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198 <div class="section" id="generating-hash-values-directly">
199 <h1>Generating hash values directly<a class="headerlink" href="#generating-hash-values-directly" title="Permalink to this headline"></a></h1>
200 <p>Hash a key value</p>
201 <div class="section" id="synopsis">
202 <h2>SYNOPSIS<a class="headerlink" href="#synopsis" title="Permalink to this headline"></a></h2>
203 <dl class="docutils">
204 <dt>#include &lt;libmemcached/memcached.h&gt;</dt>
205 <dd>Compile and link with -lmemcachedutil -lmemcached</dd>
206 </dl>
207 <dl class="function">
208 <dt id="_CPPv429memcached_generate_hash_valuePKc6size_t16memcached_hash_t">
209 <span id="_CPPv329memcached_generate_hash_valuePKc6size_t16memcached_hash_t"></span><span id="_CPPv229memcached_generate_hash_valuePKc6size_t16memcached_hash_t"></span><span id="memcached_generate_hash_value__cCP.s.memcached_hash_t"></span>uint32_t <code class="descname">memcached_generate_hash_value</code><span class="sig-paren">(</span><em class="property">const</em> char *<em>key</em>, size_t <em>key_length</em>, <a class="reference internal" href="#_CPPv416memcached_hash_t" title="memcached_hash_t">memcached_hash_t</a> <em>hash_algorithm</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv429memcached_generate_hash_valuePKc6size_t16memcached_hash_t" title="Permalink to this definition"></a><br /></dt>
210 <dd><table class="docutils field-list" frame="void" rules="none">
211 <col class="field-name" />
212 <col class="field-body" />
213 <tbody valign="top">
214 <tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
215 <li><strong>key</strong> -- the key to generate a hash of</li>
216 <li><strong>key_length</strong> -- the length of the <a class="reference internal" href="#_CPPv429memcached_generate_hash_valuePKc6size_t16memcached_hash_t" title="memcached_generate_hash_value::key"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">key</span></code></a> without any terminating zero</li>
217 <li><strong>hash_algorithm</strong> -- <a class="reference internal" href="#_CPPv416memcached_hash_t" title="memcached_hash_t"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">memcached_hash_t</span></code></a>, the algorithm to use</li>
218 </ul>
219 </td>
220 </tr>
221 <tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first last">a 32 bit hash value</p>
222 </td>
223 </tr>
224 </tbody>
225 </table>
226 </dd></dl>
227
228 <dl class="function">
229 <dt id="_CPPv423memcached_generate_hashP12memcached_stPKc6size_t">
230 <span id="_CPPv323memcached_generate_hashP12memcached_stPKc6size_t"></span><span id="_CPPv223memcached_generate_hashP12memcached_stPKc6size_t"></span><span id="memcached_generate_hash__memcached_stP.cCP.s"></span>uint32_t <code class="descname">memcached_generate_hash</code><span class="sig-paren">(</span><a class="reference internal" href="memcached_create.html#_CPPv412memcached_st" title="memcached_st">memcached_st</a> *<em>ptr</em>, <em class="property">const</em> char *<em>key</em>, size_t <em>key_length</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv423memcached_generate_hashP12memcached_stPKc6size_t" title="Permalink to this definition"></a><br /></dt>
231 <dd><table class="docutils field-list" frame="void" rules="none">
232 <col class="field-name" />
233 <col class="field-body" />
234 <tbody valign="top">
235 <tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
236 <li><strong>ptr</strong> -- pointer to an initialized <a class="reference internal" href="memcached_create.html#_CPPv412memcached_st" title="memcached_st"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">memcached_st</span></code></a> struct</li>
237 <li><strong>key</strong> -- the key to generate a hash of</li>
238 <li><strong>key_length</strong> -- the length of the <a class="reference internal" href="#_CPPv423memcached_generate_hashP12memcached_stPKc6size_t" title="memcached_generate_hash::key"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">key</span></code></a> without any terminating zero</li>
239 </ul>
240 </td>
241 </tr>
242 <tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first last">a 32 bit hash value</p>
243 </td>
244 </tr>
245 </tbody>
246 </table>
247 </dd></dl>
248
249 <dl class="type">
250 <dt id="c.memcached_hash_t">
251 enum <a class="reference internal" href="#c.memcached_hash_t" title="memcached_hash_t">memcached_hash_t</a> <code class="descname">memcached_hash_t</code><a class="headerlink" href="#c.memcached_hash_t" title="Permalink to this definition"></a></dt>
252 <dd></dd></dl>
253
254 <dl class="enum">
255 <dt id="_CPPv416memcached_hash_t">
256 <span id="_CPPv316memcached_hash_t"></span><span id="_CPPv216memcached_hash_t"></span><em class="property">enum </em><code class="descname">memcached_hash_t</code><a class="headerlink" href="#_CPPv416memcached_hash_t" title="Permalink to this definition"></a><br /></dt>
257 <dd><dl class="enumerator">
258 <dt id="_CPPv4N16memcached_hash_t22MEMCACHED_HASH_DEFAULTE">
259 <span id="_CPPv3N16memcached_hash_t22MEMCACHED_HASH_DEFAULTE"></span><span id="_CPPv2N16memcached_hash_t22MEMCACHED_HASH_DEFAULTE"></span><em class="property">enumerator </em><code class="descname">MEMCACHED_HASH_DEFAULT</code><a class="headerlink" href="#_CPPv4N16memcached_hash_t22MEMCACHED_HASH_DEFAULTE" title="Permalink to this definition"></a><br /></dt>
260 <dd></dd></dl>
261
262 <dl class="enumerator">
263 <dt id="_CPPv4N16memcached_hash_t18MEMCACHED_HASH_MD5E">
264 <span id="_CPPv3N16memcached_hash_t18MEMCACHED_HASH_MD5E"></span><span id="_CPPv2N16memcached_hash_t18MEMCACHED_HASH_MD5E"></span><em class="property">enumerator </em><code class="descname">MEMCACHED_HASH_MD5</code><a class="headerlink" href="#_CPPv4N16memcached_hash_t18MEMCACHED_HASH_MD5E" title="Permalink to this definition"></a><br /></dt>
265 <dd></dd></dl>
266
267 <dl class="enumerator">
268 <dt id="_CPPv4N16memcached_hash_t18MEMCACHED_HASH_CRCE">
269 <span id="_CPPv3N16memcached_hash_t18MEMCACHED_HASH_CRCE"></span><span id="_CPPv2N16memcached_hash_t18MEMCACHED_HASH_CRCE"></span><em class="property">enumerator </em><code class="descname">MEMCACHED_HASH_CRC</code><a class="headerlink" href="#_CPPv4N16memcached_hash_t18MEMCACHED_HASH_CRCE" title="Permalink to this definition"></a><br /></dt>
270 <dd></dd></dl>
271
272 <dl class="enumerator">
273 <dt id="_CPPv4N16memcached_hash_t22MEMCACHED_HASH_FNV1_64E">
274 <span id="_CPPv3N16memcached_hash_t22MEMCACHED_HASH_FNV1_64E"></span><span id="_CPPv2N16memcached_hash_t22MEMCACHED_HASH_FNV1_64E"></span><em class="property">enumerator </em><code class="descname">MEMCACHED_HASH_FNV1_64</code><a class="headerlink" href="#_CPPv4N16memcached_hash_t22MEMCACHED_HASH_FNV1_64E" title="Permalink to this definition"></a><br /></dt>
275 <dd></dd></dl>
276
277 <dl class="enumerator">
278 <dt id="_CPPv4N16memcached_hash_t23MEMCACHED_HASH_FNV1A_64E">
279 <span id="_CPPv3N16memcached_hash_t23MEMCACHED_HASH_FNV1A_64E"></span><span id="_CPPv2N16memcached_hash_t23MEMCACHED_HASH_FNV1A_64E"></span><em class="property">enumerator </em><code class="descname">MEMCACHED_HASH_FNV1A_64</code><a class="headerlink" href="#_CPPv4N16memcached_hash_t23MEMCACHED_HASH_FNV1A_64E" title="Permalink to this definition"></a><br /></dt>
280 <dd></dd></dl>
281
282 <dl class="enumerator">
283 <dt id="_CPPv4N16memcached_hash_t22MEMCACHED_HASH_FNV1_32E">
284 <span id="_CPPv3N16memcached_hash_t22MEMCACHED_HASH_FNV1_32E"></span><span id="_CPPv2N16memcached_hash_t22MEMCACHED_HASH_FNV1_32E"></span><em class="property">enumerator </em><code class="descname">MEMCACHED_HASH_FNV1_32</code><a class="headerlink" href="#_CPPv4N16memcached_hash_t22MEMCACHED_HASH_FNV1_32E" title="Permalink to this definition"></a><br /></dt>
285 <dd></dd></dl>
286
287 <dl class="enumerator">
288 <dt id="_CPPv4N16memcached_hash_t23MEMCACHED_HASH_FNV1A_32E">
289 <span id="_CPPv3N16memcached_hash_t23MEMCACHED_HASH_FNV1A_32E"></span><span id="_CPPv2N16memcached_hash_t23MEMCACHED_HASH_FNV1A_32E"></span><em class="property">enumerator </em><code class="descname">MEMCACHED_HASH_FNV1A_32</code><a class="headerlink" href="#_CPPv4N16memcached_hash_t23MEMCACHED_HASH_FNV1A_32E" title="Permalink to this definition"></a><br /></dt>
290 <dd></dd></dl>
291
292 <dl class="enumerator">
293 <dt id="_CPPv4N16memcached_hash_t20MEMCACHED_HASH_HSIEHE">
294 <span id="_CPPv3N16memcached_hash_t20MEMCACHED_HASH_HSIEHE"></span><span id="_CPPv2N16memcached_hash_t20MEMCACHED_HASH_HSIEHE"></span><em class="property">enumerator </em><code class="descname">MEMCACHED_HASH_HSIEH</code><a class="headerlink" href="#_CPPv4N16memcached_hash_t20MEMCACHED_HASH_HSIEHE" title="Permalink to this definition"></a><br /></dt>
295 <dd></dd></dl>
296
297 <dl class="enumerator">
298 <dt id="_CPPv4N16memcached_hash_t21MEMCACHED_HASH_MURMURE">
299 <span id="_CPPv3N16memcached_hash_t21MEMCACHED_HASH_MURMURE"></span><span id="_CPPv2N16memcached_hash_t21MEMCACHED_HASH_MURMURE"></span><em class="property">enumerator </em><code class="descname">MEMCACHED_HASH_MURMUR</code><a class="headerlink" href="#_CPPv4N16memcached_hash_t21MEMCACHED_HASH_MURMURE" title="Permalink to this definition"></a><br /></dt>
300 <dd></dd></dl>
301
302 <dl class="enumerator">
303 <dt id="_CPPv4N16memcached_hash_t22MEMCACHED_HASH_JENKINSE">
304 <span id="_CPPv3N16memcached_hash_t22MEMCACHED_HASH_JENKINSE"></span><span id="_CPPv2N16memcached_hash_t22MEMCACHED_HASH_JENKINSE"></span><em class="property">enumerator </em><code class="descname">MEMCACHED_HASH_JENKINS</code><a class="headerlink" href="#_CPPv4N16memcached_hash_t22MEMCACHED_HASH_JENKINSE" title="Permalink to this definition"></a><br /></dt>
305 <dd></dd></dl>
306
307 <dl class="enumerator">
308 <dt id="_CPPv4N16memcached_hash_t22MEMCACHED_HASH_MURMUR3E">
309 <span id="_CPPv3N16memcached_hash_t22MEMCACHED_HASH_MURMUR3E"></span><span id="_CPPv2N16memcached_hash_t22MEMCACHED_HASH_MURMUR3E"></span><em class="property">enumerator </em><code class="descname">MEMCACHED_HASH_MURMUR3</code><a class="headerlink" href="#_CPPv4N16memcached_hash_t22MEMCACHED_HASH_MURMUR3E" title="Permalink to this definition"></a><br /></dt>
310 <dd></dd></dl>
311
312 <dl class="enumerator">
313 <dt id="_CPPv4N16memcached_hash_t21MEMCACHED_HASH_CUSTOME">
314 <span id="_CPPv3N16memcached_hash_t21MEMCACHED_HASH_CUSTOME"></span><span id="_CPPv2N16memcached_hash_t21MEMCACHED_HASH_CUSTOME"></span><em class="property">enumerator </em><code class="descname">MEMCACHED_HASH_CUSTOM</code><a class="headerlink" href="#_CPPv4N16memcached_hash_t21MEMCACHED_HASH_CUSTOME" title="Permalink to this definition"></a><br /></dt>
315 <dd></dd></dl>
316
317 </dd></dl>
318
319 </div>
320 <div class="section" id="description">
321 <h2>DESCRIPTION<a class="headerlink" href="#description" title="Permalink to this headline"></a></h2>
322 <p><a class="reference internal" href="#_CPPv429memcached_generate_hash_valuePKc6size_t16memcached_hash_t" title="memcached_generate_hash_value"><code class="xref cpp cpp-func docutils literal notranslate"><span class="pre">memcached_generate_hash_value()</span></code></a> allows you to hash a key using one of
323 the hash functions defined in the library. This method is provided for
324 the convenience of higher-level language bindings and is not necessary
325 for normal memcache operations.</p>
326 <p>Support for <a class="reference internal" href="#_CPPv4N16memcached_hash_t20MEMCACHED_HASH_HSIEHE" title="MEMCACHED_HASH_HSIEH"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">MEMCACHED_HASH_HSIEH</span></code></a> is a compile time option that is
327 disabled by default. To enable tests for this hashing algorithm,
328 configure and build libmemcached with the Hsieh hash enabled.</p>
329 <p><a class="reference internal" href="#_CPPv423memcached_generate_hashP12memcached_stPKc6size_t" title="memcached_generate_hash"><code class="xref cpp cpp-func docutils literal notranslate"><span class="pre">memcached_generate_hash()</span></code></a> takes a <a class="reference internal" href="memcached_create.html#_CPPv412memcached_st" title="memcached_st"><code class="xref cpp cpp-type docutils literal notranslate"><span class="pre">memcached_st</span></code></a> structure
330 and produces the hash value that would have been generated based on the
331 defaults of <a class="reference internal" href="memcached_create.html#_CPPv412memcached_st" title="memcached_st"><code class="xref cpp cpp-type docutils literal notranslate"><span class="pre">memcached_st</span></code></a>.</p>
332 <p>As of version 0.36 all hash methods have been placed into the library
333 libhashkit(3) which is linked with libmemcached(3). For more information please see its documentation.</p>
334 </div>
335 <div class="section" id="return-value">
336 <h2>RETURN VALUE<a class="headerlink" href="#return-value" title="Permalink to this headline"></a></h2>
337 <p>A 32-bit integer which is the result of hashing the given key.
338 For 64-bit hash algorithms, only the least-significant 32 bits are
339 returned.</p>
340 </div>
341 <div class="section" id="see-also">
342 <h2>SEE ALSO<a class="headerlink" href="#see-also" title="Permalink to this headline"></a></h2>
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