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<div class="section" id="file-objects">
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<span id="fileobjects"></span><h1>File Objects<a class="headerlink" href="#file-objects" title="Permalink to this headline">¶</a></h1>
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<p id="index-0">These APIs are a minimal emulation of the Python 2 C API for built-in file
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objects, which used to rely on the buffered I/O (<code class="xref c c-type docutils literal notranslate"><span class="pre">FILE*</span></code>) support
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from the C standard library. In Python 3, files and streams use the new
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<a class="reference internal" href="../library/io.html#module-io" title="io: Core tools for working with streams."><code class="xref py py-mod docutils literal notranslate"><span class="pre">io</span></code></a> module, which defines several layers over the low-level unbuffered
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I/O of the operating system. The functions described below are
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convenience C wrappers over these new APIs, and meant mostly for internal
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error reporting in the interpreter; third-party code is advised to access
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the <a class="reference internal" href="../library/io.html#module-io" title="io: Core tools for working with streams."><code class="xref py py-mod docutils literal notranslate"><span class="pre">io</span></code></a> APIs instead.</p>
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<dl class="function">
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<dt id="c.PyFile_FromFd">
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<code class="descname">PyFile_FromFd</code><span class="sig-paren">(</span>int<em> fd</em>, const char<em> *name</em>, const char<em> *mode</em>, int<em> buffering</em>, const char<em> *encoding</em>, const char<em> *errors</em>, const char<em> *newline</em>, int<em> closefd</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyFile_FromFd" title="Permalink to this definition">¶</a></dt>
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<dd><em class="refcount">Return value: New reference.</em><p>Create a Python file object from the file descriptor of an already
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opened file <em>fd</em>. The arguments <em>name</em>, <em>encoding</em>, <em>errors</em> and <em>newline</em>
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can be <em>NULL</em> to use the defaults; <em>buffering</em> can be <em>-1</em> to use the
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default. <em>name</em> is ignored and kept for backward compatibility. Return
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<em>NULL</em> on failure. For a more comprehensive description of the arguments,
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please refer to the <a class="reference internal" href="../library/io.html#io.open" title="io.open"><code class="xref py py-func docutils literal notranslate"><span class="pre">io.open()</span></code></a> function documentation.</p>
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<div class="admonition warning">
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<p class="admonition-title">Warning</p>
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<p>Since Python streams have their own buffering layer, mixing them with
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OS-level file descriptors can produce various issues (such as unexpected
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ordering of data).</p>
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</div>
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<div class="versionchanged">
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<p><span class="versionmodified changed">Changed in version 3.2: </span>Ignore <em>name</em> attribute.</p>
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</div>
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</dd></dl>
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<dl class="function">
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<dt id="c.PyObject_AsFileDescriptor">
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int <code class="descname">PyObject_AsFileDescriptor</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *p</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyObject_AsFileDescriptor" title="Permalink to this definition">¶</a></dt>
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<dd><p>Return the file descriptor associated with <em>p</em> as an <code class="xref c c-type docutils literal notranslate"><span class="pre">int</span></code>. If the
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object is an integer, its value is returned. If not, the
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object’s <a class="reference internal" href="../library/io.html#io.IOBase.fileno" title="io.IOBase.fileno"><code class="xref py py-meth docutils literal notranslate"><span class="pre">fileno()</span></code></a> method is called if it exists; the
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method must return an integer, which is returned as the file descriptor
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value. Sets an exception and returns <code class="docutils literal notranslate"><span class="pre">-1</span></code> on failure.</p>
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</dd></dl>
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<dl class="function">
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<dt id="c.PyFile_GetLine">
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<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a>* <code class="descname">PyFile_GetLine</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *p</em>, int<em> n</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyFile_GetLine" title="Permalink to this definition">¶</a></dt>
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<dd><em class="refcount">Return value: New reference.</em><p id="index-1">Equivalent to <code class="docutils literal notranslate"><span class="pre">p.readline([n])</span></code>, this function reads one line from the
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object <em>p</em>. <em>p</em> may be a file object or any object with a
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<a class="reference internal" href="../library/io.html#io.IOBase.readline" title="io.IOBase.readline"><code class="xref py py-meth docutils literal notranslate"><span class="pre">readline()</span></code></a>
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method. If <em>n</em> is <code class="docutils literal notranslate"><span class="pre">0</span></code>, exactly one line is read, regardless of the length of
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the line. If <em>n</em> is greater than <code class="docutils literal notranslate"><span class="pre">0</span></code>, no more than <em>n</em> bytes will be read
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from the file; a partial line can be returned. In both cases, an empty string
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is returned if the end of the file is reached immediately. If <em>n</em> is less than
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<code class="docutils literal notranslate"><span class="pre">0</span></code>, however, one line is read regardless of length, but <a class="reference internal" href="../library/exceptions.html#EOFError" title="EOFError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">EOFError</span></code></a> is
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raised if the end of the file is reached immediately.</p>
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</dd></dl>
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<dl class="function">
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<dt id="c.PyFile_WriteObject">
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int <code class="descname">PyFile_WriteObject</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *obj</em>, <a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *p</em>, int<em> flags</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyFile_WriteObject" title="Permalink to this definition">¶</a></dt>
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<dd><p id="index-2">Write object <em>obj</em> to file object <em>p</em>. The only supported flag for <em>flags</em> is
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<code class="xref py py-const docutils literal notranslate"><span class="pre">Py_PRINT_RAW</span></code>; if given, the <a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-func docutils literal notranslate"><span class="pre">str()</span></code></a> of the object is written
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instead of the <a class="reference internal" href="../library/functions.html#repr" title="repr"><code class="xref py py-func docutils literal notranslate"><span class="pre">repr()</span></code></a>. Return <code class="docutils literal notranslate"><span class="pre">0</span></code> on success or <code class="docutils literal notranslate"><span class="pre">-1</span></code> on failure; the
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appropriate exception will be set.</p>
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</dd></dl>
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<dl class="function">
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<dt id="c.PyFile_WriteString">
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int <code class="descname">PyFile_WriteString</code><span class="sig-paren">(</span>const char<em> *s</em>, <a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *p</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyFile_WriteString" title="Permalink to this definition">¶</a></dt>
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<dd><p>Write string <em>s</em> to file object <em>p</em>. Return <code class="docutils literal notranslate"><span class="pre">0</span></code> on success or <code class="docutils literal notranslate"><span class="pre">-1</span></code> on
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failure; the appropriate exception will be set.</p>
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Last updated on Jul 13, 2019.
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