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<div class="identifier-type">function</div><div class="header"><memory></div><h1 itemprop="name"><span class="namespace" title="namespace std">std::</span><span class="class" title="class shared_ptr">shared_ptr::</span><span class="token">unique</span><span class="cpp cpp11" title="C++11で追加">(C++11)</span><span class="cpp cpp17deprecated text-warning" title="C++17で非推奨">(C++17で非推奨)</span><span class="cpp cpp20removed text-danger" title="C++20で削除">(C++20で削除)</span></h1>
<div itemprop="articleBody"><p><div class="codehilite"><pre><span></span><code><span class="kt">bool</span><span class="w"> </span><span class="nf">unique</span><span class="p">()</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="k">noexcept</span><span class="p">;</span>
</code></pre></div>
</p>
<p>この関数は、C++17から非推奨となり、C++20で削除された。代わりに<code><a href="use_count.html">use_count()</a></code>関数を使用すること。</p>
<h2>概要</h2>
<p>同じ所有権を共有する他のユーザーが存在しないかを判定する。</p>
<h2><a class="cpprefjp-defined-word" data-desc="関数呼び出し式の評価結果となるオブジェクト・値">戻り値</a></h2>
<p><div class="codehilite"><pre><span></span><code><span class="n"><a href="use_count.html">use_count()</a></span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">1</span>
</code></pre></div>
</p>
<h2>備考</h2>
<p>この関数は、<code><a href="use_count.html">use_count()</a></code>を使用するよりも高速である可能性がある。</p>
<h2>非推奨・削除の詳細</h2>
<p>所有権を持つユーザー数を複数スレッドの状況で取得した場合、その値は参考程度にしかならない。そのため、<code><a href="use_count.html">use_count()</a></code>は参考値として使用できるが、この関数は厳密な値を要求してしまう。そのために、複数スレッドで危険なこの関数は非推奨とし、<code><a href="use_count.html">use_count()</a></code>を推奨する。</p>
<h2>例</h2>
<p><div class="yata" id="0b2b1619470a1517989aad3e89c35df153b51be3"><div class="codehilite"><pre><span></span><code><span class="cp">#include <a href="../../iostream.html"><iostream></a></span>
<span class="cp">#include <a href="../../memory.html"><memory></a></span>
<span class="kt">int</span><span class="w"> </span><span class="nf">main</span><span class="p">()</span>
<span class="p">{</span>
<span class="w"> </span><span class="n"><a href="../shared_ptr.html">std::shared_ptr</a></span><span class="o"><</span><span class="kt">int</span><span class="o">></span><span class="w"> </span><span class="n">p</span><span class="p">(</span><span class="k">new</span><span class="w"> </span><span class="kt">int</span><span class="p">(</span><span class="mi">3</span><span class="p">));</span>
<span class="w"> </span><span class="c1">// 所有権を持つユーザーが1人</span>
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">p</span><span class="p">.</span><span class="n"><span style="color:#ff0000">unique()</span></span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="n"><a href="../../iostream/cout.html">std::cout</a></span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"unique"</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="../../ostream/endl.html">std::endl</a></span><span class="p">;</span>
<span class="w"> </span><span class="p">}</span>
<span class="w"> </span><span class="c1">// 所有権を持つユーザーが2人</span>
<span class="w"> </span><span class="n"><a href="../shared_ptr.html">std::shared_ptr</a></span><span class="o"><</span><span class="kt">int</span><span class="o">></span><span class="w"> </span><span class="n">q</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">p</span><span class="p">;</span>
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="o">!</span><span class="n">p</span><span class="p">.</span><span class="n"><span style="color:#ff0000">unique()</span></span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="n"><a href="../../iostream/cout.html">std::cout</a></span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"non unique"</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="../../ostream/endl.html">std::endl</a></span><span class="p">;</span>
<span class="w"> </span><span class="p">}</span>
<span class="p">}</span>
</code></pre></div>
</div></p>
<h3>出力</h3>
<p><pre><code>unique
non unique
</code></pre></p>
<h2>バージョン</h2>
<h3>言語</h3>
<ul>
<li>C++11</li>
</ul>
<h3>処理系</h3>
<ul>
<li><a href="../../../implementation.html#gcc">GCC</a>: 4.4.7 <span aria-label="検証済" role="img" title="検証済">✅</span></li>
<li><a href="../../../implementation.html#clang">Clang</a>: 3.0 <span aria-label="検証済" role="img" title="検証済">✅</span></li>
<li><a href="../../../implementation.html#icc">ICC</a>: ?</li>
<li><a href="../../../implementation.html#visual_cpp">Visual C++</a>: 2008 (TR1) <span aria-label="検証済" role="img" title="検証済">✅</span>, 2010 <span aria-label="検証済" role="img" title="検証済">✅</span>, 2012 <span aria-label="検証済" role="img" title="検証済">✅</span>, 2013 <span aria-label="検証済" role="img" title="検証済">✅</span></li>
</ul>
<h2>参照</h2>
<ul>
<li><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0521r0.html" target="_blank">P0521R0 Proposed Resolution for CA 14 (<code>shared_ptr use_count</code>/<code>unique</code>)</a></li>
<li><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0619r4.html" target="_blank">P0619R4 Reviewing deprecated facilities of C++17 for C++20</a></li>
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