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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::filesystem::</span>hash_value</h1>
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<div id="contentSub"><span class="subpages">&lt; <a href="cpp.html">cpp</a>&lrm; | <a href="cpp-filesystem.html">filesystem</a>&lrm; | <a href="cpp-filesystem-path.html">path</a></span></div>
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<div>&#23450;&#20041;&#20110;&#22836;&#25991;&#20214; <code><a href="cpp-header-filesystem.html">&lt;filesystem&gt;</a></code></div>
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<div><span class="mw-geshi cpp source-cpp"><a href="cpp-types-size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a> hash_value<span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-filesystem-path.html"><span class="kw2199">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">path</span></span></a><span class="sy3">&amp;</span> p <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></td>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
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<td>p</td>
<td>-</td>
<td><span class="t-lc"><a href="cpp-filesystem-path.html">std::filesystem::path</a></span> &#23545;&#35937;</td>
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<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">&#36820;&#22238;&#20540;</span></h3>
<p>&#21704;&#24076;&#20540;&#65292;&#28385;&#36275;&#33509;&#23545;&#20110;&#20108;&#20010;&#36335;&#24452;&#26377; {c|1=p1 == p2}} &#21017; <span class="t-c"><span class="mw-geshi cpp source-cpp">hash_value<span class="br0">(</span>p1<span class="br0">)</span> <span class="sy1">==</span> hash_value<span class="br0">(</span>p2<span class="br0">)</span></span></span> &#12290;</p>
<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">&#27880;&#35299;</span></h3>
<p>&#20108;&#20010;&#36335;&#24452;&#30340;&#30456;&#31561;&#26159;&#20998;&#31163;&#27604;&#36739;&#27599;&#20010;&#32452;&#20998;&#26469;&#30830;&#23450;&#30340;&#65292;&#25925;&#20363;&#22914; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="st0">&quot;a//b&quot;</span></span></span> &#31561;&#20110; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="st0">&quot;a/b&quot;</span></span></span> &#19988;&#25317;&#26377;&#30456;&#21516;&#30340; <code>hash_value</code> &#12290;</p>
<p><code>hash_value</code> &#28304;&#20110; <a rel="nofollow" class="external text" href="https://www.boost.org/doc/libs/release/libs/filesystem/doc/index.htm">Boost.filesystem</a> &#24211;&#65292;&#20854;&#20013;&#23427;&#22240;&#19982; boost.hash &#65288;&#22312;&#21487;&#29992;&#22788;&#35843;&#29992;<a href="cpp-language-adl.html">&#23454;&#21442;&#20381;&#36182;&#26597;&#25214;</a>&#25152;&#25214;&#21040;&#30340; <code>hash_value</code> &#25110; <a rel="nofollow" class="external text" href="https://www.boost.org/doc/libs/1_76_0/doc/html/hash/reference.html"><code>boost::hash_value</code></a> &#65289;&#30340;&#20114;&#21160;&#33021;&#21147;&#24471;&#21040;&#20351;&#29992;&#12290;</p>
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">&#31034;&#20363;</span></h3>
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<pre class="de1"><span class="co2">#include &lt;cassert&gt;</span>
<span class="co2">#include &lt;cstddef&gt;</span>
<span class="co2">#include &lt;iomanip&gt;</span>
<span class="co2">#include &lt;iostream&gt;</span>
<span class="co2">#include &lt;filesystem&gt;</span>
<span class="co2">#include &lt;unordered_set&gt;</span>
<span class="kw1">namespace</span> fs <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">filesystem</span><span class="sy4">;</span>
<span class="kw4">void</span> show_hash<span class="br0">(</span>fs<span class="sy4">::</span><span class="me2">path</span> <span class="kw4">const</span><span class="sy3">&amp;</span> p<span class="br0">)</span>
<span class="br0">{</span>
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <a href="cpp-io-manip-hex.html"><span class="kw1782">std::<span class="me2">hex</span></span></a> <span class="sy1">&lt;&lt;</span> <a href="cpp-io-manip-uppercase.html"><span class="kw1774">std::<span class="me2">uppercase</span></span></a> <span class="sy1">&lt;&lt;</span> <a href="cpp-io-manip-setw.html"><span class="kw1797">std::<span class="me2">setw</span></span></a><span class="br0">(</span><span class="nu0">16</span><span class="br0">)</span>
<span class="sy1">&lt;&lt;</span> fs<span class="sy4">::</span><span class="me2">hash_value</span><span class="br0">(</span>p<span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&quot; : &quot;</span> <span class="sy1">&lt;&lt;</span> p <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
<span class="br0">}</span>
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
<span class="br0">{</span>
<span class="kw4">auto</span> tmp1 <span class="sy1">=</span> fs<span class="sy4">::</span><span class="me2">path</span><span class="br0">{</span><span class="st0">&quot;/tmp&quot;</span><span class="br0">}</span><span class="sy4">;</span>
<span class="kw4">auto</span> tmp2 <span class="sy1">=</span> fs<span class="sy4">::</span><span class="me2">path</span><span class="br0">{</span><span class="st0">&quot;/tmp/../tmp&quot;</span><span class="br0">}</span><span class="sy4">;</span>
<a href="cpp-error-assert.html"><span class="kw774">assert</span></a><span class="br0">(</span> <span class="sy3">!</span> <span class="br0">(</span>tmp1 <span class="sy1">==</span> tmp2<span class="br0">)</span> <span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-error-assert.html"><span class="kw774">assert</span></a><span class="br0">(</span> fs<span class="sy4">::</span><span class="me2">equivalent</span><span class="br0">(</span>tmp1, tmp2<span class="br0">)</span> <span class="br0">)</span><span class="sy4">;</span>
show_hash<span class="br0">(</span> tmp1 <span class="br0">)</span><span class="sy4">;</span>
show_hash<span class="br0">(</span> tmp2 <span class="br0">)</span><span class="sy4">;</span>
<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">auto</span> s <span class="sy4">:</span> <span class="br0">{</span><span class="st0">&quot;/a///b&quot;</span>, <span class="st0">&quot;/a//b&quot;</span>, <span class="st0">&quot;/a/c&quot;</span>, <span class="st0">&quot;...&quot;</span>, <span class="st0">&quot;..&quot;</span>, <span class="st0">&quot;.&quot;</span>, <span class="st0">&quot;&quot;</span><span class="br0">}</span><span class="br0">)</span>
show_hash<span class="br0">(</span>s<span class="br0">)</span><span class="sy4">;</span>
<span class="co1">// A hash function object to work with unordered_* containers:</span>
<span class="kw1">struct</span> PathHash <span class="br0">{</span>
<a href="cpp-types-size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a> operator<span class="br0">(</span><span class="br0">)</span><span class="br0">(</span>fs<span class="sy4">::</span><span class="me2">path</span> <span class="kw4">const</span><span class="sy3">&amp;</span> p<span class="br0">)</span> <span class="kw4">const</span> <span class="kw1">noexcept</span> <span class="br0">{</span>
<span class="kw1">return</span> fs<span class="sy4">::</span><span class="me2">hash_value</span><span class="br0">(</span>p<span class="br0">)</span><span class="sy4">;</span>
<span class="br0">}</span>
<span class="br0">}</span><span class="sy4">;</span>
<a href="cpp-container-unordered_set.html"><span class="kw1289">std::<span class="me2">unordered_set</span></span></a><span class="sy1">&lt;</span>fs<span class="sy4">::</span><span class="me2">path</span>, PathHash<span class="sy1">&gt;</span> dirs <span class="br0">{</span>
<span class="st0">&quot;/bin&quot;</span>, <span class="st0">&quot;/bin&quot;</span>, <span class="st0">&quot;/lib&quot;</span>, <span class="st0">&quot;/lib&quot;</span>, <span class="st0">&quot;/opt&quot;</span>, <span class="st0">&quot;/opt&quot;</span>, <span class="st0">&quot;/tmp&quot;</span>, <span class="st0">&quot;/tmp/../tmp&quot;</span>
<span class="br0">}</span><span class="sy4">;</span>
<span class="kw1">for</span> <span class="br0">(</span>fs<span class="sy4">::</span><span class="me2">path</span> <span class="kw4">const</span><span class="sy3">&amp;</span> p<span class="sy4">:</span> dirs<span class="br0">)</span> <span class="br0">{</span> <a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> p <span class="sy1">&lt;&lt;</span> <span class="st0">&#39; &#39;</span><span class="sy4">;</span> <span class="br0">}</span>
<span class="br0">}</span></pre></div>
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<p>&#21487;&#33021;&#30340;&#36755;&#20986;&#65306;</p>
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<pre class="de1">6050C47ADB62DFE5 : &quot;/tmp&quot;
62795A58B69AD90A : &quot;/tmp/../tmp&quot;
FF302110C9991974 : &quot;/a///b&quot;
FF302110C9991974 : &quot;/a//b&quot;
FD6167277915D464 : &quot;/a/c&quot;
C42040F82CD8B542 : &quot;...&quot;
D2D30154E0B78BBC : &quot;..&quot;
D18C722215ED0530 : &quot;.&quot;
0 : &quot;&quot;
&quot;/tmp/../tmp&quot; &quot;/opt&quot; &quot;/lib&quot; &quot;/tmp&quot; &quot;/bin&quot;</pre></div>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">&#21442;&#38405;</span></h3>
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<div><a href="cpp-filesystem-path-compare.html"><span class="t-lines"><span>compare</span></span></a></div>
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<td>&#20197;&#23383;&#20856;&#24207;&#27604;&#36739;&#20108;&#20010;&#36335;&#24452;&#30340;&#23383;&#20856;&#34920;&#31034;<br />
<span class="t-mark">(&#20844;&#24320;&#25104;&#21592;&#20989;&#25968;)</span></td>
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<div class="t-dsc-member-div">
<div><a href="cpp-filesystem-path-operator_cmp.html"><span class="t-lines"><span>operator==</span><span>operator!=</span><span>operator&lt;</span><span>operator&lt;=</span><span>operator&gt;</span><span>operator&gt;=</span><span>operator&lt;=&gt;</span></span></a></div>
<div><span class="t-lines"><span></span><span><span class="t-mark-rev t-until-cxx20">(C++20 &#21069;)</span></span><span><span class="t-mark-rev t-until-cxx20">(C++20 &#21069;)</span></span><span><span class="t-mark-rev t-until-cxx20">(C++20 &#21069;)</span></span><span><span class="t-mark-rev t-until-cxx20">(C++20 &#21069;)</span></span><span><span class="t-mark-rev t-until-cxx20">(C++20 &#21069;)</span></span><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
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<td>&#20197;&#23383;&#20856;&#24207;&#27604;&#36739;&#20108;&#20010;&#36335;&#24452;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
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<div class="t-dsc-member-div">
<div><a href="cpp-filesystem-equivalent.html"><span class="t-lines"><span>equivalent</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx17">(C++17)</span></span></span></div>
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<td>&#26816;&#26597;&#20004;&#20010;&#36335;&#24452;&#26159;&#21542;&#25351;&#20195;&#21516;&#19968;&#25991;&#20214;&#31995;&#32479;&#23545;&#35937;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
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<div class="t-dsc-member-div">
<div><a href="cpp-utility-hash.html"><span class="t-lines"><span>hash</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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<td>&#25955;&#21015;&#20989;&#25968;&#23545;&#35937;<br />
<span class="t-mark">(&#31867;&#27169;&#26495;)</span></td>
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