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201 <div class="section" id="generating-hash-values-directly">
202 <h1>Generating hash values directly<a class="headerlink" href="#generating-hash-values-directly" title="Permalink to this headline"></a></h1>
203 <p>Hash a key value</p>
204 <div class="section" id="synopsis">
205 <h2>SYNOPSIS<a class="headerlink" href="#synopsis" title="Permalink to this headline"></a></h2>
206 <dl class="simple">
207 <dt>#include &lt;libmemcached/memcached.h&gt;</dt><dd><p>Compile and link with -lmemcachedutil -lmemcached</p>
208 </dd>
209 </dl>
210 <dl class="cpp function">
211 <dt id="_CPPv429memcached_generate_hash_valuePKc6size_t16memcached_hash_t">
212 <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="sig-name 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>
213 <dd><dl class="field-list simple">
214 <dt class="field-odd">Parameters</dt>
215 <dd class="field-odd"><ul class="simple">
216 <li><p><strong>key</strong> -- the key to generate a hash of</p></li>
217 <li><p><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</p></li>
218 <li><p><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</p></li>
219 </ul>
220 </dd>
221 <dt class="field-even">Returns</dt>
222 <dd class="field-even"><p>a 32 bit hash value</p>
223 </dd>
224 </dl>
225 </dd></dl>
226
227 <dl class="cpp function">
228 <dt id="_CPPv423memcached_generate_hashP12memcached_stPKc6size_t">
229 <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="sig-name 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>
230 <dd><dl class="field-list simple">
231 <dt class="field-odd">Parameters</dt>
232 <dd class="field-odd"><ul class="simple">
233 <li><p><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</p></li>
234 <li><p><strong>key</strong> -- the key to generate a hash of</p></li>
235 <li><p><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</p></li>
236 </ul>
237 </dd>
238 <dt class="field-even">Returns</dt>
239 <dd class="field-even"><p>a 32 bit hash value</p>
240 </dd>
241 </dl>
242 </dd></dl>
243
244 <dl class="c type">
245 <dt id="c.memcached_hash_t">
246 <em class="property">typedef </em><em class="property">enum</em> <a class="reference internal" href="#c.memcached_hash_t" title="memcached_hash_t">memcached_hash_t</a> <code class="sig-name descname">memcached_hash_t</code><a class="headerlink" href="#c.memcached_hash_t" title="Permalink to this definition"></a><br /></dt>
247 <dd></dd></dl>
248
249 <dl class="cpp enum">
250 <dt id="_CPPv416memcached_hash_t">
251 <span id="_CPPv316memcached_hash_t"></span><span id="_CPPv216memcached_hash_t"></span><em class="property">enum </em><code class="sig-name descname">memcached_hash_t</code><a class="headerlink" href="#_CPPv416memcached_hash_t" title="Permalink to this definition"></a><br /></dt>
252 <dd><dl class="cpp enumerator">
253 <dt id="_CPPv4N16memcached_hash_t22MEMCACHED_HASH_DEFAULTE">
254 <span id="_CPPv3N16memcached_hash_t22MEMCACHED_HASH_DEFAULTE"></span><span id="_CPPv2N16memcached_hash_t22MEMCACHED_HASH_DEFAULTE"></span><em class="property">enumerator </em><code class="sig-name descname">MEMCACHED_HASH_DEFAULT</code><a class="headerlink" href="#_CPPv4N16memcached_hash_t22MEMCACHED_HASH_DEFAULTE" title="Permalink to this definition"></a><br /></dt>
255 <dd></dd></dl>
256
257 <dl class="cpp enumerator">
258 <dt id="_CPPv4N16memcached_hash_t18MEMCACHED_HASH_MD5E">
259 <span id="_CPPv3N16memcached_hash_t18MEMCACHED_HASH_MD5E"></span><span id="_CPPv2N16memcached_hash_t18MEMCACHED_HASH_MD5E"></span><em class="property">enumerator </em><code class="sig-name descname">MEMCACHED_HASH_MD5</code><a class="headerlink" href="#_CPPv4N16memcached_hash_t18MEMCACHED_HASH_MD5E" title="Permalink to this definition"></a><br /></dt>
260 <dd></dd></dl>
261
262 <dl class="cpp enumerator">
263 <dt id="_CPPv4N16memcached_hash_t18MEMCACHED_HASH_CRCE">
264 <span id="_CPPv3N16memcached_hash_t18MEMCACHED_HASH_CRCE"></span><span id="_CPPv2N16memcached_hash_t18MEMCACHED_HASH_CRCE"></span><em class="property">enumerator </em><code class="sig-name descname">MEMCACHED_HASH_CRC</code><a class="headerlink" href="#_CPPv4N16memcached_hash_t18MEMCACHED_HASH_CRCE" title="Permalink to this definition"></a><br /></dt>
265 <dd></dd></dl>
266
267 <dl class="cpp enumerator">
268 <dt id="_CPPv4N16memcached_hash_t22MEMCACHED_HASH_FNV1_64E">
269 <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="sig-name descname">MEMCACHED_HASH_FNV1_64</code><a class="headerlink" href="#_CPPv4N16memcached_hash_t22MEMCACHED_HASH_FNV1_64E" title="Permalink to this definition"></a><br /></dt>
270 <dd></dd></dl>
271
272 <dl class="cpp enumerator">
273 <dt id="_CPPv4N16memcached_hash_t23MEMCACHED_HASH_FNV1A_64E">
274 <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="sig-name descname">MEMCACHED_HASH_FNV1A_64</code><a class="headerlink" href="#_CPPv4N16memcached_hash_t23MEMCACHED_HASH_FNV1A_64E" title="Permalink to this definition"></a><br /></dt>
275 <dd></dd></dl>
276
277 <dl class="cpp enumerator">
278 <dt id="_CPPv4N16memcached_hash_t22MEMCACHED_HASH_FNV1_32E">
279 <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="sig-name descname">MEMCACHED_HASH_FNV1_32</code><a class="headerlink" href="#_CPPv4N16memcached_hash_t22MEMCACHED_HASH_FNV1_32E" title="Permalink to this definition"></a><br /></dt>
280 <dd></dd></dl>
281
282 <dl class="cpp enumerator">
283 <dt id="_CPPv4N16memcached_hash_t23MEMCACHED_HASH_FNV1A_32E">
284 <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="sig-name descname">MEMCACHED_HASH_FNV1A_32</code><a class="headerlink" href="#_CPPv4N16memcached_hash_t23MEMCACHED_HASH_FNV1A_32E" title="Permalink to this definition"></a><br /></dt>
285 <dd></dd></dl>
286
287 <dl class="cpp enumerator">
288 <dt id="_CPPv4N16memcached_hash_t20MEMCACHED_HASH_HSIEHE">
289 <span id="_CPPv3N16memcached_hash_t20MEMCACHED_HASH_HSIEHE"></span><span id="_CPPv2N16memcached_hash_t20MEMCACHED_HASH_HSIEHE"></span><em class="property">enumerator </em><code class="sig-name descname">MEMCACHED_HASH_HSIEH</code><a class="headerlink" href="#_CPPv4N16memcached_hash_t20MEMCACHED_HASH_HSIEHE" title="Permalink to this definition"></a><br /></dt>
290 <dd></dd></dl>
291
292 <dl class="cpp enumerator">
293 <dt id="_CPPv4N16memcached_hash_t21MEMCACHED_HASH_MURMURE">
294 <span id="_CPPv3N16memcached_hash_t21MEMCACHED_HASH_MURMURE"></span><span id="_CPPv2N16memcached_hash_t21MEMCACHED_HASH_MURMURE"></span><em class="property">enumerator </em><code class="sig-name descname">MEMCACHED_HASH_MURMUR</code><a class="headerlink" href="#_CPPv4N16memcached_hash_t21MEMCACHED_HASH_MURMURE" title="Permalink to this definition"></a><br /></dt>
295 <dd></dd></dl>
296
297 <dl class="cpp enumerator">
298 <dt id="_CPPv4N16memcached_hash_t22MEMCACHED_HASH_JENKINSE">
299 <span id="_CPPv3N16memcached_hash_t22MEMCACHED_HASH_JENKINSE"></span><span id="_CPPv2N16memcached_hash_t22MEMCACHED_HASH_JENKINSE"></span><em class="property">enumerator </em><code class="sig-name descname">MEMCACHED_HASH_JENKINS</code><a class="headerlink" href="#_CPPv4N16memcached_hash_t22MEMCACHED_HASH_JENKINSE" title="Permalink to this definition"></a><br /></dt>
300 <dd></dd></dl>
301
302 <dl class="cpp enumerator">
303 <dt id="_CPPv4N16memcached_hash_t22MEMCACHED_HASH_MURMUR3E">
304 <span id="_CPPv3N16memcached_hash_t22MEMCACHED_HASH_MURMUR3E"></span><span id="_CPPv2N16memcached_hash_t22MEMCACHED_HASH_MURMUR3E"></span><em class="property">enumerator </em><code class="sig-name descname">MEMCACHED_HASH_MURMUR3</code><a class="headerlink" href="#_CPPv4N16memcached_hash_t22MEMCACHED_HASH_MURMUR3E" title="Permalink to this definition"></a><br /></dt>
305 <dd></dd></dl>
306
307 <dl class="cpp enumerator">
308 <dt id="_CPPv4N16memcached_hash_t21MEMCACHED_HASH_CUSTOME">
309 <span id="_CPPv3N16memcached_hash_t21MEMCACHED_HASH_CUSTOME"></span><span id="_CPPv2N16memcached_hash_t21MEMCACHED_HASH_CUSTOME"></span><em class="property">enumerator </em><code class="sig-name descname">MEMCACHED_HASH_CUSTOM</code><a class="headerlink" href="#_CPPv4N16memcached_hash_t21MEMCACHED_HASH_CUSTOME" title="Permalink to this definition"></a><br /></dt>
310 <dd></dd></dl>
311
312 </dd></dl>
313
314 </div>
315 <div class="section" id="description">
316 <h2>DESCRIPTION<a class="headerlink" href="#description" title="Permalink to this headline"></a></h2>
317 <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
318 the hash functions defined in the library. This method is provided for
319 the convenience of higher-level language bindings and is not necessary
320 for normal memcache operations.</p>
321 <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
322 disabled by default. To enable tests for this hashing algorithm,
323 configure and build libmemcached with the Hsieh hash enabled.</p>
324 <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
325 and produces the hash value that would have been generated based on the
326 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>
327 <p>As of version 0.36 all hash methods have been placed into the library
328 libhashkit(3) which is linked with libmemcached(3). For more information please see its documentation.</p>
329 </div>
330 <div class="section" id="return-value">
331 <h2>RETURN VALUE<a class="headerlink" href="#return-value" title="Permalink to this headline"></a></h2>
332 <p>A 32-bit integer which is the result of hashing the given key.
333 For 64-bit hash algorithms, only the least-significant 32 bits are
334 returned.</p>
335 </div>
336 <div class="section" id="see-also">
337 <h2>SEE ALSO<a class="headerlink" href="#see-also" title="Permalink to this headline"></a></h2>
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