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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::ranges::</span>view_interface</h1>
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<div id="contentSub"><span class="subpages">&lt; <a href="cpp.html">cpp</a>&lrm; | <a href="cpp-ranges.html">ranges</a></span></div>
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<div>&#23450;&#20041;&#20110;&#22836;&#25991;&#20214; <code><a href="cpp-header-ranges.html">&lt;ranges&gt;</a></code></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1">&lt;</span><span class="kw1">class</span> D<span class="sy1">&gt;</span><br /></span>
<p>&nbsp; requires <a href="cpp-types-is_class.html"><span class="kw477">std::<span class="me2">is_class_v</span></span></a><span class="sy1">&lt;</span>D<span class="sy1">&gt;</span> <span class="sy3">&amp;&amp;</span> std<span class="sy4">::</span><span class="me2">same_as</span><span class="sy1">&lt;</span>D, <a href="cpp-types-remove_cv.html"><span class="kw597">std::<span class="me2">remove_cv_t</span></span></a><span class="sy1">&lt;</span>D<span class="sy1">&gt;&gt;</span><br /></p>
<span class="kw1">class</span> view_interface<span class="sy4">;</span></div>
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<td class="t-dcl-nopad"></td>
<td><span class="t-mark-rev t-since-cxx20">(C++20 &#36215;)</span></td>
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<p><code>std::ranges::view_interface</code> &#26159;&#29992;&#20110;&#23450;&#20041;&#33539;&#22260;&#25509;&#21475;&#30340;&#36741;&#21161;&#31867;&#27169;&#26495;&#12290;</p>
<p><code>view_interface</code> &#24120;&#20197; <a href="https://zh.cppreference.com/mwiki/index.php?title=cpp/language/crtp&amp;action=edit&amp;redlink=1" class="new" title="cpp/language/crtp&#65288;&#39029;&#38754;&#19981;&#23384;&#22312;&#65289;">CRTP</a> &#20351;&#29992;&#65306;</p>
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<pre class="de1"><span class="kw1">class</span> my_view <span class="sy4">:</span> <span class="kw1">public</span> std<span class="sy4">::</span><span class="me2">ranges</span><span class="sy4">::</span><span class="me2">view_interface</span><span class="sy1">&lt;</span>my_view<span class="sy1">&gt;</span> <span class="br0">{</span>
<span class="kw1">public</span><span class="sy4">:</span>
<span class="kw4">auto</span> begin<span class="br0">(</span><span class="br0">)</span> <span class="kw4">const</span> <span class="br0">{</span> <span class="coMULTI">/*...*/</span> <span class="br0">}</span>
<span class="kw4">auto</span> end<span class="br0">(</span><span class="br0">)</span> <span class="kw4">const</span> <span class="br0">{</span> <span class="coMULTI">/*...*/</span> <span class="br0">}</span>
<span class="co1">// &#33509; begin() &#36820;&#22238;&#21521;&#21069;&#36845;&#20195;&#22120;&#19988; end() &#36820;&#22238;&#20854;&#21736;&#20301;&#21017;&#25552;&#20379; empty() &#12290;</span>
<span class="br0">}</span><span class="sy4">;</span></pre></div>
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<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E5.87.BD.E6.95.B0">&#25104;&#21592;&#20989;&#25968;</span></h3>
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<div><a href="cpp-ranges-view_interface-empty.html"><span class="t-lines"><span>empty</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
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<td>&#36820;&#22238;&#35270;&#22270;&#26159;&#21542;&#20026;&#31354;&#12290;&#33509;&#35270;&#22270;&#28385;&#36275; <a href="cpp-ranges-forward_range.html"><code>forward_range</code></a> &#21017;&#25552;&#20379;&#12290;<br />
<span class="t-mark">(&#20844;&#24320;&#25104;&#21592;&#20989;&#25968;)</span></td>
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<div><a href="cpp-ranges-view_interface-operator_bool.html"><span class="t-lines"><span>operator bool</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
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<td>&#36820;&#22238;&#27966;&#29983;&#35270;&#22270;&#26159;&#21542;&#20026;&#38750;&#31354;&#12290;&#33509; <span class="t-lc">ranges::empty</span> &#21487;&#24212;&#29992;&#20110;&#23427;&#21017;&#25552;&#20379;&#12290;<br />
<span class="t-mark">(&#20844;&#24320;&#25104;&#21592;&#20989;&#25968;)</span></td>
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<div><a href="cpp-ranges-view_interface-data.html"><span class="t-lines"><span>data</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
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<td>&#36820;&#22238;&#27966;&#29983;&#35270;&#22270;&#30340;&#25968;&#25454;&#30340;&#22320;&#22336;&#12290;&#33509;&#35270;&#22270;&#30340;&#36845;&#20195;&#22120;&#31867;&#22411;&#28385;&#36275; <a href="cpp-iterator-contiguous_iterator.html"><code>contiguous_iterator</code></a> &#21017;&#25552;&#20379;&#12290;<br />
<span class="t-mark">(&#20844;&#24320;&#25104;&#21592;&#20989;&#25968;)</span></td>
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<div><a href="cpp-ranges-view_interface-size.html"><span class="t-lines"><span>size</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
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<td>&#36820;&#22238;&#27966;&#29983;&#35270;&#22270;&#20013;&#30340;&#20803;&#32032;&#25968;&#12290;&#33509;&#35270;&#22270;&#28385;&#36275; <a href="cpp-ranges-forward_range.html"><code>forward_range</code></a> &#19988;&#20854;&#21736;&#20301;&#19982;&#36845;&#20195;&#22120;&#31867;&#22411;&#28385;&#36275; <a href="cpp-iterator-sized_sentinel_for.html"><code>sized_sentinel_for</code></a> &#21017;&#25552;&#20379;&#12290;<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-ranges-view_interface-front.html"><span class="t-lines"><span>front</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
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<td>&#36820;&#22238;&#27966;&#29983;&#35270;&#22270;&#20013;&#30340;&#39318;&#20803;&#32032;&#12290;&#33509;&#35270;&#22270;&#28385;&#36275; <a href="cpp-ranges-forward_range.html"><code>forward_range</code></a> &#21017;&#25552;&#20379;&#12290;<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-ranges-view_interface-back.html"><span class="t-lines"><span>back</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
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<td>&#36820;&#22238;&#27966;&#29983;&#35270;&#22270;&#20013;&#30340;&#26411;&#20803;&#32032;&#12290;&#33509;&#35270;&#22270;&#28385;&#36275; <a href="cpp-ranges-bidirectional_range.html"><code>bidirectional_range</code></a> &#19982; <a href="cpp-ranges-common_range.html"><code>common_range</code></a> &#21017;&#25552;&#20379;&#12290;<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-ranges-view_interface-operator_at.html"><span class="t-lines"><span>operator[]</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
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<td>&#36820;&#22238;&#27966;&#29983;&#35270;&#22270;&#20013;&#30340;&#31532; n &#20010;&#20803;&#32032;&#12290;&#33509;&#35270;&#22270;&#28385;&#36275; <a href="cpp-ranges-random_access_range.html"><code>random_access_range</code></a> &#21017;&#25552;&#20379;&#12290;<br />
<span class="t-mark">(&#20844;&#24320;&#25104;&#21592;&#20989;&#25968;)</span></td>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">&#31034;&#20363;</span></h3>
<div class="t-example">
<div class="t-example-live-link"></div>
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<div class="cpp source-cpp">
<pre class="de1"><span class="co2">#include &lt;ranges&gt;</span>
<span class="co2">#include &lt;vector&gt;</span>
<span class="co2">#include &lt;iostream&gt;</span>
<span class="kw1">template</span> <span class="sy1">&lt;</span><span class="kw1">class</span> T, <span class="kw1">class</span> A<span class="sy1">&gt;</span>
<span class="kw1">class</span> VectorView <span class="sy4">:</span> <span class="kw1">public</span> std<span class="sy4">::</span><span class="me2">ranges</span><span class="sy4">::</span><span class="me2">view_interface</span><span class="sy1">&lt;</span>VectorView<span class="sy1">&lt;</span>T, A<span class="sy1">&gt;&gt;</span> <span class="br0">{</span>
<span class="kw1">public</span><span class="sy4">:</span>
VectorView<span class="br0">(</span><span class="br0">)</span> <span class="sy1">=</span> <span class="kw1">default</span><span class="sy4">;</span>
VectorView<span class="br0">(</span><span class="kw4">const</span> <a href="cpp-container-vector.html"><span class="kw1269">std::<span class="me2">vector</span></span></a><span class="sy1">&lt;</span>T, A<span class="sy1">&gt;</span><span class="sy3">&amp;</span> vec<span class="br0">)</span> <span class="sy4">:</span>
m_begin<span class="br0">(</span>vec.<span class="me1">cbegin</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span>, m_end<span class="br0">(</span>vec.<span class="me1">cend</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span> <span class="br0">{</span><span class="br0">}</span>
<span class="kw4">auto</span> begin<span class="br0">(</span><span class="br0">)</span> <span class="kw4">const</span> <span class="br0">{</span> <span class="kw1">return</span> m_begin<span class="sy4">;</span> <span class="br0">}</span>
<span class="kw4">auto</span> end<span class="br0">(</span><span class="br0">)</span> <span class="kw4">const</span> <span class="br0">{</span> <span class="kw1">return</span> m_end<span class="sy4">;</span> <span class="br0">}</span>
<span class="kw1">private</span><span class="sy4">:</span>
<span class="kw1">typename</span> <a href="cpp-container-vector.html"><span class="kw1269">std::<span class="me2">vector</span></span></a><span class="sy1">&lt;</span>T, A<span class="sy1">&gt;</span><span class="sy4">::</span><span class="me2">const_iterator</span> m_begin<span class="br0">{</span><span class="br0">}</span>, m_end<span class="br0">{</span><span class="br0">}</span><span class="sy4">;</span>
<span class="br0">}</span><span class="sy4">;</span>
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
<span class="br0">{</span>
<a href="cpp-container-vector.html"><span class="kw1269">std::<span class="me2">vector</span></span></a><span class="sy1">&lt;</span><span class="kw4">int</span><span class="sy1">&gt;</span> v <span class="sy1">=</span> <span class="br0">{</span><span class="nu0">1</span>, <span class="nu0">4</span>, <span class="nu0">9</span>, <span class="nu0">16</span><span class="br0">}</span><span class="sy4">;</span>
VectorView view_over_v<span class="br0">{</span>v<span class="br0">}</span><span class="sy4">;</span>
<span class="co1">// &#25105;&#20204;&#33021;&#20197; begin() &#19982; end() &#36845;&#20195;&#12290;</span>
<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">int</span> n <span class="sy4">:</span> view_over_v<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> n <span class="sy1">&lt;&lt;</span> <span class="st0">&#39; &#39;</span><span class="sy4">;</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> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
<span class="co1">// &#25105;&#20204;&#33021;&#22312;&#32487;&#25215; view_interface &#26102;&#20813;&#36153;&#22320;&#33719;&#24471; operator[]</span>
<span class="co1">// &#22240;&#20026;&#25105;&#20204;&#28385;&#36275; random_access_range &#27010;&#24565;&#12290;</span>
<span class="kw1">for</span> <span class="br0">(</span><a href="cpp-types-ptrdiff_t.html"><span class="kw101">std::<span class="me2">ptrdiff_t</span></span></a> i <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span> i <span class="sy1">&lt;</span> view_over_v.<span class="me1">size</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span> i<span class="sy2">++</span><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> <span class="st0">&quot;v[&quot;</span> <span class="sy1">&lt;&lt;</span> i <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;] = &quot;</span> <span class="sy1">&lt;&lt;</span> view_over_v<span class="br0">[</span>i<span class="br0">]</span> <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="br0">}</span></pre></div>
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<p>&#36755;&#20986;&#65306;</p>
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<div class="text source-text">
<pre class="de1">1 4 9 16
v[0] = 1
v[1] = 4
v[2] = 9
v[3] = 16</pre></div>
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<h3><span class="mw-headline" id=".E7.BC.BA.E9.99.B7.E6.8A.A5.E5.91.8A">&#32570;&#38519;&#25253;&#21578;</span></h3>
<p>&#19979;&#21015;&#26356;&#25913;&#34892;&#20026;&#30340;&#32570;&#38519;&#25253;&#21578;&#36861;&#28335;&#22320;&#24212;&#29992;&#20110;&#20197;&#21069;&#20986;&#29256;&#30340; C++ &#26631;&#20934;&#12290;</p>
<table class="dsctable" style="font-size:0.8em">
<tr>
<th>DR</th>
<th>&#24212;&#29992;&#20110;</th>
<th>&#20986;&#29256;&#26102;&#30340;&#34892;&#20026;</th>
<th>&#27491;&#30830;&#34892;&#20026;</th>
</tr>
<tr>
<td><a rel="nofollow" class="external text" href="https://cplusplus.github.io/LWG/issue3549">LWG 3549</a></td>
<td>C++20</td>
<td>&#35201;&#27714; <code>view_interface</code> &#27966;&#29983;&#33258; <code>view_base</code> &#65292;&#36825;&#26377;&#26102;&#35201;&#27714;&#35270;&#22270;&#20013;&#30340;&#22810;&#20010; <code>view_base</code> &#23376;&#23545;&#35937;</td>
<td>&#31227;&#38500;&#32487;&#25215;</td>
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</table>
<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">&#21442;&#38405;</span></h3>
<table class="t-dsc-begin">
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<div class="t-dsc-member-div">
<div><a href="cpp-ranges-subrange.html"><span class="t-lines"><span>ranges::subrange</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
</div>
</td>
<td>&#23558;&#36845;&#20195;&#22120;/&#21736;&#20301;&#23545;&#32467;&#21512;&#20026;&#19968;&#20010; <a href="cpp-ranges-view.html"><code>view</code></a><br />
<span class="t-mark">(&#31867;&#27169;&#26495;)</span></td>
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</table>
</div>
<div class="visualClear"></div>
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