mingw/html/lib/Errno.html

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  13 <big><strong><span class="block">&nbsp;Errno - System errno constants</span></strong></big>
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  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="#caveats">CAVEATS</a></li>
  26         <li><a href="#author">AUTHOR</a></li>
  27         <li><a href="#copyright">COPYRIGHT</a></li>
  28 </ul>
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  30
  31 <hr />
  32 <p>
  33 </p>
  34 <h1><a name="name">NAME</a></h1>
  35 <p>Errno - System errno constants</p>
  36 <p>
  37 </p>
  38 <hr />
  39 <h1><a name="synopsis">SYNOPSIS</a></h1>
  40 <pre>
  41     use Errno qw(EINTR EIO :POSIX);</pre>
  42 <p>
  43 </p>
  44 <hr />
  45 <h1><a name="description">DESCRIPTION</a></h1>
  46 <p><code>Errno</code> defines and conditionally exports all the error constants
  47 defined in your system <code>errno.h</code> include file. It has a single export
  48 tag, <code>:POSIX</code>, which will export all POSIX defined error numbers.</p>
  49 <p><code>Errno</code> also makes <a href="file://C|\msysgit\mingw\html/pod/perlvar.html#item___"><code>%!</code></a> magic such that each element of <a href="file://C|\msysgit\mingw\html/pod/perlvar.html#item___"><code>%!</code></a> has a
  50 non-zero value only if <a href="file://C|\msysgit\mingw\html/pod/perlvar.html#item___"><code>$!</code></a> is set to that value. For example:</p>
  51 <pre>
  52     use Errno;</pre>
  53 <pre>
  54     unless (open(FH, &quot;/fangorn/spouse&quot;)) {
  55         if ($!{ENOENT}) {
  56             warn &quot;Get a wife!\n&quot;;
  57         } else {
  58             warn &quot;This path is barred: $!&quot;;
  59         }
  60     }</pre>
  61 <p>If a specified constant <code>EFOO</code> does not exist on the system, <code>$!{EFOO}</code>
  62 returns <code>&quot;&quot;</code>.  You may use <code>exists $!{EFOO}</code> to check whether the
  63 constant is available on the system.</p>
  64 <p>
  65 </p>
  66 <hr />
  67 <h1><a name="caveats">CAVEATS</a></h1>
  68 <p>Importing a particular constant may not be very portable, because the
  69 import will fail on platforms that do not have that constant.  A more
  70 portable way to set <a href="file://C|\msysgit\mingw\html/pod/perlvar.html#item___"><code>$!</code></a> to a valid value is to use:</p>
  71 <pre>
  72     if (exists &amp;Errno::EFOO) {
  73         $! = &amp;Errno::EFOO;
  74     }</pre>
  75 <p>
  76 </p>
  77 <hr />
  78 <h1><a name="author">AUTHOR</a></h1>
  79 <p>Graham Barr &lt;<a href="mailto:gbarr@pobox.com">gbarr@pobox.com</a>&gt;</p>
  80 <p>
  81 </p>
  82 <hr />
  83 <h1><a name="copyright">COPYRIGHT</a></h1>
  84 <p>Copyright (c) 1997-8 Graham Barr. All rights reserved.
  85 This program is free software; you can redistribute it and/or modify it
  86 under the same terms as Perl itself.</p>
  87 <table border="0" width="100%" cellspacing="0" cellpadding="3">
  88 <tr><td class="block" style="background-color: #cccccc" valign="middle">
  89 <big><strong><span class="block">&nbsp;Errno - System errno constants</span></strong></big>
  90 </td></tr>
  91 </table>
  92
  93 </body>
  94
  95 </html>