
 106             $host = $h-&gt;name;
 107             redo;
 108         }
 109     }
 110  }</pre>
 111 <p>
 112 </p>
 113 <hr />
 114 <h1><a name="note">NOTE</a></h1>
 115 <p>While this class is currently implemented using the Class::Struct
 116 module to build a struct-like class, you shouldn't rely upon this.</p>
 117 <p>
 118 </p>
 119 <hr />
 120 <h1><a name="author">AUTHOR</a></h1>
 121 <p>Tom Christiansen</p>
 122 <table border="0" width="100%" cellspacing="0" cellpadding="3">
 123 <tr><td class="block" style="background-color: #cccccc" valign="middle">
 124 <big><strong><span class="block">&nbsp;Net::hostent - by-name interface to Perl's built-in gethost* functions</span></strong></big>
 125 </td></tr>
 126 </table>
 127
 128 </body>
 129
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