93 lines
6.6 KiB
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93 lines
6.6 KiB
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<h1 id="firstHeading" class="firstHeading"><code>std::tuple</code> 的推导指引</h1>
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-utility.html">utility</a>‎ | <a href="cpp-utility-tuple.html">tuple</a></span></div>
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<div>定义于头文件 <code><a href="cpp-header-tuple.html"><tuple></a></code></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span><span class="kw1">class</span>... <span class="me1">UTypes</span><span class="sy1">></span><br />
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tuple<span class="br0">(</span>UTypes...<span class="br0">)</span> <span class="sy2">-</span><span class="sy1">></span> tuple<span class="sy1"><</span>UTypes...<span class="sy1">></span><span class="sy4">;</span></span></div>
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<td>(1)</td>
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<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span><span class="kw1">class</span> T1, <span class="kw1">class</span> T2<span class="sy1">></span><br />
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tuple<span class="br0">(</span><a href="cpp-utility-pair.html"><span class="kw1096">std::<span class="me2">pair</span></span></a><span class="sy1"><</span>T1, T2<span class="sy1">></span><span class="br0">)</span> <span class="sy2">-</span><span class="sy1">></span> tuple<span class="sy1"><</span>T1, T2<span class="sy1">></span><span class="sy4">;</span></span></div>
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<td>(2)</td>
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<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span><span class="kw1">class</span> Alloc, <span class="kw1">class</span>... <span class="me1">UTypes</span><span class="sy1">></span><br />
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tuple<span class="br0">(</span><a href="cpp-memory-allocator_arg_t.html"><span class="kw702">std::<span class="me2">allocator_arg_t</span></span></a>, Alloc, UTypes...<span class="br0">)</span> <span class="sy2">-</span><span class="sy1">></span> tuple<span class="sy1"><</span>UTypes...<span class="sy1">></span><span class="sy4">;</span></span></div>
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<td>(3)</td>
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<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span><span class="kw1">class</span> Alloc, <span class="kw1">class</span> T1, <span class="kw1">class</span> T2<span class="sy1">></span><br />
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tuple<span class="br0">(</span><a href="cpp-memory-allocator_arg_t.html"><span class="kw702">std::<span class="me2">allocator_arg_t</span></span></a>, Alloc, <a href="cpp-utility-pair.html"><span class="kw1096">std::<span class="me2">pair</span></span></a><span class="sy1"><</span>T1, T2<span class="sy1">></span><span class="br0">)</span> <span class="sy2">-</span><span class="sy1">></span> tuple<span class="sy1"><</span>T1, T2<span class="sy1">></span><span class="sy4">;</span></span></div>
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<td>(4)</td>
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<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span><span class="kw1">class</span> Alloc, <span class="kw1">class</span>... <span class="me1">UTypes</span><span class="sy1">></span><br />
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tuple<span class="br0">(</span><a href="cpp-memory-allocator_arg_t.html"><span class="kw702">std::<span class="me2">allocator_arg_t</span></span></a>, Alloc, tuple<span class="sy1"><</span>UTypes...<span class="sy1">></span><span class="br0">)</span> <span class="sy2">-</span><span class="sy1">></span> tuple<span class="sy1"><</span>UTypes...<span class="sy1">></span><span class="sy4">;</span></span></div>
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<td>(5)</td>
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<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span></td>
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<p>为 <span class="t-lc"><a href="cpp-utility-tuple.html">std::tuple</a></span> 提供这些<a href="cpp-language-class_template_argument_deduction.html">推导指引</a>，以涵盖隐式推导指引缺失的极端情况，特别是不可复制参数和数组到指针转换。</p>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
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<div class="cpp source-cpp">
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<pre class="de1"><span class="co2">#include <tuple></span>
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<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
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<span class="br0">{</span>
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<span class="kw4">int</span> a<span class="br0">[</span><span class="nu0">2</span><span class="br0">]</span>, b<span class="br0">[</span><span class="nu0">3</span><span class="br0">]</span>, c<span class="br0">[</span><span class="nu0">4</span><span class="br0">]</span><span class="sy4">;</span>
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<a href="cpp-utility-tuple.html"><span class="kw1098">std::<span class="me2">tuple</span></span></a> t1<span class="br0">{</span>a, b, c<span class="br0">}</span><span class="sy4">;</span> <span class="co1">// 用于此场合的显式推导指引</span>
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<span class="br0">}</span></pre></div>
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