<!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta charset="utf-8" /> <title>Slice Objects — Python 3.7.10 documentation</title> <link rel="stylesheet" href="../_static/pydoctheme.css" type="text/css" /> <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> <script type="text/javascript" id="documentation_options" data-url_root="../" src="../_static/documentation_options.js"></script> <script type="text/javascript" src="../_static/jquery.js"></script> <script type="text/javascript" src="../_static/underscore.js"></script> <script type="text/javascript" src="../_static/doctools.js"></script> <script type="text/javascript" src="../_static/language_data.js"></script> <script type="text/javascript" src="../_static/sidebar.js"></script> <link rel="search" type="application/opensearchdescription+xml" title="Search within Python 3.7.10 documentation" href="../_static/opensearch.xml"/> <link rel="author" title="About these documents" href="../about.html" /> <link rel="index" title="Index" href="../genindex.html" /> <link rel="search" title="Search" href="../search.html" /> <link rel="copyright" title="Copyright" href="../copyright.html" /> <link rel="next" title="MemoryView objects" href="memoryview.html" /> <link rel="prev" title="Descriptor Objects" href="descriptor.html" /> <link rel="shortcut icon" type="image/png" href="../_static/py.png" /> <link rel="canonical" href="https://docs.python.org/3/c-api/slice.html" /> <script type="text/javascript" src="../_static/copybutton.js"></script> <style> @media only screen { table.full-width-table { width: 100%; } } </style> </head><body> <div class="related" role="navigation" aria-label="related navigation"> <h3>Navigation</h3> <ul> <li class="right" style="margin-right: 10px"> <a href="../genindex.html" title="General Index" accesskey="I">index</a></li> <li class="right" > <a href="../py-modindex.html" title="Python Module Index" >modules</a> |</li> <li class="right" > <a href="memoryview.html" title="MemoryView objects" accesskey="N">next</a> |</li> <li class="right" > <a href="descriptor.html" title="Descriptor Objects" accesskey="P">previous</a> |</li> <li><img src="../_static/py.png" alt="" style="vertical-align: middle; margin-top: -1px"/></li> <li><a href="https://www.python.org/">Python</a> »</li> <li> <a href="../index.html">3.7.10 Documentation</a> » </li> <li class="nav-item nav-item-1"><a href="index.html" >Python/C API Reference Manual</a> »</li> <li class="nav-item nav-item-2"><a href="concrete.html" accesskey="U">Concrete Objects Layer</a> »</li> <li class="right"> <div class="inline-search" style="display: none" role="search"> <form class="inline-search" action="../search.html" method="get"> <input placeholder="Quick search" type="text" name="q" /> <input type="submit" value="Go" /> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> </div> <script type="text/javascript">$('.inline-search').show(0);</script> | </li> </ul> </div> <div class="document"> <div class="documentwrapper"> <div class="bodywrapper"> <div class="body" role="main"> <div class="section" id="slice-objects"> <span id="id1"></span><h1>Slice Objects<a class="headerlink" href="#slice-objects" title="Permalink to this headline">¶</a></h1> <dl class="var"> <dt id="c.PySlice_Type"> <a class="reference internal" href="type.html#c.PyTypeObject" title="PyTypeObject">PyTypeObject</a> <code class="sig-name descname">PySlice_Type</code><a class="headerlink" href="#c.PySlice_Type" title="Permalink to this definition">¶</a></dt> <dd><p>The type object for slice objects. This is the same as <a class="reference internal" href="../library/functions.html#slice" title="slice"><code class="xref py py-class docutils literal notranslate"><span class="pre">slice</span></code></a> in the Python layer.</p> </dd></dl> <dl class="function"> <dt id="c.PySlice_Check"> int <code class="sig-name descname">PySlice_Check</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *ob</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PySlice_Check" title="Permalink to this definition">¶</a></dt> <dd><p>Return true if <em>ob</em> is a slice object; <em>ob</em> must not be <code class="docutils literal notranslate"><span class="pre">NULL</span></code>.</p> </dd></dl> <dl class="function"> <dt id="c.PySlice_New"> <a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a>* <code class="sig-name descname">PySlice_New</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *start</em>, <a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *stop</em>, <a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *step</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PySlice_New" title="Permalink to this definition">¶</a></dt> <dd><em class="refcount">Return value: New reference.</em><p>Return a new slice object with the given values. The <em>start</em>, <em>stop</em>, and <em>step</em> parameters are used as the values of the slice object attributes of the same names. Any of the values may be <code class="docutils literal notranslate"><span class="pre">NULL</span></code>, in which case the <code class="docutils literal notranslate"><span class="pre">None</span></code> will be used for the corresponding attribute. Return <code class="docutils literal notranslate"><span class="pre">NULL</span></code> if the new object could not be allocated.</p> </dd></dl> <dl class="function"> <dt id="c.PySlice_GetIndices"> int <code class="sig-name descname">PySlice_GetIndices</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *slice</em>, Py_ssize_t<em> length</em>, Py_ssize_t<em> *start</em>, Py_ssize_t<em> *stop</em>, Py_ssize_t<em> *step</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PySlice_GetIndices" title="Permalink to this definition">¶</a></dt> <dd><p>Retrieve the start, stop and step indices from the slice object <em>slice</em>, assuming a sequence of length <em>length</em>. Treats indices greater than <em>length</em> as errors.</p> <p>Returns <code class="docutils literal notranslate"><span class="pre">0</span></code> on success and <code class="docutils literal notranslate"><span class="pre">-1</span></code> on error with no exception set (unless one of the indices was not <a class="reference internal" href="../library/constants.html#None" title="None"><code class="xref py py-const docutils literal notranslate"><span class="pre">None</span></code></a> and failed to be converted to an integer, in which case <code class="docutils literal notranslate"><span class="pre">-1</span></code> is returned with an exception set).</p> <p>You probably do not want to use this function.</p> <div class="versionchanged"> <p><span class="versionmodified changed">Changed in version 3.2: </span>The parameter type for the <em>slice</em> parameter was <code class="docutils literal notranslate"><span class="pre">PySliceObject*</span></code> before.</p> </div> </dd></dl> <dl class="function"> <dt id="c.PySlice_GetIndicesEx"> int <code class="sig-name descname">PySlice_GetIndicesEx</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *slice</em>, Py_ssize_t<em> length</em>, Py_ssize_t<em> *start</em>, Py_ssize_t<em> *stop</em>, Py_ssize_t<em> *step</em>, Py_ssize_t<em> *slicelength</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PySlice_GetIndicesEx" title="Permalink to this definition">¶</a></dt> <dd><p>Usable replacement for <a class="reference internal" href="#c.PySlice_GetIndices" title="PySlice_GetIndices"><code class="xref c c-func docutils literal notranslate"><span class="pre">PySlice_GetIndices()</span></code></a>. Retrieve the start, stop, and step indices from the slice object <em>slice</em> assuming a sequence of length <em>length</em>, and store the length of the slice in <em>slicelength</em>. Out of bounds indices are clipped in a manner consistent with the handling of normal slices.</p> <p>Returns <code class="docutils literal notranslate"><span class="pre">0</span></code> on success and <code class="docutils literal notranslate"><span class="pre">-1</span></code> on error with exception set.</p> <div class="admonition note"> <p class="admonition-title">Note</p> <p>This function is considered not safe for resizable sequences. Its invocation should be replaced by a combination of <a class="reference internal" href="#c.PySlice_Unpack" title="PySlice_Unpack"><code class="xref c c-func docutils literal notranslate"><span class="pre">PySlice_Unpack()</span></code></a> and <a class="reference internal" href="#c.PySlice_AdjustIndices" title="PySlice_AdjustIndices"><code class="xref c c-func docutils literal notranslate"><span class="pre">PySlice_AdjustIndices()</span></code></a> where</p> <div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="k">if</span> <span class="p">(</span><span class="n">PySlice_GetIndicesEx</span><span class="p">(</span><span class="n">slice</span><span class="p">,</span> <span class="n">length</span><span class="p">,</span> <span class="o">&</span><span class="n">start</span><span class="p">,</span> <span class="o">&</span><span class="n">stop</span><span class="p">,</span> <span class="o">&</span><span class="n">step</span><span class="p">,</span> <span class="o">&</span><span class="n">slicelength</span><span class="p">)</span> <span class="o"><</span> <span class="mi">0</span><span class="p">)</span> <span class="p">{</span> <span class="c1">// return error</span> <span class="p">}</span> </pre></div> </div> <p>is replaced by</p> <div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="k">if</span> <span class="p">(</span><span class="n">PySlice_Unpack</span><span class="p">(</span><span class="n">slice</span><span class="p">,</span> <span class="o">&</span><span class="n">start</span><span class="p">,</span> <span class="o">&</span><span class="n">stop</span><span class="p">,</span> <span class="o">&</span><span class="n">step</span><span class="p">)</span> <span class="o"><</span> <span class="mi">0</span><span class="p">)</span> <span class="p">{</span> <span class="c1">// return error</span> <span class="p">}</span> <span class="n">slicelength</span> <span class="o">=</span> <span class="n">PySlice_AdjustIndices</span><span class="p">(</span><span class="n">length</span><span class="p">,</span> <span class="o">&</span><span class="n">start</span><span class="p">,</span> <span class="o">&</span><span class="n">stop</span><span class="p">,</span> <span class="n">step</span><span class="p">);</span> </pre></div> </div> </div> <div class="versionchanged"> <p><span class="versionmodified changed">Changed in version 3.2: </span>The parameter type for the <em>slice</em> parameter was <code class="docutils literal notranslate"><span class="pre">PySliceObject*</span></code> before.</p> </div> <div class="versionchanged"> <p><span class="versionmodified changed">Changed in version 3.6.1: </span>If <code class="docutils literal notranslate"><span class="pre">Py_LIMITED_API</span></code> is not set or set to the value between <code class="docutils literal notranslate"><span class="pre">0x03050400</span></code> and <code class="docutils literal notranslate"><span class="pre">0x03060000</span></code> (not including) or <code class="docutils literal notranslate"><span class="pre">0x03060100</span></code> or higher <code class="xref c c-func docutils literal notranslate"><span class="pre">PySlice_GetIndicesEx()</span></code> is implemented as a macro using <code class="xref c c-func docutils literal notranslate"><span class="pre">PySlice_Unpack()</span></code> and <code class="xref c c-func docutils literal notranslate"><span class="pre">PySlice_AdjustIndices()</span></code>. Arguments <em>start</em>, <em>stop</em> and <em>step</em> are evaluated more than once.</p> </div> <div class="deprecated"> <p><span class="versionmodified deprecated">Deprecated since version 3.6.1: </span>If <code class="docutils literal notranslate"><span class="pre">Py_LIMITED_API</span></code> is set to the value less than <code class="docutils literal notranslate"><span class="pre">0x03050400</span></code> or between <code class="docutils literal notranslate"><span class="pre">0x03060000</span></code> and <code class="docutils literal notranslate"><span class="pre">0x03060100</span></code> (not including) <code class="xref c c-func docutils literal notranslate"><span class="pre">PySlice_GetIndicesEx()</span></code> is a deprecated function.</p> </div> </dd></dl> <dl class="function"> <dt id="c.PySlice_Unpack"> int <code class="sig-name descname">PySlice_Unpack</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *slice</em>, Py_ssize_t<em> *start</em>, Py_ssize_t<em> *stop</em>, Py_ssize_t<em> *step</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PySlice_Unpack" title="Permalink to this definition">¶</a></dt> <dd><p>Extract the start, stop and step data members from a slice object as C integers. Silently reduce values larger than <code class="docutils literal notranslate"><span class="pre">PY_SSIZE_T_MAX</span></code> to <code class="docutils literal notranslate"><span class="pre">PY_SSIZE_T_MAX</span></code>, silently boost the start and stop values less than <code class="docutils literal notranslate"><span class="pre">PY_SSIZE_T_MIN</span></code> to <code class="docutils literal notranslate"><span class="pre">PY_SSIZE_T_MIN</span></code>, and silently boost the step values less than <code class="docutils literal notranslate"><span class="pre">-PY_SSIZE_T_MAX</span></code> to <code class="docutils literal notranslate"><span class="pre">-PY_SSIZE_T_MAX</span></code>.</p> <p>Return <code class="docutils literal notranslate"><span class="pre">-1</span></code> on error, <code class="docutils literal notranslate"><span class="pre">0</span></code> on success.</p> <div class="versionadded"> <p><span class="versionmodified added">New in version 3.6.1.</span></p> </div> </dd></dl> <dl class="function"> <dt id="c.PySlice_AdjustIndices"> Py_ssize_t <code class="sig-name descname">PySlice_AdjustIndices</code><span class="sig-paren">(</span>Py_ssize_t<em> length</em>, Py_ssize_t<em> *start</em>, Py_ssize_t<em> *stop</em>, Py_ssize_t<em> step</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PySlice_AdjustIndices" title="Permalink to this definition">¶</a></dt> <dd><p>Adjust start/end slice indices assuming a sequence of the specified length. Out of bounds indices are clipped in a manner consistent with the handling of normal slices.</p> <p>Return the length of the slice. Always successful. Doesn’t call Python code.</p> <div class="versionadded"> <p><span class="versionmodified added">New in version 3.6.1.</span></p> </div> </dd></dl> </div> <div class="section" id="ellipsis-object"> <h1>Ellipsis Object<a class="headerlink" href="#ellipsis-object" title="Permalink to this headline">¶</a></h1> <dl class="var"> <dt id="c.Py_Ellipsis"> <a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a> *<code class="sig-name descname">Py_Ellipsis</code><a class="headerlink" href="#c.Py_Ellipsis" title="Permalink to this definition">¶</a></dt> <dd><p>The Python <code class="docutils literal notranslate"><span class="pre">Ellipsis</span></code> object. This object has no methods. It needs to be treated just like any other object with respect to reference counts. Like <a class="reference internal" href="none.html#c.Py_None" title="Py_None"><code class="xref c c-data docutils literal notranslate"><span class="pre">Py_None</span></code></a> it is a singleton object.</p> </dd></dl> </div> </div> </div> </div> <div class="sphinxsidebar" role="navigation" aria-label="main navigation"> <div class="sphinxsidebarwrapper"> <h3><a href="../contents.html">Table of Contents</a></h3> <ul> <li><a class="reference internal" href="#">Slice Objects</a></li> <li><a class="reference internal" href="#ellipsis-object">Ellipsis Object</a></li> </ul> <h4>Previous topic</h4> <p class="topless"><a href="descriptor.html" title="previous chapter">Descriptor Objects</a></p> <h4>Next topic</h4> <p class="topless"><a href="memoryview.html" title="next chapter">MemoryView objects</a></p> <div role="note" aria-label="source link"> <h3>This Page</h3> <ul class="this-page-menu"> <li><a href="../bugs.html">Report a Bug</a></li> <li> <a href="https://github.com/python/cpython/blob/3.7/Doc/c-api/slice.rst" rel="nofollow">Show Source </a> </li> </ul> </div> </div> </div> <div class="clearer"></div> </div> <div class="related" role="navigation" aria-label="related navigation"> <h3>Navigation</h3> <ul> <li class="right" style="margin-right: 10px"> <a href="../genindex.html" title="General Index" >index</a></li> <li class="right" > <a href="../py-modindex.html" title="Python Module Index" >modules</a> |</li> <li class="right" > <a href="memoryview.html" title="MemoryView objects" >next</a> |</li> <li class="right" > <a href="descriptor.html" title="Descriptor Objects" >previous</a> |</li> <li><img src="../_static/py.png" alt="" style="vertical-align: middle; margin-top: -1px"/></li> <li><a href="https://www.python.org/">Python</a> »</li> <li> <a href="../index.html">3.7.10 Documentation</a> » </li> <li class="nav-item nav-item-1"><a href="index.html" >Python/C API Reference Manual</a> »</li> <li class="nav-item nav-item-2"><a href="concrete.html" >Concrete Objects Layer</a> »</li> <li class="right"> <div class="inline-search" style="display: none" role="search"> <form class="inline-search" action="../search.html" method="get"> <input placeholder="Quick search" type="text" name="q" /> <input type="submit" value="Go" /> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> </div> <script type="text/javascript">$('.inline-search').show(0);</script> | </li> </ul> </div> <div class="footer"> © <a href="../copyright.html">Copyright</a> 2001-2021, Python Software Foundation. <br /> The Python Software Foundation is a non-profit corporation. <a href="https://www.python.org/psf/donations/">Please donate.</a> <br /> Last updated on Feb 26, 2021. <a href="../bugs.html">Found a bug</a>? <br /> Created using <a href="http://sphinx.pocoo.org/">Sphinx</a> 2.3.1. </div> </body> </html>