562 lines
43 KiB
HTML
562 lines
43 KiB
HTML
<!DOCTYPE html>
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<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
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<title>std::chrono::parse</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_chrono_parse skin-cppreference2 action-view cpp-navbar">
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::chrono::</span>parse</h1>
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<div id="bodyContent">
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-chrono.html">chrono</a></span></div>
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<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
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<table class="t-dcl-begin">
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<tbody>
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<td>
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<div>定义于头文件 <code><a href="cpp-header-chrono.html"><chrono></a></code></div>
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</td>
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<td></td>
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<td></td>
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<tr class="t-dcl t-since-cxx20">
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<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> CharT, <span class="kw1">class</span> Parsable <span class="sy1">></span><br />
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<span class="coMULTI">/* unspecified */</span> parse<span class="br0">(</span> <span class="kw4">const</span> CharT<span class="sy2">*</span> fmt, Parsable<span class="sy3">&</span> tp <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(1)</td>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx20">
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<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> CharT, <span class="kw1">class</span> Traits, <span class="kw1">class</span> Alloc, <span class="kw1">class</span> Parsable <span class="sy1">></span><br /></span>
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<p><span class="coMULTI">/* unspecified */</span> parse<span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-string-basic_string.html"><span class="kw1228">std::<span class="me2">basic_string</span></span></a><span class="sy1"><</span>CharT, Traits, Alloc<span class="sy1">></span><span class="sy3">&</span> fmt,<br /></p>
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Parsable<span class="sy3">&</span> tp <span class="br0">)</span><span class="sy4">;</span></div>
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</td>
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<td>(2)</td>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx20">
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<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> CharT, <span class="kw1">class</span> Traits, <span class="kw1">class</span> Alloc, <span class="kw1">class</span> Parsable <span class="sy1">></span><br /></span>
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<p><span class="coMULTI">/* unspecified */</span> parse<span class="br0">(</span> <span class="kw4">const</span> CharT<span class="sy2">*</span> fmt, Parsable<span class="sy3">&</span> tp,<br /></p>
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<a href="cpp-string-basic_string.html"><span class="kw1228">std::<span class="me2">basic_string</span></span></a><span class="sy1"><</span>CharT, Traits, Alloc<span class="sy1">></span><span class="sy3">&</span> abbrev <span class="br0">)</span><span class="sy4">;</span></div>
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</td>
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<td>(3)</td>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx20">
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<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> CharT, <span class="kw1">class</span> Traits, <span class="kw1">class</span> Alloc, <span class="kw1">class</span> Parsable <span class="sy1">></span><br /></span>
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<p><span class="coMULTI">/* unspecified */</span> parse<span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-string-basic_string.html"><span class="kw1228">std::<span class="me2">basic_string</span></span></a><span class="sy1"><</span>CharT, Traits, Alloc<span class="sy1">></span><span class="sy3">&</span> fmt,<br />
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Parsable<span class="sy3">&</span> tp,<br /></p>
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<a href="cpp-string-basic_string.html"><span class="kw1228">std::<span class="me2">basic_string</span></span></a><span class="sy1"><</span>CharT, Traits, Alloc<span class="sy1">></span><span class="sy3">&</span> abbrev <span class="br0">)</span><span class="sy4">;</span></div>
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</td>
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<td>(4)</td>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx20">
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<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> CharT, <span class="kw1">class</span> Parsable <span class="sy1">></span><br /></span>
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<p><span class="coMULTI">/* unspecified */</span> parse<span class="br0">(</span> <span class="kw4">const</span> CharT<span class="sy2">*</span> fmt, Parsable<span class="sy3">&</span> tp,<br /></p>
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<a href="cpp-chrono-duration.html"><span class="kw998">std::<span class="me2">chrono</span><span class="sy4">::</span><span class="me2">minutes</span></span></a><span class="sy3">&</span> offset <span class="br0">)</span><span class="sy4">;</span></div>
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</td>
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<td>(5)</td>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx20">
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<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> CharT, <span class="kw1">class</span> Traits, <span class="kw1">class</span> Alloc, <span class="kw1">class</span> Parsable <span class="sy1">></span><br /></span>
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<p><span class="coMULTI">/* unspecified */</span> parse<span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-string-basic_string.html"><span class="kw1228">std::<span class="me2">basic_string</span></span></a><span class="sy1"><</span>CharT, Traits, Alloc<span class="sy1">></span><span class="sy3">&</span> fmt,<br /></p>
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Parsable<span class="sy3">&</span> tp, <a href="cpp-chrono-duration.html"><span class="kw998">std::<span class="me2">chrono</span><span class="sy4">::</span><span class="me2">minutes</span></span></a><span class="sy3">&</span> offset <span class="br0">)</span><span class="sy4">;</span></div>
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</td>
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<td>(6)</td>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx20">
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<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> CharT, <span class="kw1">class</span> Traits, <span class="kw1">class</span> Alloc, <span class="kw1">class</span> Parsable <span class="sy1">></span><br /></span>
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<p><span class="coMULTI">/* unspecified */</span> parse<span class="br0">(</span> <span class="kw4">const</span> CharT<span class="sy2">*</span> fmt, Parsable<span class="sy3">&</span> tp,<br />
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<a href="cpp-string-basic_string.html"><span class="kw1228">std::<span class="me2">basic_string</span></span></a><span class="sy1"><</span>CharT, Traits, Alloc<span class="sy1">></span><span class="sy3">&</span> abbrev,<br /></p>
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<a href="cpp-chrono-duration.html"><span class="kw998">std::<span class="me2">chrono</span><span class="sy4">::</span><span class="me2">minutes</span></span></a><span class="sy3">&</span> offset <span class="br0">)</span><span class="sy4">;</span></div>
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</td>
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<td>(7)</td>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx20">
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<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> CharT, <span class="kw1">class</span> Traits, <span class="kw1">class</span> Alloc, <span class="kw1">class</span> Parsable <span class="sy1">></span><br /></span>
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<p><span class="coMULTI">/* unspecified */</span> parse<span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-string-basic_string.html"><span class="kw1228">std::<span class="me2">basic_string</span></span></a><span class="sy1"><</span>CharT, Traits, Alloc<span class="sy1">></span><span class="sy3">&</span> fmt,<br />
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Parsable<span class="sy3">&</span> tp,<br />
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<a href="cpp-string-basic_string.html"><span class="kw1228">std::<span class="me2">basic_string</span></span></a><span class="sy1"><</span>CharT, Traits, Alloc<span class="sy1">></span><span class="sy3">&</span> abbrev,<br /></p>
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<a href="cpp-chrono-duration.html"><span class="kw998">std::<span class="me2">chrono</span><span class="sy4">::</span><span class="me2">minutes</span></span></a><span class="sy3">&</span> offset <span class="br0">)</span><span class="sy4">;</span></div>
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</td>
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<td>(8)</td>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
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</tr>
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<tr class="t-dcl-sep">
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<td></td>
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<td></td>
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<td></td>
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</tr>
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</tbody>
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</table>
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<p>返回未指定类型的对象 <code>manip</code> ，使得给定 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-io-basic_istream.html"><span class="kw1713">std::<span class="me2">basic_istream</span></span></a><span class="sy1"><</span>CharT, Traits<span class="sy1">></span></span></span> 对象 <code>is</code> ，表达式 <span class="t-c"><span class="mw-geshi cpp source-cpp">is <span class="sy1">>></span> manip</span></span> 以下列方式调用 <code>from_stream</code> （无限定，以启用<a href="cpp-language-adl.html">实参依赖查找</a>）：</p>
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<div class="t-li1"><span class="t-li">1)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp">from_stream<span class="br0">(</span>is, fmt, tp<span class="br0">)</span></span></span></div>
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<div class="t-li1"><span class="t-li">2)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp">from_stream<span class="br0">(</span>is, fmt.<span class="me1">c_str</span><span class="br0">(</span><span class="br0">)</span>, tp<span class="br0">)</span></span></span></div>
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<div class="t-li1"><span class="t-li">3)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp">from_stream<span class="br0">(</span>is, fmt, tp, <a href="cpp-memory-addressof.html"><span class="kw757">std::<span class="me2">addressof</span></span></a><span class="br0">(</span>abbrev<span class="br0">)</span><span class="br0">)</span></span></span></div>
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<div class="t-li1"><span class="t-li">4)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp">from_stream<span class="br0">(</span>is, fmt.<span class="me1">c_str</span><span class="br0">(</span><span class="br0">)</span>, tp, <a href="cpp-memory-addressof.html"><span class="kw757">std::<span class="me2">addressof</span></span></a><span class="br0">(</span>abbrev<span class="br0">)</span><span class="br0">)</span></span></span></div>
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<div class="t-li1"><span class="t-li">5)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp">from_stream<span class="br0">(</span>is, fmt, tp,<br />
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<span class="kw1">static_cast</span><span class="sy1"><</span><a href="cpp-string-basic_string.html"><span class="kw1228">std::<span class="me2">basic_string</span></span></a><span class="sy1"><</span>CharT, Traits, Alloc<span class="sy1">></span><span class="sy2">*</span><span class="sy1">></span><span class="br0">(</span>nullptr<span class="br0">)</span>, <span class="sy3">&</span>offset<span class="br0">)</span></span></span></div>
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<div class="t-li1"><span class="t-li">6)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp">from_stream<span class="br0">(</span>is, fmt.<span class="me1">c_str</span><span class="br0">(</span><span class="br0">)</span>, tp,<br />
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<span class="kw1">static_cast</span><span class="sy1"><</span><a href="cpp-string-basic_string.html"><span class="kw1228">std::<span class="me2">basic_string</span></span></a><span class="sy1"><</span>CharT, Traits, Alloc<span class="sy1">></span><span class="sy2">*</span><span class="sy1">></span><span class="br0">(</span>nullptr<span class="br0">)</span>, <span class="sy3">&</span>offset<span class="br0">)</span></span></span></div>
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<div class="t-li1"><span class="t-li">7)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp">from_stream<span class="br0">(</span>is, fmt, tp, <a href="cpp-memory-addressof.html"><span class="kw757">std::<span class="me2">addressof</span></span></a><span class="br0">(</span>abbrev<span class="br0">)</span>, <span class="sy3">&</span>offset<span class="br0">)</span></span></span></div>
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<div class="t-li1"><span class="t-li">8)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp">from_stream<span class="br0">(</span>is, fmt.<span class="me1">c_str</span><span class="br0">(</span><span class="br0">)</span>, tp, <a href="cpp-memory-addressof.html"><span class="kw757">std::<span class="me2">addressof</span></span></a><span class="br0">(</span>abbrev<span class="br0">)</span>, <span class="sy3">&</span>offset<span class="br0">)</span></span></span> 。</div>
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<p>表达式 <span class="t-c"><span class="mw-geshi cpp source-cpp">is <span class="sy1">>></span> manip</span></span> 是 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-io-basic_istream.html"><span class="kw1713">std::<span class="me2">basic_istream</span></span></a><span class="sy1"><</span>CharT, Traits<span class="sy1">></span></span></span> 类型左值，其值为 <code>is</code> 。</p>
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<p>这些重载仅若对应的 <code>from_stream</code> 表达式为良构才参与重载决议。</p>
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<p>推荐实现令使用到格式字符串的悬垂引用困难，例如通过令返回类型不可移动并阻止 <span class="t-c"><span class="mw-geshi cpp source-cpp">operator<span class="sy1">>></span></span></span> 接受返回类型的左值。</p>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
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<table class="t-par-begin">
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<tr class="t-par">
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<td>fmt</td>
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<td>-</td>
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<td>格式字符串（见后述）</td>
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</tr>
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<tr class="t-par">
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<td>tp</td>
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<td>-</td>
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<td>保有分析结果的对象</td>
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</tr>
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<tr class="t-par">
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<td>abbrev</td>
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<td>-</td>
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<td>保有对应 <code>%Z</code> 说明符的时区缩写或名称的字符串</td>
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</tr>
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<tr class="t-par">
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<td>offset</td>
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<td>-</td>
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<td>表示对应 <code>%z</code> 说明符的距 UTC 偏移的时长</td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E6.A0.BC.E5.BC.8F.E5.AD.97.E7.AC.A6.E4.B8.B2">格式字符串</span></h3>
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<p>格式字符串由零或更多个转换说明符和通常字符组成。每个通常字符，除了空白字符和空终止字符，都匹配一个来自输入流的等同字符，或若流上的下个字符不比较相等则导致函数失败。</p>
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<p>每个空白字符匹配输入流中的零或更多个空白字符。</p>
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<p>每个不修饰的转换说明符以 <code>%</code> 字符后随一个确定说明符行为的字符开始。某些转换说明符拥有在 <code>%</code> 字符后插入修饰字符 <code>E</code> 或 <code>O</code> 的修饰形式。某些转换说明符拥有在 <code>%</code> 字符后插入作为十进制整数（下面显示为 <i><code>N</code></i> ）的宽度参数的修饰形式。每个转换说明符导致匹配的字符被按照下表转译成时间和日期类型的部分。</p>
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<p>格式字符串中，以 <code>%</code> 开始但不匹配下列转换说明符之一的字符序列被转译成通常字符。</p>
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<p>若 <code>from_stream</code> 无法分析格式字符串所指定的每项内容，或若分析出的信息不足以指定完整结果，或若分析透露矛盾的信息，则调用 <span class="t-c"><span class="mw-geshi cpp source-cpp">is.<span class="me1">setstate</span><span class="br0">(</span><a href="cpp-io-ios_base-iostate.html"><span class="kw1700">std::<span class="me2">ios_base</span><span class="sy4">::</span><span class="me2">failbit</span></span></a><span class="br0">)</span></span></span> 。</p>
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<p>下列转换说明符可用：</p>
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<table class="wikitable" style="font-size:85%; max-width:90em;">
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<tr>
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<th>转换<br />
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说明符</th>
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<th>解释</th>
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</tr>
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<tr>
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<th><code>%%</code></th>
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<td>匹配字面的 <code>%</code> 字符。</td>
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</tr>
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<tr>
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<th><code>%n</code></th>
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<td>匹配一个空白字符。</td>
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</tr>
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<tr>
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<th><code>%t</code></th>
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<td>匹配零或一个空白字符。</td>
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</tr>
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<tr>
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<th colspan="3">年</th>
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</tr>
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<tr>
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<th><code>%C</code><br />
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<code>%<i>N</i>C</code><br />
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<code>%EC</code><br />
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<code>%OC</code></th>
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<td>将世纪分析成十进制数。宽度 <i>N</i> 指定要读取的最大字符数。默认宽度为 2 。容许但不要求前导零。
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<p>修饰的命令 <code>%EC</code> 和 <code>%OC</code> 转译本地环境的替用世纪表示。</p>
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</td>
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</tr>
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<tr>
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<th><code>%y</code><br />
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<code>%<i>N</i>y</code><br />
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<code>%Ey</code><br />
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<code>%Oy</code></th>
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<td>分析年的低二位十进制位。若不另外指定世纪（例如用 %C ），则预设范围 [69, 99] 中的值指代 1969 至 1999 年，<br />
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而预设范围 [00, 68] 中的值指代 2000 至 2068 年。宽度 <i>N</i> 指定要读取的最大字符数。默认宽度为 2 。容许但不要求前导零。
|
|
<p>修饰的命令 <code>%Ey</code> 和 <code>%Oy</code> 转译本地环境的替用表示。</p>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%Y</code><br />
|
|
<code>%<i>N</i>Y</code><br />
|
|
<code>%EY</code></th>
|
|
<td>将年分析成十进制数。宽度 <i>N</i> 指定要读取的最大字符数。默认宽度为 4 。容许但不要求前导零。
|
|
<p>修饰的命令 <code>%EY</code> 转译本地环境的替用表示。</p>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<th colspan="3">月</th>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%b</code><br />
|
|
<code>%B</code><br />
|
|
<code>%h</code></th>
|
|
<td>分析本地环境的完整或缩写的无关大小写的月名。</td>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%m</code><br />
|
|
<code>%<i>N</i>m</code><br />
|
|
<code>%Om</code></th>
|
|
<td>将月份分析成十进制数（一月为 <code>1</code> ）。宽度 <i>N</i> 指定要读取的最大字符数。默认宽度为 2 。容许但不要求前导零。
|
|
<p>修饰的命令 <code>%Om</code> 转译本地环境的替用表示。</p>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<th colspan="3">日</th>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%d</code><br />
|
|
<code>%<i>N</i>d</code><br />
|
|
<code>%Od</code><br />
|
|
<code>%e</code><br />
|
|
<code>%<i>N</i>e</code><br />
|
|
<code>%Oe</code></th>
|
|
<td>将月之日分析成十进制数。宽度 <i>N</i> 指定要读取的最大字符数。默认宽度为 2 。容许但不要求前导零。
|
|
<p>修改的命令 <code>%Od</code> 和 <code>%Oe</code> 转译本地环境的替用表示。</p>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<th colspan="3">星期之日</th>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%a</code><br />
|
|
<code>%A</code></th>
|
|
<td>分析本地环境的完整或缩写的无关大小写的星期之日名。</td>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%u</code><br />
|
|
<code>%<i>N</i>u</code><br />
|
|
<code>%Ou</code></th>
|
|
<td>分析 ISO 星期之日为十进制数 (1-7) ，其中星期一为 <code>1</code> 。宽度 <i>N</i> 指定要读取的最大字符数。默认宽度为 1 。容许但不要求前导零。
|
|
<p>修饰的命令 <code>%Ou</code> 转译本地环境的替用表示。</p>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%w</code><br />
|
|
<code>%<i>N</i>w</code><br />
|
|
<code>%Ow</code></th>
|
|
<td>分析星期之日为十进制数 (0-6) ，其中星期日为 <code>0</code> 。宽度 <i>N</i> 指定要读取的最大字符数。默认宽度为 1 。容许但不要求前导零。
|
|
<p>修饰的命令 <code>%Ow</code> 转译本地环境的替用表示。</p>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<th colspan="3">基于 ISO 8601 星期的年</th>
|
|
</tr>
|
|
<tr>
|
|
<td colspan="3">
|
|
<p>ISO 8601 中，星期始于星期一，而每年的首周必须满足下列要求：</p>
|
|
<ul>
|
|
<li>包含 1 月 4 日</li>
|
|
<li>包含该年的首个星期四</li>
|
|
</ul>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%g</code><br />
|
|
<code>%<i>N</i>g</code></th>
|
|
<td>分析基于 ISO 8601 的年的低二位十进制数。宽度 <i>N</i> 指定要读取的最大字符数。默认宽度为 2 。容许但不要求前导零。</td>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%G</code><br />
|
|
<code>%<i>N</i>G</code></th>
|
|
<td>将基于 ISO 8601 的年分析成十进制数。宽度 <i>N</i> 指定要读取的最大字符数。默认宽度为 4 。容许但不要求前导零。</td>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%V</code><br />
|
|
<code>%<i>N</i>V</code></th>
|
|
<td>将基于 ISO 8601 的年之星期分析成十进制数。宽度 <i>N</i> 指定要读取的最大字符数。默认宽度为 2 。容许但不要求前导零。</td>
|
|
</tr>
|
|
<tr>
|
|
<th colspan="3">年之星期/日</th>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%j</code><br />
|
|
<code>%<i>N</i>j</code></th>
|
|
<td>分析年之日为十进制数（ 1 月 1 日为 <code>1</code> ）。宽度 <i>N</i> 指定要读取的最大字符数。默认宽度为 3 。容许但不要求前导零。</td>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%U</code><br />
|
|
<code>%<i>N</i>U</code></th>
|
|
<td>分析年之星期为十进制数。该年的首个星期日是星期 01 的首日。同年中先于该天的日期属于星期 00 。<br />
|
|
宽度 <i>N</i> 指定要读取的最大字符数。默认宽度为 2 。容许但不要求前导零。</td>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%W</code><br />
|
|
<code>%<i>N</i>W</code></th>
|
|
<td>分析年之星期为十进制数。该年的首个星期一是星期 01 的首日。同年中先于该天的日期属于星期 00 。<br />
|
|
宽度 <i>N</i> 指定要读取的最大字符数。默认宽度为 2 。容许但不要求前导零。</td>
|
|
</tr>
|
|
<tr>
|
|
<th colspan="3">日期</th>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%D</code></th>
|
|
<td>等价于 <code><b>"%m/%d/%y"</b></code> 。</td>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%F</code><br />
|
|
<code>%<i>N</i>F</code></th>
|
|
<td>等价于 <code><b>"%Y-%m-%d"</b></code> 。若指定宽度，则它只应用于 <code>%Y</code> 。</td>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%x</code><br />
|
|
<code>%Ex</code></th>
|
|
<td>分析本地环境的日期表示。
|
|
<p>修饰的命令 <code>%Ex</code> 转译本地环境的替用日期表示。</p>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<th colspan="3">当天时刻</th>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%H</code><br />
|
|
<code>%<i>N</i>H</code><br />
|
|
<code>%OH</code></th>
|
|
<td>将时（ 24 小时时钟）分析成十进制数。宽度 <i>N</i> 指定要读取的最大字符数。默认宽度为 2 。容许但不要求前导零。
|
|
<p>修饰的命令 <code>%OH</code> 转译本地环境的替用表示。</p>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%I</code><br />
|
|
<code>%<i>N</i>I</code></th>
|
|
<td>将时（ 12 小时时钟）分析成十进制数。宽度 <i>N</i> 指定要读取的最大字符数。默认宽度为 2 。容许但不要求前导零。</td>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%M</code><br />
|
|
<code>%<i>N</i>M</code><br />
|
|
<code>%OM</code></th>
|
|
<td>将分分析成十进制数。宽度 <i>N</i> 指定要读取的最大字符数。默认宽度为 2 。容许但不要求前导零。
|
|
<p>修饰的命令 <code>%OM</code> 转译本地环境的替用表示。</p>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%S</code><br />
|
|
<code>%<i>N</i>S</code><br />
|
|
<code>%OS</code></th>
|
|
<td>将秒分析成十进制数。宽度 <i>N</i> 指定要读取的最大字符数。默认宽度为 2 。容许但不要求前导零。
|
|
<p>修饰的命令 <code>%OS</code> 转译本地环境的替用表示。</p>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%p</code></th>
|
|
<td>分析与 12 小时时钟关联的 AM/PM 记法的本地环境等价版本。</td>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%R</code></th>
|
|
<td>等价于 <code><b>"%H:%M"</b></code> 。</td>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%T</code></th>
|
|
<td>等价于 <code><b>"%H:%M:%S"</b></code> 。</td>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%r</code></th>
|
|
<td>分析本地环境的 12 小时时钟时刻。</td>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%X</code><br />
|
|
<code>%EX</code></th>
|
|
<td>分析本地环境的时刻表示。
|
|
<p>修饰的命令 <code>%EX</code> 转译本地环境的替用时间表示。</p>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<th colspan="3">杂项</th>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%c</code><br />
|
|
<code>%Ec</code></th>
|
|
<td>分析本地环境的日期和时间表示。
|
|
<p>修饰的命令 <code>%Ec</code> 转译本地环境的替用日期和时间表示。</p>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%z</code><br />
|
|
<code>%Ez</code><br />
|
|
<code>%Oz</code></th>
|
|
<td>以格式 <code>[+|-]hh[mm]</code> 分析距 UTC 的偏移。例如 <code>-0430</code> 指代落后 UTC 4 小时 30 分，而 <code>04</code> 指代领先 UTC 4 小时。
|
|
<p>修饰的命令 <code>%Ez</code> 和 <code>%Oz</code> 分析格式 <code>[+|-]h[h][:mm]</code> （即要求时和分之间有 <code>:</code> ，并令时的前导零可选）。</p>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<th><code>%Z</code></th>
|
|
<td>分析时区缩写或名称，取仅含字符 <code>A</code> 到 <code>Z</code> 、 <code>a</code> 到 <code>z</code> 、 <code>0</code> 到 <code>9</code> 、 <code>-</code> 、 <code>+</code> 、 <code>_</code> 和 <code>/</code> 的最长字符序列。</td>
|
|
</tr>
|
|
</table>
|
|
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
|
|
<table class="metadata plainlinks ambox mbox-small-left ambox-notice" style="">
|
|
<tr>
|
|
<td class="mbox-empty-cell"></td>
|
|
<td class="mbox-text" style="">本节未完成<br />
|
|
原因：暂无示例</td>
|
|
</tr>
|
|
</table>
|
|
<h3><span class="mw-headline" id=".E7.BC.BA.E9.99.B7.E6.8A.A5.E5.91.8A">缺陷报告</span></h3>
|
|
<p>下列更改行为的缺陷报告追溯地应用于以前出版的 C++ 标准。</p>
|
|
<table class="dsctable" style="font-size:0.8em">
|
|
<tr>
|
|
<th>DR</th>
|
|
<th>应用于</th>
|
|
<th>出版时的行为</th>
|
|
<th>正确行为</th>
|
|
</tr>
|
|
<tr>
|
|
<td><a rel="nofollow" class="external text" href="https://cplusplus.github.io/LWG/issue3554">LWG 3554</a></td>
|
|
<td>C++20</td>
|
|
<td>缺少接受简单的空终止字符类型序列的重载</td>
|
|
<td>已添加</td>
|
|
</tr>
|
|
</table>
|
|
<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
|
|
<table class="t-dsc-begin">
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-chrono-system_clock-from_stream.html"><span class="t-lines"><span>from_stream<span class="t-dsc-small">(std::chrono::sys_time)</span></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>按照给定的格式从流分析 sys_time<br />
|
|
<span class="t-mark">(函数模板)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-chrono-utc_clock-from_stream.html"><span class="t-lines"><span>from_stream<span class="t-dsc-small">(std::chrono::utc_time)</span></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>按照给定的格式从流分析 utc_time<br />
|
|
<span class="t-mark">(函数模板)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-chrono-tai_clock-from_stream.html"><span class="t-lines"><span>from_stream<span class="t-dsc-small">(std::chrono::tai_time)</span></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>按照给定的格式从流分析 tai_time<br />
|
|
<span class="t-mark">(函数模板)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-chrono-gps_clock-from_stream.html"><span class="t-lines"><span>from_stream<span class="t-dsc-small">(std::chrono::gps_time)</span></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>按照给定的格式从流分析 gps_time<br />
|
|
<span class="t-mark">(函数模板)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-chrono-file_clock-from_stream.html"><span class="t-lines"><span>from_stream<span class="t-dsc-small">(std::chrono::file_time)</span></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>按照给定的格式从流分析 file_time<br />
|
|
<span class="t-mark">(函数模板)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-chrono-local_t-from_stream.html"><span class="t-lines"><span>from_stream<span class="t-dsc-small">(std::chrono::local_time)</span></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>按照给定的格式从流分析 local_time<br />
|
|
<span class="t-mark">(函数模板)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-chrono-year-from_stream.html"><span class="t-lines"><span>from_stream</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>按照提供的格式从流分析 <code>year</code><br />
|
|
<span class="t-mark">(函数模板)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-chrono-month-from_stream.html"><span class="t-lines"><span>from_stream</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>按照提供的格式从流分析 <code>month</code><br />
|
|
<span class="t-mark">(函数模板)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
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<div><a href="cpp-chrono-day-from_stream.html"><span class="t-lines"><span>from_stream</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
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</div>
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</td>
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<td>按照提供的格式从流分析 <code>day</code><br />
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<span class="t-mark">(函数模板)</span></td>
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</tr>
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-chrono-weekday-from_stream.html"><span class="t-lines"><span>from_stream</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
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</div>
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</td>
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<td>按照提供的格式从流分析 <code>weekday</code><br />
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<span class="t-mark">(函数模板)</span></td>
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</tr>
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-chrono-month_day-from_stream.html"><span class="t-lines"><span>from_stream</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
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</div>
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</td>
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<td>按照提供的格式从流分析 <code>month_day</code><br />
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<span class="t-mark">(函数模板)</span></td>
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</tr>
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-chrono-year_month-from_stream.html"><span class="t-lines"><span>from_stream</span></span></a></div>
|
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
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</div>
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</td>
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<td>按照提供的格式从流分析 <code>year_month</code><br />
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<span class="t-mark">(函数模板)</span></td>
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</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-chrono-year_month_day-from_stream.html"><span class="t-lines"><span>from_stream</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>
|
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<td>按照给定的格式从流分析 <code>year_month_day</code><br />
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<span class="t-mark">(函数模板)</span></td>
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</tr>
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</table>
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</div>
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<div class="visualClear"></div>
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</div>
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</div>
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</div>
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