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<section id="pyhash-api">
<h1>PyHash API<a class="headerlink" href="#pyhash-api" title="Link to this heading">¶</a></h1>
<p>See also the <a class="reference internal" href="typeobj.html#c.PyTypeObject.tp_hash" title="PyTypeObject.tp_hash"><code class="xref c c-member docutils literal notranslate"><span class="pre">PyTypeObject.tp_hash</span></code></a> member and <a class="reference internal" href="../library/stdtypes.html#numeric-hash"><span class="std std-ref">Hashing of numeric types</span></a>.</p>
<dl class="c type">
<dt class="sig sig-object c" id="c.Py_hash_t">
<span class="k"><span class="pre">type</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">Py_hash_t</span></span></span><a class="headerlink" href="#c.Py_hash_t" title="Link to this definition">¶</a><br /></dt>
<dd><p>Hash value type: signed integer.</p>
<div class="versionadded">
<p><span class="versionmodified added">Added in version 3.2.</span></p>
</div>
</dd></dl>
<dl class="c type">
<dt class="sig sig-object c" id="c.Py_uhash_t">
<span class="k"><span class="pre">type</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">Py_uhash_t</span></span></span><a class="headerlink" href="#c.Py_uhash_t" title="Link to this definition">¶</a><br /></dt>
<dd><p>Hash value type: unsigned integer.</p>
<div class="versionadded">
<p><span class="versionmodified added">Added in version 3.2.</span></p>
</div>
</dd></dl>
<dl class="c macro">
<dt class="sig sig-object c" id="c.PyHASH_MODULUS">
<span class="sig-name descname"><span class="n"><span class="pre">PyHASH_MODULUS</span></span></span><a class="headerlink" href="#c.PyHASH_MODULUS" title="Link to this definition">¶</a><br /></dt>
<dd><p>The <a class="reference external" href="https://en.wikipedia.org/wiki/Mersenne_prime">Mersenne prime</a> <code class="docutils literal notranslate"><span class="pre">P</span> <span class="pre">=</span> <span class="pre">2**n</span> <span class="pre">-1</span></code>, used for numeric hash scheme.</p>
<div class="versionadded">
<p><span class="versionmodified added">Added in version 3.13.</span></p>
</div>
</dd></dl>
<dl class="c macro">
<dt class="sig sig-object c" id="c.PyHASH_BITS">
<span class="sig-name descname"><span class="n"><span class="pre">PyHASH_BITS</span></span></span><a class="headerlink" href="#c.PyHASH_BITS" title="Link to this definition">¶</a><br /></dt>
<dd><p>The exponent <code class="docutils literal notranslate"><span class="pre">n</span></code> of <code class="docutils literal notranslate"><span class="pre">P</span></code> in <a class="reference internal" href="#c.PyHASH_MODULUS" title="PyHASH_MODULUS"><code class="xref c c-macro docutils literal notranslate"><span class="pre">PyHASH_MODULUS</span></code></a>.</p>
<div class="versionadded">
<p><span class="versionmodified added">Added in version 3.13.</span></p>
</div>
</dd></dl>
<dl class="c macro">
<dt class="sig sig-object c" id="c.PyHASH_MULTIPLIER">
<span class="sig-name descname"><span class="n"><span class="pre">PyHASH_MULTIPLIER</span></span></span><a class="headerlink" href="#c.PyHASH_MULTIPLIER" title="Link to this definition">¶</a><br /></dt>
<dd><p>Prime multiplier used in string and various other hashes.</p>
<div class="versionadded">
<p><span class="versionmodified added">Added in version 3.13.</span></p>
</div>
</dd></dl>
<dl class="c macro">
<dt class="sig sig-object c" id="c.PyHASH_INF">
<span class="sig-name descname"><span class="n"><span class="pre">PyHASH_INF</span></span></span><a class="headerlink" href="#c.PyHASH_INF" title="Link to this definition">¶</a><br /></dt>
<dd><p>The hash value returned for a positive infinity.</p>
<div class="versionadded">
<p><span class="versionmodified added">Added in version 3.13.</span></p>
</div>
</dd></dl>
<dl class="c macro">
<dt class="sig sig-object c" id="c.PyHASH_IMAG">
<span class="sig-name descname"><span class="n"><span class="pre">PyHASH_IMAG</span></span></span><a class="headerlink" href="#c.PyHASH_IMAG" title="Link to this definition">¶</a><br /></dt>
<dd><p>The multiplier used for the imaginary part of a complex number.</p>
<div class="versionadded">
<p><span class="versionmodified added">Added in version 3.13.</span></p>
</div>
</dd></dl>
<dl class="c type">
<dt class="sig sig-object c" id="c.PyHash_FuncDef">
<span class="k"><span class="pre">type</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyHash_FuncDef</span></span></span><a class="headerlink" href="#c.PyHash_FuncDef" title="Link to this definition">¶</a><br /></dt>
<dd><p>Hash function definition used by <a class="reference internal" href="#c.PyHash_GetFuncDef" title="PyHash_GetFuncDef"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyHash_GetFuncDef()</span></code></a>.</p>
<dl class="c member">
<dt class="sig sig-object c" id="c.PyHash_FuncDef.name">
<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="sig-name descname"><span class="n"><span class="pre">name</span></span></span><a class="headerlink" href="#c.PyHash_FuncDef.name" title="Link to this definition">¶</a><br /></dt>
<dd><p>Hash function name (UTF-8 encoded string).</p>
</dd></dl>
<dl class="c member">
<dt class="sig sig-object c" id="c.PyHash_FuncDef.hash_bits">
<span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">hash_bits</span></span></span><a class="headerlink" href="#c.PyHash_FuncDef.hash_bits" title="Link to this definition">¶</a><br /></dt>
<dd><p>Internal size of the hash value in bits.</p>
</dd></dl>
<dl class="c member">
<dt class="sig sig-object c" id="c.PyHash_FuncDef.seed_bits">
<span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">seed_bits</span></span></span><a class="headerlink" href="#c.PyHash_FuncDef.seed_bits" title="Link to this definition">¶</a><br /></dt>
<dd><p>Size of seed input in bits.</p>
</dd></dl>
<div class="versionadded">
<p><span class="versionmodified added">Added in version 3.4.</span></p>
</div>
</dd></dl>
<dl class="c function">
<dt class="sig sig-object c" id="c.PyHash_GetFuncDef">
<a class="reference internal" href="#c.PyHash_FuncDef" title="PyHash_FuncDef"><span class="n"><span class="pre">PyHash_FuncDef</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">PyHash_GetFuncDef</span></span></span><span class="sig-paren">(</span><span class="kt"><span class="pre">void</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyHash_GetFuncDef" title="Link to this definition">¶</a><br /></dt>
<dd><p>Get the hash function definition.</p>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p><span class="target" id="index-0"></span><a class="pep reference external" href="https://peps.python.org/pep-0456/"><strong>PEP 456</strong></a> “Secure and interchangeable hash algorithm”.</p>
</div>
<div class="versionadded">
<p><span class="versionmodified added">Added in version 3.4.</span></p>
</div>
</dd></dl>
<dl class="c function">
<dt class="sig sig-object c" id="c.Py_HashPointer">
<a class="reference internal" href="#c.Py_hash_t" title="Py_hash_t"><span class="n"><span class="pre">Py_hash_t</span></span></a><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">Py_HashPointer</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">void</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">ptr</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.Py_HashPointer" title="Link to this definition">¶</a><br /></dt>
<dd><p>Hash a pointer value: process the pointer value as an integer (cast it to
<code class="docutils literal notranslate"><span class="pre">uintptr_t</span></code> internally). The pointer is not dereferenced.</p>
<p>The function cannot fail: it cannot return <code class="docutils literal notranslate"><span class="pre">-1</span></code>.</p>
<div class="versionadded">
<p><span class="versionmodified added">Added in version 3.13.</span></p>
</div>
</dd></dl>
<dl class="c function">
<dt class="sig sig-object c" id="c.PyObject_GenericHash">
<a class="reference internal" href="#c.Py_hash_t" title="Py_hash_t"><span class="n"><span class="pre">Py_hash_t</span></span></a><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyObject_GenericHash</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">obj</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyObject_GenericHash" title="Link to this definition">¶</a><br /></dt>
<dd><p>Generic hashing function that is meant to be put into a type
object’s <code class="docutils literal notranslate"><span class="pre">tp_hash</span></code> slot.
Its result only depends on the object’s identity.</p>
<div class="impl-detail compound">
<p><strong>CPython implementation detail:</strong> In CPython, it is equivalent to <a class="reference internal" href="#c.Py_HashPointer" title="Py_HashPointer"><code class="xref c c-func docutils literal notranslate"><span class="pre">Py_HashPointer()</span></code></a>.</p>
</div>
<div class="versionadded">
<p><span class="versionmodified added">Added in version 3.13.</span></p>
</div>
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