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<html><!-- #BeginTemplate "/Templates/tmpl.dwt" --><!-- DW6 --><head><!-- #BeginEditable "doctitle" --> <title>PTypes: streams: error handling</title><!-- #EndEditable --> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><link rel="stylesheet" href="styles.css"></head><body bgcolor="#FFFFFF" leftmargin="40" marginwidth="40"><p><a href="../index.html"><img src="title-20.png" width="253" height="39" alt="C++ Portable Types Library (PTypes) Version 2.0" border="0"></a> <hr size="1" noshade><!-- #BeginEditable "body" --> <p class="hpath"><a href="index.html">Top</a>: <a href="streams.html">Streams</a>: Error handling</p><p>When a recoverable error occurs during input/output operations, an exception of type <span class="lang">(estream*)</span> is being thrown. The exception object contains an error message which can be shown to the user. The message is accessible through <span class="def">estream::get_message()</span>. </p><p>The example below shows how to catch an exception and recover normal execution of the program:</p><blockquote> <pre>#include <pstreams.h>USING_PTYPESinfile f("somefile.txt");try { f.open(); while(!f.get_eof()) <span class="comment"> // read the file...</span>}catch (estream* e) { perr.putline(e->get_message()); delete e;}</pre></blockquote><p>The <span class="lang">estream</span> class provides a system error code in UNIX errno semantics through <span class="def">estream::get_code()</span>. On Windows most error codes are translated into corresponding UNIX errno codes. Less frequently occurring errors are translated to a generic errno code EIO. When an <span class="lang">estream</span> object returns EIO, the actual message string is constructed based on the status code of the stream. For example, if the status code was IO_OPENING, the error code was EIO, the message would be "Couldn't open <i>[filename]</i>". For explanations on what each errno code means, see comments in <span class="lang">src/piobase.cxx</span> source file.</p><p><span class="lang">Estream</span> also provides a reference to the stream object that raised the error condition through <span class="lang">estream::get_errstm()</span>.</p><p class="seealso">See also: <a href="streams.iobase.html">iobase</a>, <a href="streams.examples.html">Examples</a></p><!-- #EndEditable --><hr size="1"><a href="../index.html" class="ns">PTypes home</a></body><!-- #EndTemplate --></html>⌨️ 快捷键说明
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