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<title>operator-(std::counted_iterator&lt;I&gt;, std::default_sentinel_t)</title>
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<h1 id="firstHeading" class="firstHeading">operator-<small>(std::counted_iterator&lt;I&gt;, std::default_sentinel_t)</small></h1>
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<div id="contentSub"><span class="subpages">&lt; <a href="cpp.html">cpp</a>&lrm; | <a href="cpp-iterator.html">iterator</a>&lrm; | <a href="cpp-iterator-counted_iterator.html">counted iterator</a></span></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">friend</span> <span class="kw4">constexpr</span> std<span class="sy4">::</span><span class="me2">iter_difference_t</span><span class="sy1">&lt;</span>I<span class="sy1">&gt;</span> operator<span class="sy2">-</span><span class="br0">(</span><br />
&nbsp; <span class="kw4">const</span> counted_iterator<span class="sy3">&amp;</span> x, std<span class="sy4">::</span><span class="me2">default_sentinel_t</span> <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td>(1)</td>
<td><span class="t-mark-rev t-since-cxx20">(C++20 &#36215;)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">friend</span> <span class="kw4">constexpr</span> std<span class="sy4">::</span><span class="me2">iter_difference_t</span><span class="sy1">&lt;</span>I<span class="sy1">&gt;</span> operator<span class="sy2">-</span><span class="br0">(</span><br />
&nbsp; std<span class="sy4">::</span><span class="me2">default_sentinel_t</span>, <span class="kw4">const</span> counted_iterator<span class="sy3">&amp;</span> y <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td>(2)</td>
<td><span class="t-mark-rev t-since-cxx20">(C++20 &#36215;)</span></td>
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<div class="t-li1"><span class="t-li">1)</span> &#36820;&#22238;&#21040;&#26411;&#23614;&#30340;&#36127;&#36317;&#31163;&#12290;</div>
<div class="t-li1"><span class="t-li">2)</span> &#36820;&#22238;&#21040;&#26411;&#23614;&#30340;&#27491;&#36317;&#31163;&#12290;</div>
<p>&#27492;&#20989;&#25968;&#27169;&#26495;&#23545;&#36890;&#24120;<a href="cpp-language-unqualified_lookup.html">&#26080;&#38480;&#23450;</a>&#25110;<a href="cpp-language-qualified_lookup.html">&#26377;&#38480;&#23450;&#26597;&#25214;</a>&#19981;&#21487;&#35265;&#65292;&#32780;&#21482;&#33021;&#22312; <code>std::counted_iterator</code> &#20026;&#21442;&#25968;&#30340;&#20851;&#32852;&#31867;&#26102;&#30001;<a href="cpp-language-adl.html">&#23454;&#21442;&#20381;&#36182;&#26597;&#25214;</a>&#25214;&#21040;&#12290;</p>
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
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<td>x, y</td>
<td>-</td>
<td>&#35201;&#35745;&#31639;&#36317;&#31163;&#30340;&#36845;&#20195;&#22120;&#36866;&#37197;&#22120;</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>
<div class="t-li1"><span class="t-li">1)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">-</span>x.<span class="me1">count</span><span class="br0">(</span><span class="br0">)</span></span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">2)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp">y.<span class="me1">count</span><span class="br0">(</span><span class="br0">)</span></span></span> &#12290;</div>
<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;initializer_list&gt;</span>
<span class="co2">#include &lt;iterator&gt;</span>
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
<span class="br0">{</span>
<span class="kw4">constexpr</span> <span class="kw4">static</span> <span class="kw4">auto</span> v <span class="sy1">=</span> <span class="br0">{</span><span class="nu0">1</span>, <span class="nu0">2</span>, <span class="nu0">3</span>, <span class="nu0">4</span><span class="br0">}</span><span class="sy4">;</span>
<span class="kw4">constexpr</span> std<span class="sy4">::</span><span class="me2">counted_iterator</span><span class="sy1">&lt;</span><a href="cpp-utility-initializer_list.html"><span class="kw960">std::<span class="me2">initializer_list</span></span></a><span class="sy1">&lt;</span><span class="kw4">int</span><span class="sy1">&gt;</span><span class="sy4">::</span><span class="me2">iterator</span><span class="sy1">&gt;</span>
it <span class="br0">{</span>v.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, <span class="nu0">3</span><span class="br0">}</span><span class="sy4">;</span>
<span class="kw4">constexpr</span> <span class="kw4">auto</span> d1 <span class="sy1">=</span> it <span class="sy2">-</span> std<span class="sy4">::</span><span class="me2">default_sentinel</span><span class="sy4">;</span>
static_assert<span class="br0">(</span> d1 <span class="sy1">==</span> <span class="sy2">-</span><span class="nu0">3</span> <span class="br0">)</span><span class="sy4">;</span> <span class="co1">// (1)</span>
<span class="kw4">constexpr</span> <span class="kw4">auto</span> d2 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">default_sentinel</span> <span class="sy2">-</span> it<span class="sy4">;</span>
static_assert<span class="br0">(</span> d2 <span class="sy1">==</span> <span class="sy2">+</span><span class="nu0">3</span> <span class="br0">)</span><span class="sy4">;</span> <span class="co1">// (2)</span>
<span class="br0">}</span></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-iterator-counted_iterator-operator_arith.html"><span class="t-lines"><span>operator++</span><span>operator++<span class="t-dsc-small">(int)</span></span><span>operator+=</span><span>operator+</span><span>operator--</span><span>operator--<span class="t-dsc-small">(int)</span></span><span>operator-=</span><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>&#25512;&#36827;&#25110;&#22238;&#36864;&#36845;&#20195;&#22120;<br />
<span class="t-mark">(&#20844;&#24320;&#25104;&#21592;&#20989;&#25968;)</span></td>
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<div><a href="cpp-iterator-counted_iterator-operator+.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>&#20196;&#36845;&#20195;&#22120;&#21069;&#36827;<br />
<span class="t-mark">(&#20989;&#25968;&#27169;&#26495;)</span></td>
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<div><a href="cpp-iterator-counted_iterator-operator-.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>&#35745;&#31639;&#20004;&#20010;&#36845;&#20195;&#22120;&#36866;&#37197;&#22120;&#38388;&#30340;&#36317;&#31163;<br />
<span class="t-mark">(&#20989;&#25968;&#27169;&#26495;)</span></td>
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<div><a href="cpp-iterator-default_sentinel_t.html"><span class="t-lines"><span>default_sentinel_t</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>&#29992;&#20110;&#30693;&#26195;&#20854;&#36793;&#30028;&#30340;&#36845;&#20195;&#22120;&#30340;&#40664;&#35748;&#21736;&#20301;<br />
<span class="t-mark">(&#31867;)</span></td>
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