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<li><a class="reference internal" href="#">Parsing arguments and building values</a><ul>
<li><a class="reference internal" href="#parsing-arguments">Parsing arguments</a><ul>
<li><a class="reference internal" href="#strings-and-buffers">Strings and buffers</a></li>
<li><a class="reference internal" href="#numbers">Numbers</a></li>
<li><a class="reference internal" href="#other-objects">Other objects</a></li>
<li><a class="reference internal" href="#api-functions">API Functions</a></li>
</ul>
</li>
<li><a class="reference internal" href="#building-values">Building values</a></li>
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<section id="parsing-arguments-and-building-values">
<span id="arg-parsing"></span><h1>Parsing arguments and building values<a class="headerlink" href="#parsing-arguments-and-building-values" title="Link to this heading">¶</a></h1>
<p>These functions are useful when creating your own extension functions and
methods. Additional information and examples are available in
<a class="reference internal" href="../extending/index.html#extending-index"><span class="std std-ref">Extending and Embedding the Python Interpreter</span></a>.</p>
<p>The first three of these functions described, <a class="reference internal" href="#c.PyArg_ParseTuple" title="PyArg_ParseTuple"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyArg_ParseTuple()</span></code></a>,
<a class="reference internal" href="#c.PyArg_ParseTupleAndKeywords" title="PyArg_ParseTupleAndKeywords"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyArg_ParseTupleAndKeywords()</span></code></a>, and <a class="reference internal" href="#c.PyArg_Parse" title="PyArg_Parse"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyArg_Parse()</span></code></a>, all use <em>format
strings</em> which are used to tell the function about the expected arguments. The
format strings use the same syntax for each of these functions.</p>
<section id="parsing-arguments">
<h2>Parsing arguments<a class="headerlink" href="#parsing-arguments" title="Link to this heading">¶</a></h2>
<p>A format string consists of zero or more “format units.” A format unit
describes one Python object; it is usually a single character or a parenthesized
sequence of format units. With a few exceptions, a format unit that is not a
parenthesized sequence normally corresponds to a single address argument to
these functions. In the following description, the quoted form is the format
unit; the entry in (round) parentheses is the Python object type that matches
the format unit; and the entry in [square] brackets is the type of the C
variable(s) whose address should be passed.</p>
<section id="strings-and-buffers">
<span id="arg-parsing-string-and-buffers"></span><h3>Strings and buffers<a class="headerlink" href="#strings-and-buffers" title="Link to this heading">¶</a></h3>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>On Python 3.12 and older, the macro <code class="xref c c-macro docutils literal notranslate"><span class="pre">PY_SSIZE_T_CLEAN</span></code> must be
defined before including <code class="file docutils literal notranslate"><span class="pre">Python.h</span></code> to use all <code class="docutils literal notranslate"><span class="pre">#</span></code> variants of
formats (<code class="docutils literal notranslate"><span class="pre">s#</span></code>, <code class="docutils literal notranslate"><span class="pre">y#</span></code>, etc.) explained below.
This is not necessary on Python 3.13 and later.</p>
</div>
<p>These formats allow accessing an object as a contiguous chunk of memory.
You don’t have to provide raw storage for the returned unicode or bytes
area.</p>
<p>Unless otherwise stated, buffers are not NUL-terminated.</p>
<p>There are three ways strings and buffers can be converted to C:</p>
<ul>
<li><p>Formats such as <code class="docutils literal notranslate"><span class="pre">y*</span></code> and <code class="docutils literal notranslate"><span class="pre">s*</span></code> fill a <a class="reference internal" href="buffer.html#c.Py_buffer" title="Py_buffer"><code class="xref c c-type docutils literal notranslate"><span class="pre">Py_buffer</span></code></a> structure.
This locks the underlying buffer so that the caller can subsequently use
the buffer even inside a <a class="reference internal" href="init.html#c.Py_BEGIN_ALLOW_THREADS" title="Py_BEGIN_ALLOW_THREADS"><code class="xref c c-type docutils literal notranslate"><span class="pre">Py_BEGIN_ALLOW_THREADS</span></code></a>
block without the risk of mutable data being resized or destroyed.
As a result, <strong>you have to call</strong> <a class="reference internal" href="buffer.html#c.PyBuffer_Release" title="PyBuffer_Release"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyBuffer_Release()</span></code></a> after you have
finished processing the data (or in any early abort case).</p></li>
<li><p>The <code class="docutils literal notranslate"><span class="pre">es</span></code>, <code class="docutils literal notranslate"><span class="pre">es#</span></code>, <code class="docutils literal notranslate"><span class="pre">et</span></code> and <code class="docutils literal notranslate"><span class="pre">et#</span></code> formats allocate the result buffer.
<strong>You have to call</strong> <a class="reference internal" href="memory.html#c.PyMem_Free" title="PyMem_Free"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyMem_Free()</span></code></a> after you have finished
processing the data (or in any early abort case).</p></li>
<li><p id="c-arg-borrowed-buffer">Other formats take a <a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a> or a read-only <a class="reference internal" href="../glossary.html#term-bytes-like-object"><span class="xref std std-term">bytes-like object</span></a>,
such as <a class="reference internal" href="../library/stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a>, and provide a <code class="docutils literal notranslate"><span class="pre">const</span> <span class="pre">char</span> <span class="pre">*</span></code> pointer to
its buffer.
In this case the buffer is “borrowed”: it is managed by the corresponding
Python object, and shares the lifetime of this object.
You won’t have to release any memory yourself.</p>
<p>To ensure that the underlying buffer may be safely borrowed, the object’s
<a class="reference internal" href="typeobj.html#c.PyBufferProcs.bf_releasebuffer" title="PyBufferProcs.bf_releasebuffer"><code class="xref c c-member docutils literal notranslate"><span class="pre">PyBufferProcs.bf_releasebuffer</span></code></a> field must be <code class="docutils literal notranslate"><span class="pre">NULL</span></code>.
This disallows common mutable objects such as <a class="reference internal" href="../library/stdtypes.html#bytearray" title="bytearray"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytearray</span></code></a>,
but also some read-only objects such as <a class="reference internal" href="../library/stdtypes.html#memoryview" title="memoryview"><code class="xref py py-class docutils literal notranslate"><span class="pre">memoryview</span></code></a> of
<a class="reference internal" href="../library/stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a>.</p>
<p>Besides this <code class="docutils literal notranslate"><span class="pre">bf_releasebuffer</span></code> requirement, there is no check to verify
whether the input object is immutable (e.g. whether it would honor a request
for a writable buffer, or whether another thread can mutate the data).</p>
</li>
</ul>
<dl>
<dt><code class="docutils literal notranslate"><span class="pre">s</span></code> (<a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a>) [const char *]</dt><dd><p>Convert a Unicode object to a C pointer to a character string.
A pointer to an existing string is stored in the character pointer
variable whose address you pass. The C string is NUL-terminated.
The Python string must not contain embedded null code points; if it does,
a <a class="reference internal" href="../library/exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a> exception is raised. Unicode objects are converted
to C strings using <code class="docutils literal notranslate"><span class="pre">'utf-8'</span></code> encoding. If this conversion fails, a
<a class="reference internal" href="../library/exceptions.html#UnicodeError" title="UnicodeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">UnicodeError</span></code></a> is raised.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>This format does not accept <a class="reference internal" href="../glossary.html#term-bytes-like-object"><span class="xref std std-term">bytes-like objects</span></a>. If you want to accept
filesystem paths and convert them to C character strings, it is
preferable to use the <code class="docutils literal notranslate"><span class="pre">O&</span></code> format with <a class="reference internal" href="unicode.html#c.PyUnicode_FSConverter" title="PyUnicode_FSConverter"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyUnicode_FSConverter()</span></code></a>
as <em>converter</em>.</p>
</div>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.5: </span>Previously, <a class="reference internal" href="../library/exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TypeError</span></code></a> was raised when embedded null code points
were encountered in the Python string.</p>
</div>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">s*</span></code> (<a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a> or <a class="reference internal" href="../glossary.html#term-bytes-like-object"><span class="xref std std-term">bytes-like object</span></a>) [Py_buffer]</dt><dd><p>This format accepts Unicode objects as well as bytes-like objects.
It fills a <a class="reference internal" href="buffer.html#c.Py_buffer" title="Py_buffer"><code class="xref c c-type docutils literal notranslate"><span class="pre">Py_buffer</span></code></a> structure provided by the caller.
In this case the resulting C string may contain embedded NUL bytes.
Unicode objects are converted to C strings using <code class="docutils literal notranslate"><span class="pre">'utf-8'</span></code> encoding.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">s#</span></code> (<a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a>, read-only <a class="reference internal" href="../glossary.html#term-bytes-like-object"><span class="xref std std-term">bytes-like object</span></a>) [const char *, <a class="reference internal" href="intro.html#c.Py_ssize_t" title="Py_ssize_t"><code class="xref c c-type docutils literal notranslate"><span class="pre">Py_ssize_t</span></code></a>]</dt><dd><p>Like <code class="docutils literal notranslate"><span class="pre">s*</span></code>, except that it provides a <a class="reference internal" href="#c-arg-borrowed-buffer"><span class="std std-ref">borrowed buffer</span></a>.
The result is stored into two C variables,
the first one a pointer to a C string, the second one its length.
The string may contain embedded null bytes. Unicode objects are converted
to C strings using <code class="docutils literal notranslate"><span class="pre">'utf-8'</span></code> encoding.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">z</span></code> (<a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a> or <code class="docutils literal notranslate"><span class="pre">None</span></code>) [const char *]</dt><dd><p>Like <code class="docutils literal notranslate"><span class="pre">s</span></code>, but the Python object may also be <code class="docutils literal notranslate"><span class="pre">None</span></code>, in which case the C
pointer is set to <code class="docutils literal notranslate"><span class="pre">NULL</span></code>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">z*</span></code> (<a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a>, <a class="reference internal" href="../glossary.html#term-bytes-like-object"><span class="xref std std-term">bytes-like object</span></a> or <code class="docutils literal notranslate"><span class="pre">None</span></code>) [Py_buffer]</dt><dd><p>Like <code class="docutils literal notranslate"><span class="pre">s*</span></code>, but the Python object may also be <code class="docutils literal notranslate"><span class="pre">None</span></code>, in which case the
<code class="docutils literal notranslate"><span class="pre">buf</span></code> member of the <a class="reference internal" href="buffer.html#c.Py_buffer" title="Py_buffer"><code class="xref c c-type docutils literal notranslate"><span class="pre">Py_buffer</span></code></a> structure is set to <code class="docutils literal notranslate"><span class="pre">NULL</span></code>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">z#</span></code> (<a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a>, read-only <a class="reference internal" href="../glossary.html#term-bytes-like-object"><span class="xref std std-term">bytes-like object</span></a> or <code class="docutils literal notranslate"><span class="pre">None</span></code>) [const char *, <a class="reference internal" href="intro.html#c.Py_ssize_t" title="Py_ssize_t"><code class="xref c c-type docutils literal notranslate"><span class="pre">Py_ssize_t</span></code></a>]</dt><dd><p>Like <code class="docutils literal notranslate"><span class="pre">s#</span></code>, but the Python object may also be <code class="docutils literal notranslate"><span class="pre">None</span></code>, in which case the C
pointer is set to <code class="docutils literal notranslate"><span class="pre">NULL</span></code>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">y</span></code> (read-only <a class="reference internal" href="../glossary.html#term-bytes-like-object"><span class="xref std std-term">bytes-like object</span></a>) [const char *]</dt><dd><p>This format converts a bytes-like object to a C pointer to a
<a class="reference internal" href="#c-arg-borrowed-buffer"><span class="std std-ref">borrowed</span></a> character string;
it does not accept Unicode objects. The bytes buffer must not
contain embedded null bytes; if it does, a <a class="reference internal" href="../library/exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a>
exception is raised.</p>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.5: </span>Previously, <a class="reference internal" href="../library/exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TypeError</span></code></a> was raised when embedded null bytes were
encountered in the bytes buffer.</p>
</div>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">y*</span></code> (<a class="reference internal" href="../glossary.html#term-bytes-like-object"><span class="xref std std-term">bytes-like object</span></a>) [Py_buffer]</dt><dd><p>This variant on <code class="docutils literal notranslate"><span class="pre">s*</span></code> doesn’t accept Unicode objects, only
bytes-like objects. <strong>This is the recommended way to accept
binary data.</strong></p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">y#</span></code> (read-only <a class="reference internal" href="../glossary.html#term-bytes-like-object"><span class="xref std std-term">bytes-like object</span></a>) [const char *, <a class="reference internal" href="intro.html#c.Py_ssize_t" title="Py_ssize_t"><code class="xref c c-type docutils literal notranslate"><span class="pre">Py_ssize_t</span></code></a>]</dt><dd><p>This variant on <code class="docutils literal notranslate"><span class="pre">s#</span></code> doesn’t accept Unicode objects, only bytes-like
objects.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">S</span></code> (<a class="reference internal" href="../library/stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a>) [PyBytesObject *]</dt><dd><p>Requires that the Python object is a <a class="reference internal" href="../library/stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a> object, without
attempting any conversion. Raises <a class="reference internal" href="../library/exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TypeError</span></code></a> if the object is not
a bytes object. The C variable may also be declared as <span class="c-expr sig sig-inline c"><a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n">PyObject</span></a><span class="p">*</span></span>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">Y</span></code> (<a class="reference internal" href="../library/stdtypes.html#bytearray" title="bytearray"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytearray</span></code></a>) [PyByteArrayObject *]</dt><dd><p>Requires that the Python object is a <a class="reference internal" href="../library/stdtypes.html#bytearray" title="bytearray"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytearray</span></code></a> object, without
attempting any conversion. Raises <a class="reference internal" href="../library/exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TypeError</span></code></a> if the object is not
a <a class="reference internal" href="../library/stdtypes.html#bytearray" title="bytearray"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytearray</span></code></a> object. The C variable may also be declared as <span class="c-expr sig sig-inline c"><a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n">PyObject</span></a><span class="p">*</span></span>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">U</span></code> (<a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a>) [PyObject *]</dt><dd><p>Requires that the Python object is a Unicode object, without attempting
any conversion. Raises <a class="reference internal" href="../library/exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TypeError</span></code></a> if the object is not a Unicode
object. The C variable may also be declared as <span class="c-expr sig sig-inline c"><a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n">PyObject</span></a><span class="p">*</span></span>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">w*</span></code> (read-write <a class="reference internal" href="../glossary.html#term-bytes-like-object"><span class="xref std std-term">bytes-like object</span></a>) [Py_buffer]</dt><dd><p>This format accepts any object which implements the read-write buffer
interface. It fills a <a class="reference internal" href="buffer.html#c.Py_buffer" title="Py_buffer"><code class="xref c c-type docutils literal notranslate"><span class="pre">Py_buffer</span></code></a> structure provided by the caller.
The buffer may contain embedded null bytes. The caller have to call
<a class="reference internal" href="buffer.html#c.PyBuffer_Release" title="PyBuffer_Release"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyBuffer_Release()</span></code></a> when it is done with the buffer.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">es</span></code> (<a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a>) [const char *encoding, char **buffer]</dt><dd><p>This variant on <code class="docutils literal notranslate"><span class="pre">s</span></code> is used for encoding Unicode into a character buffer.
It only works for encoded data without embedded NUL bytes.</p>
<p>This format requires two arguments. The first is only used as input, and
must be a <span class="c-expr sig sig-inline c"><span class="k">const</span><span class="w"> </span><span class="kt">char</span><span class="p">*</span></span> which points to the name of an encoding as a
NUL-terminated string, or <code class="docutils literal notranslate"><span class="pre">NULL</span></code>, in which case <code class="docutils literal notranslate"><span class="pre">'utf-8'</span></code> encoding is used.
An exception is raised if the named encoding is not known to Python. The
second argument must be a <span class="c-expr sig sig-inline c"><span class="kt">char</span><span class="p">*</span><span class="p">*</span></span>; the value of the pointer it
references will be set to a buffer with the contents of the argument text.
The text will be encoded in the encoding specified by the first argument.</p>
<p><a class="reference internal" href="#c.PyArg_ParseTuple" title="PyArg_ParseTuple"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyArg_ParseTuple()</span></code></a> will allocate a buffer of the needed size, copy the
encoded data into this buffer and adjust <em>*buffer</em> to reference the newly
allocated storage. The caller is responsible for calling <a class="reference internal" href="memory.html#c.PyMem_Free" title="PyMem_Free"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyMem_Free()</span></code></a> to
free the allocated buffer after use.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">et</span></code> (<a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a>, <a class="reference internal" href="../library/stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a> or <a class="reference internal" href="../library/stdtypes.html#bytearray" title="bytearray"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytearray</span></code></a>) [const char *encoding, char **buffer]</dt><dd><p>Same as <code class="docutils literal notranslate"><span class="pre">es</span></code> except that byte string objects are passed through without
recoding them. Instead, the implementation assumes that the byte string object uses
the encoding passed in as parameter.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">es#</span></code> (<a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a>) [const char *encoding, char **buffer, <a class="reference internal" href="intro.html#c.Py_ssize_t" title="Py_ssize_t"><code class="xref c c-type docutils literal notranslate"><span class="pre">Py_ssize_t</span></code></a> *buffer_length]</dt><dd><p>This variant on <code class="docutils literal notranslate"><span class="pre">s#</span></code> is used for encoding Unicode into a character buffer.
Unlike the <code class="docutils literal notranslate"><span class="pre">es</span></code> format, this variant allows input data which contains NUL
characters.</p>
<p>It requires three arguments. The first is only used as input, and must be a
<span class="c-expr sig sig-inline c"><span class="k">const</span><span class="w"> </span><span class="kt">char</span><span class="p">*</span></span> which points to the name of an encoding as a
NUL-terminated string, or <code class="docutils literal notranslate"><span class="pre">NULL</span></code>, in which case <code class="docutils literal notranslate"><span class="pre">'utf-8'</span></code> encoding is used.
An exception is raised if the named encoding is not known to Python. The
second argument must be a <span class="c-expr sig sig-inline c"><span class="kt">char</span><span class="p">*</span><span class="p">*</span></span>; the value of the pointer it
references will be set to a buffer with the contents of the argument text.
The text will be encoded in the encoding specified by the first argument.
The third argument must be a pointer to an integer; the referenced integer
will be set to the number of bytes in the output buffer.</p>
<p>There are two modes of operation:</p>
<p>If <em>*buffer</em> points a <code class="docutils literal notranslate"><span class="pre">NULL</span></code> pointer, the function will allocate a buffer of
the needed size, copy the encoded data into this buffer and set <em>*buffer</em> to
reference the newly allocated storage. The caller is responsible for calling
<a class="reference internal" href="memory.html#c.PyMem_Free" title="PyMem_Free"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyMem_Free()</span></code></a> to free the allocated buffer after usage.</p>
<p>If <em>*buffer</em> points to a non-<code class="docutils literal notranslate"><span class="pre">NULL</span></code> pointer (an already allocated buffer),
<a class="reference internal" href="#c.PyArg_ParseTuple" title="PyArg_ParseTuple"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyArg_ParseTuple()</span></code></a> will use this location as the buffer and interpret the
initial value of <em>*buffer_length</em> as the buffer size. It will then copy the
encoded data into the buffer and NUL-terminate it. If the buffer is not large
enough, a <a class="reference internal" href="../library/exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a> will be set.</p>
<p>In both cases, <em>*buffer_length</em> is set to the length of the encoded data
without the trailing NUL byte.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">et#</span></code> (<a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a>, <a class="reference internal" href="../library/stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a> or <a class="reference internal" href="../library/stdtypes.html#bytearray" title="bytearray"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytearray</span></code></a>) [const char *encoding, char **buffer, <a class="reference internal" href="intro.html#c.Py_ssize_t" title="Py_ssize_t"><code class="xref c c-type docutils literal notranslate"><span class="pre">Py_ssize_t</span></code></a> *buffer_length]</dt><dd><p>Same as <code class="docutils literal notranslate"><span class="pre">es#</span></code> except that byte string objects are passed through without recoding
them. Instead, the implementation assumes that the byte string object uses the
encoding passed in as parameter.</p>
</dd>
</dl>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.12: </span><code class="docutils literal notranslate"><span class="pre">u</span></code>, <code class="docutils literal notranslate"><span class="pre">u#</span></code>, <code class="docutils literal notranslate"><span class="pre">Z</span></code>, and <code class="docutils literal notranslate"><span class="pre">Z#</span></code> are removed because they used a legacy
<code class="docutils literal notranslate"><span class="pre">Py_UNICODE*</span></code> representation.</p>
</div>
</section>
<section id="numbers">
<h3>Numbers<a class="headerlink" href="#numbers" title="Link to this heading">¶</a></h3>
<p>These formats allow representing Python numbers or single characters as C numbers.
Formats that require <a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>, <a class="reference internal" href="../library/functions.html#float" title="float"><code class="xref py py-class docutils literal notranslate"><span class="pre">float</span></code></a> or <a class="reference internal" href="../library/functions.html#complex" title="complex"><code class="xref py py-class docutils literal notranslate"><span class="pre">complex</span></code></a> can
also use the corresponding special methods <a class="reference internal" href="../reference/datamodel.html#object.__index__" title="object.__index__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__index__()</span></code></a>,
<a class="reference internal" href="../reference/datamodel.html#object.__float__" title="object.__float__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__float__()</span></code></a> or <a class="reference internal" href="../reference/datamodel.html#object.__complex__" title="object.__complex__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__complex__()</span></code></a> to convert
the Python object to the required type.</p>
<p>For signed integer formats, <a class="reference internal" href="../library/exceptions.html#OverflowError" title="OverflowError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">OverflowError</span></code></a> is raised if the value
is out of range for the C type.
For unsigned integer formats, no range checking is done — the
most significant bits are silently truncated when the receiving field is too
small to receive the value.</p>
<dl>
<dt><code class="docutils literal notranslate"><span class="pre">b</span></code> (<a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>) [unsigned char]</dt><dd><p>Convert a nonnegative Python integer to an unsigned tiny integer, stored in a C
<span class="c-expr sig sig-inline c"><span class="kt">unsigned</span><span class="w"> </span><span class="kt">char</span></span>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">B</span></code> (<a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>) [unsigned char]</dt><dd><p>Convert a Python integer to a tiny integer without overflow checking, stored in a C
<span class="c-expr sig sig-inline c"><span class="kt">unsigned</span><span class="w"> </span><span class="kt">char</span></span>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">h</span></code> (<a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>) [short int]</dt><dd><p>Convert a Python integer to a C <span class="c-expr sig sig-inline c"><span class="kt">short</span><span class="w"> </span><span class="kt">int</span></span>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">H</span></code> (<a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>) [unsigned short int]</dt><dd><p>Convert a Python integer to a C <span class="c-expr sig sig-inline c"><span class="kt">unsigned</span><span class="w"> </span><span class="kt">short</span><span class="w"> </span><span class="kt">int</span></span>, without overflow
checking.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">i</span></code> (<a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>) [int]</dt><dd><p>Convert a Python integer to a plain C <span class="c-expr sig sig-inline c"><span class="kt">int</span></span>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">I</span></code> (<a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>) [unsigned int]</dt><dd><p>Convert a Python integer to a C <span class="c-expr sig sig-inline c"><span class="kt">unsigned</span><span class="w"> </span><span class="kt">int</span></span>, without overflow
checking.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">l</span></code> (<a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>) [long int]</dt><dd><p>Convert a Python integer to a C <span class="c-expr sig sig-inline c"><span class="kt">long</span><span class="w"> </span><span class="kt">int</span></span>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">k</span></code> (<a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>) [unsigned long]</dt><dd><p>Convert a Python integer to a C <span class="c-expr sig sig-inline c"><span class="kt">unsigned</span><span class="w"> </span><span class="kt">long</span></span> without
overflow checking.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">L</span></code> (<a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>) [long long]</dt><dd><p>Convert a Python integer to a C <span class="c-expr sig sig-inline c"><span class="kt">long</span><span class="w"> </span><span class="kt">long</span></span>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">K</span></code> (<a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>) [unsigned long long]</dt><dd><p>Convert a Python integer to a C <span class="c-expr sig sig-inline c"><span class="kt">unsigned</span><span class="w"> </span><span class="kt">long</span><span class="w"> </span><span class="kt">long</span></span>
without overflow checking.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">n</span></code> (<a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>) [<a class="reference internal" href="intro.html#c.Py_ssize_t" title="Py_ssize_t"><code class="xref c c-type docutils literal notranslate"><span class="pre">Py_ssize_t</span></code></a>]</dt><dd><p>Convert a Python integer to a C <a class="reference internal" href="intro.html#c.Py_ssize_t" title="Py_ssize_t"><code class="xref c c-type docutils literal notranslate"><span class="pre">Py_ssize_t</span></code></a>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">c</span></code> (<a class="reference internal" href="../library/stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a> or <a class="reference internal" href="../library/stdtypes.html#bytearray" title="bytearray"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytearray</span></code></a> of length 1) [char]</dt><dd><p>Convert a Python byte, represented as a <a class="reference internal" href="../library/stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a> or
<a class="reference internal" href="../library/stdtypes.html#bytearray" title="bytearray"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytearray</span></code></a> object of length 1, to a C <span class="c-expr sig sig-inline c"><span class="kt">char</span></span>.</p>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.3: </span>Allow <a class="reference internal" href="../library/stdtypes.html#bytearray" title="bytearray"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytearray</span></code></a> objects.</p>
</div>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">C</span></code> (<a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a> of length 1) [int]</dt><dd><p>Convert a Python character, represented as a <a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a> object of
length 1, to a C <span class="c-expr sig sig-inline c"><span class="kt">int</span></span>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">f</span></code> (<a class="reference internal" href="../library/functions.html#float" title="float"><code class="xref py py-class docutils literal notranslate"><span class="pre">float</span></code></a>) [float]</dt><dd><p>Convert a Python floating-point number to a C <span class="c-expr sig sig-inline c"><span class="kt">float</span></span>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">d</span></code> (<a class="reference internal" href="../library/functions.html#float" title="float"><code class="xref py py-class docutils literal notranslate"><span class="pre">float</span></code></a>) [double]</dt><dd><p>Convert a Python floating-point number to a C <span class="c-expr sig sig-inline c"><span class="kt">double</span></span>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">D</span></code> (<a class="reference internal" href="../library/functions.html#complex" title="complex"><code class="xref py py-class docutils literal notranslate"><span class="pre">complex</span></code></a>) [Py_complex]</dt><dd><p>Convert a Python complex number to a C <a class="reference internal" href="complex.html#c.Py_complex" title="Py_complex"><code class="xref c c-type docutils literal notranslate"><span class="pre">Py_complex</span></code></a> structure.</p>
</dd>
</dl>
</section>
<section id="other-objects">
<h3>Other objects<a class="headerlink" href="#other-objects" title="Link to this heading">¶</a></h3>
<dl class="simple">
<dt><code class="docutils literal notranslate"><span class="pre">O</span></code> (object) [PyObject *]</dt><dd><p>Store a Python object (without any conversion) in a C object pointer. The C
program thus receives the actual object that was passed. A new
<a class="reference internal" href="../glossary.html#term-strong-reference"><span class="xref std std-term">strong reference</span></a> to the object is not created
(i.e. its reference count is not increased).
The pointer stored is not <code class="docutils literal notranslate"><span class="pre">NULL</span></code>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">O!</span></code> (object) [<em>typeobject</em>, PyObject *]</dt><dd><p>Store a Python object in a C object pointer. This is similar to <code class="docutils literal notranslate"><span class="pre">O</span></code>, but
takes two C arguments: the first is the address of a Python type object, the
second is the address of the C variable (of type <span class="c-expr sig sig-inline c"><a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n">PyObject</span></a><span class="p">*</span></span>) into which
the object pointer is stored. If the Python object does not have the required
type, <a class="reference internal" href="../library/exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TypeError</span></code></a> is raised.</p>
</dd>
</dl>
<dl id="o-ampersand">
<dt><code class="docutils literal notranslate"><span class="pre">O&</span></code> (object) [<em>converter</em>, <em>address</em>]</dt><dd><p>Convert a Python object to a C variable through a <em>converter</em> function. This
takes two arguments: the first is a function, the second is the address of a C
variable (of arbitrary type), converted to <span class="c-expr sig sig-inline c"><span class="kt">void</span><span class="p">*</span></span>. The <em>converter</em>
function in turn is called as follows:</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n">status</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">converter</span><span class="p">(</span><span class="n">object</span><span class="p">,</span><span class="w"> </span><span class="n">address</span><span class="p">);</span>
</pre></div>
</div>
<p>where <em>object</em> is the Python object to be converted and <em>address</em> is the
<span class="c-expr sig sig-inline c"><span class="kt">void</span><span class="p">*</span></span> argument that was passed to the <code class="docutils literal notranslate"><span class="pre">PyArg_Parse*</span></code> function.
The returned <em>status</em> should be <code class="docutils literal notranslate"><span class="pre">1</span></code> for a successful conversion and <code class="docutils literal notranslate"><span class="pre">0</span></code> if
the conversion has failed. When the conversion fails, the <em>converter</em> function
should raise an exception and leave the content of <em>address</em> unmodified.</p>
<p id="c.Py_CLEANUP_SUPPORTED">If the <em>converter</em> returns <code class="xref c c-macro docutils literal notranslate"><span class="pre">Py_CLEANUP_SUPPORTED</span></code>, it may get called a
second time if the argument parsing eventually fails, giving the converter a
chance to release any memory that it had already allocated. In this second
call, the <em>object</em> parameter will be <code class="docutils literal notranslate"><span class="pre">NULL</span></code>; <em>address</em> will have the same value
as in the original call.</p>
<p>Examples of converters: <a class="reference internal" href="unicode.html#c.PyUnicode_FSConverter" title="PyUnicode_FSConverter"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyUnicode_FSConverter()</span></code></a> and
<a class="reference internal" href="unicode.html#c.PyUnicode_FSDecoder" title="PyUnicode_FSDecoder"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyUnicode_FSDecoder()</span></code></a>.</p>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.1: </span><code class="xref c c-macro docutils literal notranslate"><span class="pre">Py_CLEANUP_SUPPORTED</span></code> was added.</p>
</div>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">p</span></code> (<a class="reference internal" href="../library/functions.html#bool" title="bool"><code class="xref py py-class docutils literal notranslate"><span class="pre">bool</span></code></a>) [int]</dt><dd><p>Tests the value passed in for truth (a boolean <strong>p</strong>redicate) and converts
the result to its equivalent C true/false integer value.
Sets the int to <code class="docutils literal notranslate"><span class="pre">1</span></code> if the expression was true and <code class="docutils literal notranslate"><span class="pre">0</span></code> if it was false.
This accepts any valid Python value. See <a class="reference internal" href="../library/stdtypes.html#truth"><span class="std std-ref">Truth Value Testing</span></a> for more
information about how Python tests values for truth.</p>
<div class="versionadded">
<p><span class="versionmodified added">Added in version 3.3.</span></p>
</div>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">(items)</span></code> (<a class="reference internal" href="../library/stdtypes.html#tuple" title="tuple"><code class="xref py py-class docutils literal notranslate"><span class="pre">tuple</span></code></a>) [<em>matching-items</em>]</dt><dd><p>The object must be a Python sequence whose length is the number of format units
in <em>items</em>. The C arguments must correspond to the individual format units in
<em>items</em>. Format units for sequences may be nested.</p>
</dd>
</dl>
<p>A few other characters have a meaning in a format string. These may not occur
inside nested parentheses. They are:</p>
<dl>
<dt><code class="docutils literal notranslate"><span class="pre">|</span></code></dt><dd><p>Indicates that the remaining arguments in the Python argument list are optional.
The C variables corresponding to optional arguments should be initialized to
their default value — when an optional argument is not specified,
<a class="reference internal" href="#c.PyArg_ParseTuple" title="PyArg_ParseTuple"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyArg_ParseTuple()</span></code></a> does not touch the contents of the corresponding C
variable(s).</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">$</span></code></dt><dd><p><a class="reference internal" href="#c.PyArg_ParseTupleAndKeywords" title="PyArg_ParseTupleAndKeywords"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyArg_ParseTupleAndKeywords()</span></code></a> only:
Indicates that the remaining arguments in the Python argument list are
keyword-only. Currently, all keyword-only arguments must also be optional
arguments, so <code class="docutils literal notranslate"><span class="pre">|</span></code> must always be specified before <code class="docutils literal notranslate"><span class="pre">$</span></code> in the format
string.</p>
<div class="versionadded">
<p><span class="versionmodified added">Added in version 3.3.</span></p>
</div>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">:</span></code></dt><dd><p>The list of format units ends here; the string after the colon is used as the
function name in error messages (the “associated value” of the exception that
<a class="reference internal" href="#c.PyArg_ParseTuple" title="PyArg_ParseTuple"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyArg_ParseTuple()</span></code></a> raises).</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">;</span></code></dt><dd><p>The list of format units ends here; the string after the semicolon is used as
the error message <em>instead</em> of the default error message. <code class="docutils literal notranslate"><span class="pre">:</span></code> and <code class="docutils literal notranslate"><span class="pre">;</span></code>
mutually exclude each other.</p>
</dd>
</dl>
<p>Note that any Python object references which are provided to the caller are
<em>borrowed</em> references; do not release them
(i.e. do not decrement their reference count)!</p>
<p>Additional arguments passed to these functions must be addresses of variables
whose type is determined by the format string; these are used to store values
from the input tuple. There are a few cases, as described in the list of format
units above, where these parameters are used as input values; they should match
what is specified for the corresponding format unit in that case.</p>
<p>For the conversion to succeed, the <em>arg</em> object must match the format
and the format must be exhausted. On success, the
<code class="docutils literal notranslate"><span class="pre">PyArg_Parse*</span></code> functions return true, otherwise they return
false and raise an appropriate exception. When the
<code class="docutils literal notranslate"><span class="pre">PyArg_Parse*</span></code> functions fail due to conversion failure in one
of the format units, the variables at the addresses corresponding to that
and the following format units are left untouched.</p>
</section>
<section id="api-functions">
<h3>API Functions<a class="headerlink" href="#api-functions" title="Link to this heading">¶</a></h3>
<dl class="c function">
<dt class="sig sig-object c" id="c.PyArg_ParseTuple">
<span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyArg_ParseTuple</span></span></span><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">args</span></span>, <span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">format</span></span>, <span class="p"><span class="pre">...</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyArg_ParseTuple" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p>Parse the parameters of a function that takes only positional parameters into
local variables. Returns true on success; on failure, it returns false and
raises the appropriate exception.</p>
</dd></dl>
<dl class="c function">
<dt class="sig sig-object c" id="c.PyArg_VaParse">
<span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyArg_VaParse</span></span></span><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">args</span></span>, <span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">format</span></span>, <span class="n"><span class="pre">va_list</span></span><span class="w"> </span><span class="n"><span class="pre">vargs</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyArg_VaParse" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p>Identical to <a class="reference internal" href="#c.PyArg_ParseTuple" title="PyArg_ParseTuple"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyArg_ParseTuple()</span></code></a>, except that it accepts a va_list rather
than a variable number of arguments.</p>
</dd></dl>
<dl class="c function">
<dt class="sig sig-object c" id="c.PyArg_ParseTupleAndKeywords">
<span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyArg_ParseTupleAndKeywords</span></span></span><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">args</span></span>, <a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">kw</span></span>, <span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">format</span></span>, <span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">keywords</span></span>, <span class="p"><span class="pre">...</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyArg_ParseTupleAndKeywords" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p>Parse the parameters of a function that takes both positional and keyword
parameters into local variables.
The <em>keywords</em> argument is a <code class="docutils literal notranslate"><span class="pre">NULL</span></code>-terminated array of keyword parameter
names specified as null-terminated ASCII or UTF-8 encoded C strings.
Empty names denote
<a class="reference internal" href="../glossary.html#positional-only-parameter"><span class="std std-ref">positional-only parameters</span></a>.
Returns true on success; on failure, it returns false and raises the
appropriate exception.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>The <em>keywords</em> parameter declaration is <span class="c-expr sig sig-inline c"><span class="kt">char</span><span class="w"> </span><span class="p">*</span><span class="k">const</span><span class="p">*</span></span> in C and
<span class="c-expr sig sig-inline c"><span class="k">const</span><span class="w"> </span><span class="kt">char</span><span class="w"> </span><span class="p">*</span><span class="k">const</span><span class="p">*</span></span> in C++.
This can be overridden with the <a class="reference internal" href="#c.PY_CXX_CONST" title="PY_CXX_CONST"><code class="xref c c-macro docutils literal notranslate"><span class="pre">PY_CXX_CONST</span></code></a> macro.</p>
</div>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.6: </span>Added support for <a class="reference internal" href="../glossary.html#positional-only-parameter"><span class="std std-ref">positional-only parameters</span></a>.</p>
</div>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.13: </span>The <em>keywords</em> parameter has now type <span class="c-expr sig sig-inline c"><span class="kt">char</span><span class="w"> </span><span class="p">*</span><span class="k">const</span><span class="p">*</span></span> in C and
<span class="c-expr sig sig-inline c"><span class="k">const</span><span class="w"> </span><span class="kt">char</span><span class="w"> </span><span class="p">*</span><span class="k">const</span><span class="p">*</span></span> in C++, instead of <span class="c-expr sig sig-inline c"><span class="kt">char</span><span class="p">*</span><span class="p">*</span></span>.
Added support for non-ASCII keyword parameter names.</p>
</div>
</dd></dl>
<dl class="c function">
<dt class="sig sig-object c" id="c.PyArg_VaParseTupleAndKeywords">
<span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyArg_VaParseTupleAndKeywords</span></span></span><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">args</span></span>, <a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">kw</span></span>, <span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">format</span></span>, <span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">keywords</span></span>, <span class="n"><span class="pre">va_list</span></span><span class="w"> </span><span class="n"><span class="pre">vargs</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyArg_VaParseTupleAndKeywords" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p>Identical to <a class="reference internal" href="#c.PyArg_ParseTupleAndKeywords" title="PyArg_ParseTupleAndKeywords"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyArg_ParseTupleAndKeywords()</span></code></a>, except that it accepts a
va_list rather than a variable number of arguments.</p>
</dd></dl>
<dl class="c function">
<dt class="sig sig-object c" id="c.PyArg_ValidateKeywordArguments">
<span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyArg_ValidateKeywordArguments</span></span></span><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="p"><span class="pre">*</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyArg_ValidateKeywordArguments" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p>Ensure that the keys in the keywords argument dictionary are strings. This
is only needed if <a class="reference internal" href="#c.PyArg_ParseTupleAndKeywords" title="PyArg_ParseTupleAndKeywords"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyArg_ParseTupleAndKeywords()</span></code></a> is not used, since the
latter already does this check.</p>
<div class="versionadded">
<p><span class="versionmodified added">Added in version 3.2.</span></p>
</div>
</dd></dl>
<dl class="c function">
<dt class="sig sig-object c" id="c.PyArg_Parse">
<span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyArg_Parse</span></span></span><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">args</span></span>, <span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">format</span></span>, <span class="p"><span class="pre">...</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyArg_Parse" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p>Parse the parameter of a function that takes a single positional parameter
into a local variable. Returns true on success; on failure, it returns
false and raises the appropriate exception.</p>
<p>Example:</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="c1">// Function using METH_O calling convention</span>
<span class="k">static</span><span class="w"> </span><span class="n">PyObject</span><span class="o">*</span>
<span class="nf">my_function</span><span class="p">(</span><span class="n">PyObject</span><span class="w"> </span><span class="o">*</span><span class="n">module</span><span class="p">,</span><span class="w"> </span><span class="n">PyObject</span><span class="w"> </span><span class="o">*</span><span class="n">arg</span><span class="p">)</span>
<span class="p">{</span>
<span class="w"> </span><span class="kt">int</span><span class="w"> </span><span class="n">value</span><span class="p">;</span>
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="o">!</span><span class="n">PyArg_Parse</span><span class="p">(</span><span class="n">arg</span><span class="p">,</span><span class="w"> </span><span class="s">"i:my_function"</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">value</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span>
<span class="w"> </span><span class="p">}</span>
<span class="w"> </span><span class="c1">// ... use value ...</span>
<span class="p">}</span>
</pre></div>
</div>
</dd></dl>
<dl class="c function">
<dt class="sig sig-object c" id="c.PyArg_UnpackTuple">
<span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyArg_UnpackTuple</span></span></span><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">args</span></span>, <span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">name</span></span>, <a class="reference internal" href="intro.html#c.Py_ssize_t" title="Py_ssize_t"><span class="n"><span class="pre">Py_ssize_t</span></span></a><span class="w"> </span><span class="n"><span class="pre">min</span></span>, <a class="reference internal" href="intro.html#c.Py_ssize_t" title="Py_ssize_t"><span class="n"><span class="pre">Py_ssize_t</span></span></a><span class="w"> </span><span class="n"><span class="pre">max</span></span>, <span class="p"><span class="pre">...</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyArg_UnpackTuple" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p>A simpler form of parameter retrieval which does not use a format string to
specify the types of the arguments. Functions which use this method to retrieve
their parameters should be declared as <a class="reference internal" href="structures.html#c.METH_VARARGS" title="METH_VARARGS"><code class="xref c c-macro docutils literal notranslate"><span class="pre">METH_VARARGS</span></code></a> in function or
method tables. The tuple containing the actual parameters should be passed as
<em>args</em>; it must actually be a tuple. The length of the tuple must be at least
<em>min</em> and no more than <em>max</em>; <em>min</em> and <em>max</em> may be equal. Additional
arguments must be passed to the function, each of which should be a pointer to a
<span class="c-expr sig sig-inline c"><a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n">PyObject</span></a><span class="p">*</span></span> variable; these will be filled in with the values from
<em>args</em>; they will contain <a class="reference internal" href="../glossary.html#term-borrowed-reference"><span class="xref std std-term">borrowed references</span></a>.
The variables which correspond
to optional parameters not given by <em>args</em> will not be filled in; these should
be initialized by the caller. This function returns true on success and false if
<em>args</em> is not a tuple or contains the wrong number of elements; an exception
will be set if there was a failure.</p>
<p>This is an example of the use of this function, taken from the sources for the
<code class="xref py py-mod docutils literal notranslate"><span class="pre">_weakref</span></code> helper module for weak references:</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="k">static</span><span class="w"> </span><span class="n">PyObject</span><span class="w"> </span><span class="o">*</span>
<span class="nf">weakref_ref</span><span class="p">(</span><span class="n">PyObject</span><span class="w"> </span><span class="o">*</span><span class="n">self</span><span class="p">,</span><span class="w"> </span><span class="n">PyObject</span><span class="w"> </span><span class="o">*</span><span class="n">args</span><span class="p">)</span>
<span class="p">{</span>
<span class="w"> </span><span class="n">PyObject</span><span class="w"> </span><span class="o">*</span><span class="n">object</span><span class="p">;</span>
<span class="w"> </span><span class="n">PyObject</span><span class="w"> </span><span class="o">*</span><span class="n">callback</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span>
<span class="w"> </span><span class="n">PyObject</span><span class="w"> </span><span class="o">*</span><span class="n">result</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span>
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">PyArg_UnpackTuple</span><span class="p">(</span><span class="n">args</span><span class="p">,</span><span class="w"> </span><span class="s">"ref"</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">object</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">callback</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="n">result</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">PyWeakref_NewRef</span><span class="p">(</span><span class="n">object</span><span class="p">,</span><span class="w"> </span><span class="n">callback</span><span class="p">);</span>
<span class="w"> </span><span class="p">}</span>
<span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">result</span><span class="p">;</span>
<span class="p">}</span>
</pre></div>
</div>
<p>The call to <a class="reference internal" href="#c.PyArg_UnpackTuple" title="PyArg_UnpackTuple"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyArg_UnpackTuple()</span></code></a> in this example is entirely equivalent to
this call to <a class="reference internal" href="#c.PyArg_ParseTuple" title="PyArg_ParseTuple"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyArg_ParseTuple()</span></code></a>:</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n">PyArg_ParseTuple</span><span class="p">(</span><span class="n">args</span><span class="p">,</span><span class="w"> </span><span class="s">"O|O:ref"</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">object</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">callback</span><span class="p">)</span>
</pre></div>
</div>
</dd></dl>
<dl class="c macro">
<dt class="sig sig-object c" id="c.PY_CXX_CONST">
<span class="sig-name descname"><span class="n"><span class="pre">PY_CXX_CONST</span></span></span><a class="headerlink" href="#c.PY_CXX_CONST" title="Link to this definition">¶</a><br /></dt>
<dd><p>The value to be inserted, if any, before <span class="c-expr sig sig-inline c"><span class="kt">char</span><span class="w"> </span><span class="p">*</span><span class="k">const</span><span class="p">*</span></span>
in the <em>keywords</em> parameter declaration of
<a class="reference internal" href="#c.PyArg_ParseTupleAndKeywords" title="PyArg_ParseTupleAndKeywords"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyArg_ParseTupleAndKeywords()</span></code></a> and
<a class="reference internal" href="#c.PyArg_VaParseTupleAndKeywords" title="PyArg_VaParseTupleAndKeywords"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyArg_VaParseTupleAndKeywords()</span></code></a>.
Default empty for C and <code class="docutils literal notranslate"><span class="pre">const</span></code> for C++
(<span class="c-expr sig sig-inline c"><span class="k">const</span><span class="w"> </span><span class="kt">char</span><span class="w"> </span><span class="p">*</span><span class="k">const</span><span class="p">*</span></span>).
To override, define it to the desired value before including
<code class="file docutils literal notranslate"><span class="pre">Python.h</span></code>.</p>
<div class="versionadded">
<p><span class="versionmodified added">Added in version 3.13.</span></p>
</div>
</dd></dl>
</section>
</section>
<section id="building-values">
<h2>Building values<a class="headerlink" href="#building-values" title="Link to this heading">¶</a></h2>
<dl class="c function">
<dt class="sig sig-object c" id="c.Py_BuildValue">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="sig-name descname"><span class="n"><span class="pre">Py_BuildValue</span></span></span><span class="sig-paren">(</span><span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">format</span></span>, <span class="p"><span class="pre">...</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.Py_BuildValue" title="Link to this definition">¶</a><br /></dt>
<dd><em class="refcount return_new_ref">Return value: New reference.</em><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p>Create a new value based on a format string similar to those accepted by the
<code class="docutils literal notranslate"><span class="pre">PyArg_Parse*</span></code> family of functions and a sequence of values. Returns
the value or <code class="docutils literal notranslate"><span class="pre">NULL</span></code> in the case of an error; an exception will be raised if
<code class="docutils literal notranslate"><span class="pre">NULL</span></code> is returned.</p>
<p><a class="reference internal" href="#c.Py_BuildValue" title="Py_BuildValue"><code class="xref c c-func docutils literal notranslate"><span class="pre">Py_BuildValue()</span></code></a> does not always build a tuple. It builds a tuple only if
its format string contains two or more format units. If the format string is
empty, it returns <code class="docutils literal notranslate"><span class="pre">None</span></code>; if it contains exactly one format unit, it returns
whatever object is described by that format unit. To force it to return a tuple
of size 0 or one, parenthesize the format string.</p>
<p>When memory buffers are passed as parameters to supply data to build objects, as
for the <code class="docutils literal notranslate"><span class="pre">s</span></code> and <code class="docutils literal notranslate"><span class="pre">s#</span></code> formats, the required data is copied. Buffers provided
by the caller are never referenced by the objects created by
<a class="reference internal" href="#c.Py_BuildValue" title="Py_BuildValue"><code class="xref c c-func docutils literal notranslate"><span class="pre">Py_BuildValue()</span></code></a>. In other words, if your code invokes <code class="xref c c-func docutils literal notranslate"><span class="pre">malloc()</span></code>
and passes the allocated memory to <a class="reference internal" href="#c.Py_BuildValue" title="Py_BuildValue"><code class="xref c c-func docutils literal notranslate"><span class="pre">Py_BuildValue()</span></code></a>, your code is
responsible for calling <code class="xref c c-func docutils literal notranslate"><span class="pre">free()</span></code> for that memory once
<a class="reference internal" href="#c.Py_BuildValue" title="Py_BuildValue"><code class="xref c c-func docutils literal notranslate"><span class="pre">Py_BuildValue()</span></code></a> returns.</p>
<p>In the following description, the quoted form is the format unit; the entry in
(round) parentheses is the Python object type that the format unit will return;
and the entry in [square] brackets is the type of the C value(s) to be passed.</p>
<p>The characters space, tab, colon and comma are ignored in format strings (but
not within format units such as <code class="docutils literal notranslate"><span class="pre">s#</span></code>). This can be used to make long format
strings a tad more readable.</p>
<dl class="simple">
<dt><code class="docutils literal notranslate"><span class="pre">s</span></code> (<a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a> or <code class="docutils literal notranslate"><span class="pre">None</span></code>) [const char *]</dt><dd><p>Convert a null-terminated C string to a Python <a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a> object using <code class="docutils literal notranslate"><span class="pre">'utf-8'</span></code>
encoding. If the C string pointer is <code class="docutils literal notranslate"><span class="pre">NULL</span></code>, <code class="docutils literal notranslate"><span class="pre">None</span></code> is used.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">s#</span></code> (<a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a> or <code class="docutils literal notranslate"><span class="pre">None</span></code>) [const char *, <a class="reference internal" href="intro.html#c.Py_ssize_t" title="Py_ssize_t"><code class="xref c c-type docutils literal notranslate"><span class="pre">Py_ssize_t</span></code></a>]</dt><dd><p>Convert a C string and its length to a Python <a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a> object using <code class="docutils literal notranslate"><span class="pre">'utf-8'</span></code>
encoding. If the C string pointer is <code class="docutils literal notranslate"><span class="pre">NULL</span></code>, the length is ignored and
<code class="docutils literal notranslate"><span class="pre">None</span></code> is returned.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">y</span></code> (<a class="reference internal" href="../library/stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a>) [const char *]</dt><dd><p>This converts a C string to a Python <a class="reference internal" href="../library/stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a> object. If the C
string pointer is <code class="docutils literal notranslate"><span class="pre">NULL</span></code>, <code class="docutils literal notranslate"><span class="pre">None</span></code> is returned.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">y#</span></code> (<a class="reference internal" href="../library/stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a>) [const char *, <a class="reference internal" href="intro.html#c.Py_ssize_t" title="Py_ssize_t"><code class="xref c c-type docutils literal notranslate"><span class="pre">Py_ssize_t</span></code></a>]</dt><dd><p>This converts a C string and its lengths to a Python object. If the C
string pointer is <code class="docutils literal notranslate"><span class="pre">NULL</span></code>, <code class="docutils literal notranslate"><span class="pre">None</span></code> is returned.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">z</span></code> (<a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a> or <code class="docutils literal notranslate"><span class="pre">None</span></code>) [const char *]</dt><dd><p>Same as <code class="docutils literal notranslate"><span class="pre">s</span></code>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">z#</span></code> (<a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a> or <code class="docutils literal notranslate"><span class="pre">None</span></code>) [const char *, <a class="reference internal" href="intro.html#c.Py_ssize_t" title="Py_ssize_t"><code class="xref c c-type docutils literal notranslate"><span class="pre">Py_ssize_t</span></code></a>]</dt><dd><p>Same as <code class="docutils literal notranslate"><span class="pre">s#</span></code>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">u</span></code> (<a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a>) [const wchar_t *]</dt><dd><p>Convert a null-terminated <code class="xref c c-type docutils literal notranslate"><span class="pre">wchar_t</span></code> buffer of Unicode (UTF-16 or UCS-4)
data to a Python Unicode object. If the Unicode buffer pointer is <code class="docutils literal notranslate"><span class="pre">NULL</span></code>,
<code class="docutils literal notranslate"><span class="pre">None</span></code> is returned.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">u#</span></code> (<a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a>) [const wchar_t *, <a class="reference internal" href="intro.html#c.Py_ssize_t" title="Py_ssize_t"><code class="xref c c-type docutils literal notranslate"><span class="pre">Py_ssize_t</span></code></a>]</dt><dd><p>Convert a Unicode (UTF-16 or UCS-4) data buffer and its length to a Python
Unicode object. If the Unicode buffer pointer is <code class="docutils literal notranslate"><span class="pre">NULL</span></code>, the length is ignored
and <code class="docutils literal notranslate"><span class="pre">None</span></code> is returned.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">U</span></code> (<a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a> or <code class="docutils literal notranslate"><span class="pre">None</span></code>) [const char *]</dt><dd><p>Same as <code class="docutils literal notranslate"><span class="pre">s</span></code>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">U#</span></code> (<a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a> or <code class="docutils literal notranslate"><span class="pre">None</span></code>) [const char *, <a class="reference internal" href="intro.html#c.Py_ssize_t" title="Py_ssize_t"><code class="xref c c-type docutils literal notranslate"><span class="pre">Py_ssize_t</span></code></a>]</dt><dd><p>Same as <code class="docutils literal notranslate"><span class="pre">s#</span></code>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">i</span></code> (<a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>) [int]</dt><dd><p>Convert a plain C <span class="c-expr sig sig-inline c"><span class="kt">int</span></span> to a Python integer object.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">b</span></code> (<a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>) [char]</dt><dd><p>Convert a plain C <span class="c-expr sig sig-inline c"><span class="kt">char</span></span> to a Python integer object.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">h</span></code> (<a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>) [short int]</dt><dd><p>Convert a plain C <span class="c-expr sig sig-inline c"><span class="kt">short</span><span class="w"> </span><span class="kt">int</span></span> to a Python integer object.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">l</span></code> (<a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>) [long int]</dt><dd><p>Convert a C <span class="c-expr sig sig-inline c"><span class="kt">long</span><span class="w"> </span><span class="kt">int</span></span> to a Python integer object.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">B</span></code> (<a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>) [unsigned char]</dt><dd><p>Convert a C <span class="c-expr sig sig-inline c"><span class="kt">unsigned</span><span class="w"> </span><span class="kt">char</span></span> to a Python integer object.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">H</span></code> (<a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>) [unsigned short int]</dt><dd><p>Convert a C <span class="c-expr sig sig-inline c"><span class="kt">unsigned</span><span class="w"> </span><span class="kt">short</span><span class="w"> </span><span class="kt">int</span></span> to a Python integer object.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">I</span></code> (<a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>) [unsigned int]</dt><dd><p>Convert a C <span class="c-expr sig sig-inline c"><span class="kt">unsigned</span><span class="w"> </span><span class="kt">int</span></span> to a Python integer object.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">k</span></code> (<a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>) [unsigned long]</dt><dd><p>Convert a C <span class="c-expr sig sig-inline c"><span class="kt">unsigned</span><span class="w"> </span><span class="kt">long</span></span> to a Python integer object.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">L</span></code> (<a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>) [long long]</dt><dd><p>Convert a C <span class="c-expr sig sig-inline c"><span class="kt">long</span><span class="w"> </span><span class="kt">long</span></span> to a Python integer object.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">K</span></code> (<a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>) [unsigned long long]</dt><dd><p>Convert a C <span class="c-expr sig sig-inline c"><span class="kt">unsigned</span><span class="w"> </span><span class="kt">long</span><span class="w"> </span><span class="kt">long</span></span> to a Python integer object.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">n</span></code> (<a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>) [<a class="reference internal" href="intro.html#c.Py_ssize_t" title="Py_ssize_t"><code class="xref c c-type docutils literal notranslate"><span class="pre">Py_ssize_t</span></code></a>]</dt><dd><p>Convert a C <a class="reference internal" href="intro.html#c.Py_ssize_t" title="Py_ssize_t"><code class="xref c c-type docutils literal notranslate"><span class="pre">Py_ssize_t</span></code></a> to a Python integer.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">c</span></code> (<a class="reference internal" href="../library/stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a> of length 1) [char]</dt><dd><p>Convert a C <span class="c-expr sig sig-inline c"><span class="kt">int</span></span> representing a byte to a Python <a class="reference internal" href="../library/stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a> object of
length 1.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">C</span></code> (<a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a> of length 1) [int]</dt><dd><p>Convert a C <span class="c-expr sig sig-inline c"><span class="kt">int</span></span> representing a character to Python <a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a>
object of length 1.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">d</span></code> (<a class="reference internal" href="../library/functions.html#float" title="float"><code class="xref py py-class docutils literal notranslate"><span class="pre">float</span></code></a>) [double]</dt><dd><p>Convert a C <span class="c-expr sig sig-inline c"><span class="kt">double</span></span> to a Python floating-point number.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">f</span></code> (<a class="reference internal" href="../library/functions.html#float" title="float"><code class="xref py py-class docutils literal notranslate"><span class="pre">float</span></code></a>) [float]</dt><dd><p>Convert a C <span class="c-expr sig sig-inline c"><span class="kt">float</span></span> to a Python floating-point number.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">D</span></code> (<a class="reference internal" href="../library/functions.html#complex" title="complex"><code class="xref py py-class docutils literal notranslate"><span class="pre">complex</span></code></a>) [Py_complex *]</dt><dd><p>Convert a C <a class="reference internal" href="complex.html#c.Py_complex" title="Py_complex"><code class="xref c c-type docutils literal notranslate"><span class="pre">Py_complex</span></code></a> structure to a Python complex number.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">O</span></code> (object) [PyObject *]</dt><dd><p>Pass a Python object untouched but create a new
<a class="reference internal" href="../glossary.html#term-strong-reference"><span class="xref std std-term">strong reference</span></a> to it
(i.e. its reference count is incremented by one).
If the object passed in is a <code class="docutils literal notranslate"><span class="pre">NULL</span></code> pointer, it is assumed
that this was caused because the call producing the argument found an error and
set an exception. Therefore, <a class="reference internal" href="#c.Py_BuildValue" title="Py_BuildValue"><code class="xref c c-func docutils literal notranslate"><span class="pre">Py_BuildValue()</span></code></a> will return <code class="docutils literal notranslate"><span class="pre">NULL</span></code> but won’t
raise an exception. If no exception has been raised yet, <a class="reference internal" href="../library/exceptions.html#SystemError" title="SystemError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">SystemError</span></code></a> is
set.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">S</span></code> (object) [PyObject *]</dt><dd><p>Same as <code class="docutils literal notranslate"><span class="pre">O</span></code>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">N</span></code> (object) [PyObject *]</dt><dd><p>Same as <code class="docutils literal notranslate"><span class="pre">O</span></code>, except it doesn’t create a new <a class="reference internal" href="../glossary.html#term-strong-reference"><span class="xref std std-term">strong reference</span></a>.
Useful when the object is created by a call to an object constructor in the
argument list.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">O&</span></code> (object) [<em>converter</em>, <em>anything</em>]</dt><dd><p>Convert <em>anything</em> to a Python object through a <em>converter</em> function. The
function is called with <em>anything</em> (which should be compatible with <span class="c-expr sig sig-inline c"><span class="kt">void</span><span class="p">*</span></span>)
as its argument and should return a “new” Python object, or <code class="docutils literal notranslate"><span class="pre">NULL</span></code> if an
error occurred.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">(items)</span></code> (<a class="reference internal" href="../library/stdtypes.html#tuple" title="tuple"><code class="xref py py-class docutils literal notranslate"><span class="pre">tuple</span></code></a>) [<em>matching-items</em>]</dt><dd><p>Convert a sequence of C values to a Python tuple with the same number of items.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">[items]</span></code> (<a class="reference internal" href="../library/stdtypes.html#list" title="list"><code class="xref py py-class docutils literal notranslate"><span class="pre">list</span></code></a>) [<em>matching-items</em>]</dt><dd><p>Convert a sequence of C values to a Python list with the same number of items.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">{items}</span></code> (<a class="reference internal" href="../library/stdtypes.html#dict" title="dict"><code class="xref py py-class docutils literal notranslate"><span class="pre">dict</span></code></a>) [<em>matching-items</em>]</dt><dd><p>Convert a sequence of C values to a Python dictionary. Each pair of consecutive
C values adds one item to the dictionary, serving as key and value,
respectively.</p>
</dd>
</dl>
<p>If there is an error in the format string, the <a class="reference internal" href="../library/exceptions.html#SystemError" title="SystemError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">SystemError</span></code></a> exception is
set and <code class="docutils literal notranslate"><span class="pre">NULL</span></code> returned.</p>
</dd></dl>
<dl class="c function">
<dt class="sig sig-object c" id="c.Py_VaBuildValue">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="sig-name descname"><span class="n"><span class="pre">Py_VaBuildValue</span></span></span><span class="sig-paren">(</span><span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">format</span></span>, <span class="n"><span class="pre">va_list</span></span><span class="w"> </span><span class="n"><span class="pre">vargs</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.Py_VaBuildValue" title="Link to this definition">¶</a><br /></dt>
<dd><em class="refcount return_new_ref">Return value: New reference.</em><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p>Identical to <a class="reference internal" href="#c.Py_BuildValue" title="Py_BuildValue"><code class="xref c c-func docutils literal notranslate"><span class="pre">Py_BuildValue()</span></code></a>, except that it accepts a va_list
rather than a variable number of arguments.</p>
</dd></dl>
</section>
</section>
<div class="clearer"></div>
</div>
</div>
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<h3><a href="../contents.html">Table of Contents</a></h3>
<ul>
<li><a class="reference internal" href="#">Parsing arguments and building values</a><ul>
<li><a class="reference internal" href="#parsing-arguments">Parsing arguments</a><ul>
<li><a class="reference internal" href="#strings-and-buffers">Strings and buffers</a></li>
<li><a class="reference internal" href="#numbers">Numbers</a></li>
<li><a class="reference internal" href="#other-objects">Other objects</a></li>
<li><a class="reference internal" href="#api-functions">API Functions</a></li>
</ul>
</li>
<li><a class="reference internal" href="#building-values">Building values</a></li>
</ul>
</li>
</ul>
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<h4>Previous topic</h4>
<p class="topless"><a href="marshal.html"
title="previous chapter">Data marshalling support</a></p>
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