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<h1 id="firstHeading" class="firstHeading"><code>std::basic_string</code> &#30340;&#25512;&#23548;&#25351;&#24341;</h1>
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<div id="contentSub"><span class="subpages">&lt; <a href="cpp.html">cpp</a>&lrm; | <a href="cpp-string.html">string</a>&lrm; | <a href="cpp-string-basic_string.html">basic string</a></span></div>
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<div>&#23450;&#20041;&#20110;&#22836;&#25991;&#20214; <code><a href="cpp-header-string.html">&lt;string&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> InputIt, <span class="kw1">class</span> Alloc <span class="sy1">=</span> <a href="cpp-memory-allocator.html"><span class="kw700">std::<span class="me2">allocator</span></span></a><span class="sy1">&lt;</span><br /></span>
<p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; <span class="kw1">typename</span> <a href="cpp-iterator-iterator_traits.html"><span class="kw651">std::<span class="me2">iterator_traits</span></span></a><span class="sy1">&lt;</span>InputIt<span class="sy1">&gt;</span><span class="sy4">::</span><span class="me2">value_type</span><span class="sy1">&gt;&gt;</span><br />
basic_string<span class="br0">(</span>InputIt, InputIt, Alloc <span class="sy1">=</span> Alloc<span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><br />
<span class="sy2">-</span><span class="sy1">&gt;</span> basic_string<span class="sy1">&lt;</span><span class="kw1">typename</span> <a href="cpp-iterator-iterator_traits.html"><span class="kw651">std::<span class="me2">iterator_traits</span></span></a><span class="sy1">&lt;</span>InputIt<span class="sy1">&gt;</span><span class="sy4">::</span><span class="me2">value_type</span>,<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; <a href="cpp-string-char_traits.html"><span class="kw1267">std::<span class="me2">char_traits</span></span></a><span class="sy1">&lt;</span><span class="kw1">typename</span> <a href="cpp-iterator-iterator_traits.html"><span class="kw651">std::<span class="me2">iterator_traits</span></span></a><span class="sy1">&lt;</span>InputIt<span class="sy1">&gt;</span><span class="sy4">::</span><span class="me2">value_type</span><span class="sy1">&gt;</span>,<br /></p>
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Alloc<span class="sy1">&gt;</span><span class="sy4">;</span></div>
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<td>(1)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></td>
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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> CharT,<br /></span>
<p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<span class="kw1">class</span> Traits,<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<span class="kw1">class</span> Alloc <span class="sy1">=</span> <a href="cpp-memory-allocator.html"><span class="kw700">std::<span class="me2">allocator</span></span></a><span class="sy1">&lt;</span>CharT<span class="sy1">&gt;&gt;</span><br />
<span class="kw1">explicit</span> basic_string<span class="br0">(</span><a href="cpp-string-basic_string_view.html"><span class="kw1246">std::<span class="me2">basic_string_view</span></span></a><span class="sy1">&lt;</span>CharT, Traits<span class="sy1">&gt;</span>, <span class="kw4">const</span> Alloc<span class="sy3">&amp;</span> <span class="sy1">=</span> Alloc<span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><br /></p>
<span class="sy2">-</span><span class="sy1">&gt;</span> basic_string<span class="sy1">&lt;</span>CharT, Traits, Alloc<span class="sy1">&gt;</span><span class="sy4">;</span></div>
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<td>(2)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></td>
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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> CharT,<br /></span>
<p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<span class="kw1">class</span> Traits,<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<span class="kw1">class</span> Alloc <span class="sy1">=</span> <a href="cpp-memory-allocator.html"><span class="kw700">std::<span class="me2">allocator</span></span></a><span class="sy1">&lt;</span>CharT<span class="sy1">&gt;&gt;&gt;</span><br />
basic_string<span class="br0">(</span><a href="cpp-string-basic_string_view.html"><span class="kw1246">std::<span class="me2">basic_string_view</span></span></a><span class="sy1">&lt;</span>CharT, Traits<span class="sy1">&gt;</span>, <span class="kw1">typename</span> <span class="coMULTI">/*see below*/</span><span class="sy4">::</span><span class="me2">size_type</span>,<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<span class="kw1">typename</span> <span class="coMULTI">/*see below*/</span><span class="sy4">::</span><span class="me2">size_type</span>, <span class="kw4">const</span> Alloc<span class="sy3">&amp;</span> <span class="sy1">=</span> Alloc<span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><br /></p>
&nbsp; &nbsp; <span class="sy2">-</span><span class="sy1">&gt;</span> basic_string<span class="sy1">&lt;</span>CharT, Traits, Alloc<span class="sy1">&gt;</span><span class="sy4">;</span></div>
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<td>(3)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></td>
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<div class="t-li1"><span class="t-li">1)</span> &#20026; <span class="t-lc"><a href="cpp-string-basic_string.html">std::basic_string</a></span> &#25552;&#20379;&#27492;<a href="cpp-language-class_template_argument_deduction.html">&#25512;&#23548;&#25351;&#24341;</a>&#65292;&#20197;&#20801;&#35768;&#20174;&#36845;&#20195;&#22120;&#33539;&#22260;&#25512;&#23548;&#12290;&#27492;&#37325;&#36733;&#20165;&#33509; <code>InputIt</code> &#28385;&#36275;<a href="cpp-named_req-InputIterator.html"><span style="font-style:italic">&#32769;&#24335;&#36755;&#20837;&#36845;&#20195;&#22120;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(LegacyInputIterator)</span></a> &#19988; <code>Alloc</code> &#28385;&#36275;<a href="cpp-named_req-Allocator.html"><span style="font-style:italic">&#20998;&#37197;&#22120;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(Allocator)</span></a> &#25165;&#21442;&#19982;&#37325;&#36733;&#20915;&#35758;&#12290;</div>
<div class="t-li1"><span class="t-li">2-3)</span> &#20026; <span class="t-lc"><a href="cpp-string-basic_string.html">std::basic_string</a></span> &#25552;&#20379;&#36825;&#20123;&#25512;&#23548;&#25351;&#24341;&#20197;&#20801;&#35768;&#20174; <span class="t-lc"><a href="cpp-string-basic_string_view.html">std::basic_string_view</a></span> &#25512;&#23548;&#12290; <span class="t-v">(3)</span> &#20013;&#30340;<span class="t-c"><span class="mw-geshi cpp source-cpp">size_type</span></span> &#21442;&#25968;&#25351;&#20195;&#25512;&#23548;&#25351;&#24341;&#25152;&#25512;&#20986;&#31867;&#22411;&#30340; <span class="t-c"><span class="mw-geshi cpp source-cpp">size_type</span></span> &#25104;&#21592;&#31867;&#22411;&#12290;&#36825;&#20123;&#37325;&#36733;&#20165;&#33509; <code>Alloc</code> &#28385;&#36275;<a href="cpp-named_req-Allocator.html"><span style="font-style:italic">&#20998;&#37197;&#22120;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(Allocator)</span></a> &#25165;&#21442;&#19982;&#37325;&#36733;&#20915;&#35758;&#12290;</div>
<p>&#27880;&#24847;&#65306;&#24211;&#30830;&#23450;&#31867;&#22411;&#26159;&#21542;&#28385;&#36275;<a href="cpp-named_req-InputIterator.html"><span style="font-style:italic">&#32769;&#24335;&#36755;&#20837;&#36845;&#20195;&#22120;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(LegacyInputIterator)</span></a> &#30340;&#31243;&#24230;&#26159;&#26410;&#25351;&#23450;&#30340;&#65292;&#38500;&#20102;&#26368;&#20302;&#35201;&#27714;&#26159;&#25972;&#25968;&#31867;&#22411;&#19981;&#20855;&#22791;&#36755;&#20837;&#36845;&#20195;&#22120;&#30340;&#26465;&#20214;&#12290;&#31867;&#20284;&#22320;&#65292;&#30830;&#23450;&#31867;&#22411;&#26159;&#21542;&#28385;&#36275;<a href="cpp-named_req-Allocator.html"><span style="font-style:italic">&#20998;&#37197;&#22120;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(Allocator)</span></a> &#26159;&#26410;&#25351;&#23450;&#30340;&#65292;&#38500;&#20102;&#26368;&#20302;&#35201;&#27714;&#26159;&#25104;&#21592;&#31867;&#22411; <code>Alloc::value_type</code> &#24517;&#39035;&#23384;&#22312;&#65292;&#19988;&#34920;&#36798;&#24335; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-utility-declval.html"><span class="kw1120">std::<span class="me2">declval</span></span></a><span class="sy1">&lt;</span>Alloc<span class="sy3">&amp;</span><span class="sy1">&gt;</span><span class="br0">(</span><span class="br0">)</span>.<span class="me1">allocate</span><span class="br0">(</span><a href="cpp-types-size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a><span class="br0">{</span><span class="br0">}</span><span class="br0">)</span></span></span> &#22312;&#20316;&#20026;&#19981;&#27714;&#20540;&#25805;&#20316;&#25968;&#26102;&#24517;&#39035;&#20026;&#33391;&#26500;&#12290;</p>
<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">&#27880;&#35299;</span></h3>
<p>&#38656;&#35201;&#25351;&#24341; <span class="t-v">(2-3)</span> &#65292;&#22240;&#20026; <span class="t-lc"><a href="cpp-string-basic_string.html">std::basic_string</a></span> &#23545;&#20110; <span class="t-lc"><a href="cpp-string-basic_string_view.html">std::basic_string_view</a></span> &#30340;&#26500;&#36896;&#20989;&#25968;&#34987;&#35774;&#20026;&#27169;&#26495;&#65292;&#20197;&#36991;&#20813;&#26082;&#23384;&#20195;&#30721;&#20013;&#30340;&#27495;&#20041;&#65292;&#32780;&#36825;&#20123;&#27169;&#26495;&#19981;&#25903;&#25345;&#31867;&#27169;&#26495;&#23454;&#21442;&#25512;&#23548;&#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;string&gt;</span>
<span class="co2">#include &lt;vector&gt;</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">char</span><span class="sy1">&gt;</span> v <span class="sy1">=</span> <span class="br0">{</span><span class="st0">&#39;a&#39;</span>, <span class="st0">&#39;b&#39;</span>, <span class="st0">&#39;c&#39;</span><span class="br0">}</span><span class="sy4">;</span>
<a href="cpp-string-basic_string.html"><span class="kw1228">std::<span class="me2">basic_string</span></span></a> s<span class="br0">(</span>v.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, v.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// &#20351;&#29992;&#26174;&#24335;&#25512;&#23548;&#25351;&#24341;</span>
<span class="br0">}</span></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>
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<th>DR</th>
<th>&#24212;&#29992;&#20110;</th>
<th>&#20986;&#29256;&#26102;&#30340;&#34892;&#20026;</th>
<th>&#27491;&#30830;&#34892;&#20026;</th>
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<td><a rel="nofollow" class="external text" href="https://cplusplus.github.io/LWG/issue3075">LWG 3075</a></td>
<td>C++17</td>
<td>&#19981;&#25903;&#25345;&#20174; <code>basic_string_view</code> &#25512;&#23548;&#65288;&#20026; <a rel="nofollow" class="external text" href="https://cplusplus.github.io/LWG/issue2946">LWG &#38382;&#39064; 2946</a> &#25152;&#24694;&#21270;&#65289;</td>
<td>&#28155;&#21152;&#25512;&#23548;&#25351;&#24341;</td>
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