165 lines
11 KiB
HTML
165 lines
11 KiB
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::source_location</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_utility_source_location 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::</span>source_location</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-utility.html">utility</a></span></div>
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<div>定义于头文件 <code><a href="cpp-header-source_location.html"><source_location></a></code></div>
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<td></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">struct</span> source_location<span class="sy4">;</span></span></div>
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<td class="t-dcl-nopad"></td>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
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<p><code>source_location</code> 类表示关于源码的具体信息,例如文件名、行号以及函数名。以前,希望获得关于调用位置的信息(用于记录、测试或调试目的)的函数必须使用宏,以令如 <span class="t-lc">__LINE__</span> 与 <span class="t-lc">__FILE__</span> 的预定义宏于调用方的环境展开。 <code>source_location</code> 类提供更好的替代。</p>
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<p><code>source_location</code> 符合<a href="cpp-named_req-DefaultConstructible.html"><span style="font-style:italic">可默认构造</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(DefaultConstructible)</span></a> 、<a href="cpp-named_req-CopyConstructible.html"><span style="font-style:italic">可复制构造</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(CopyConstructible)</span></a> 、<a href="cpp-named_req-CopyAssignable.html"><span style="font-style:italic">可复制赋值</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(CopyAssignable)</span></a> 及<a href="cpp-named_req-Destructible.html"><span style="font-style:italic">可析构</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(Destructible)</span></a> 要求。 <code>source_location</code> 的左值符合<a href="cpp-named_req-Swappable.html"><span style="font-style:italic">可交换</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(Swappable)</span></a> 要求。 另外,下列条件为 <code>true</code> :</p>
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<ul>
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<li><span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_move_constructible.html"><span class="kw543">std::<span class="me2">is_nothrow_move_constructible_v</span></span></a><span class="sy1"><</span>std<span class="sy4">::</span><span class="me2">source_location</span><span class="sy1">></span></span></span> 、</li>
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<li><span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_move_assignable.html"><span class="kw561">std::<span class="me2">is_nothrow_move_assignable_v</span></span></a><span class="sy1"><</span>std<span class="sy4">::</span><span class="me2">source_location</span><span class="sy1">></span></span></span> 及</li>
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<li><span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_swappable.html"><span class="kw577">std::<span class="me2">is_nothrow_swappable_v</span></span></a><span class="sy1"><</span>std<span class="sy4">::</span><span class="me2">source_location</span><span class="sy1">></span></span></span> 。</li>
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</ul>
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<p>有意令 <code>source_location</code> 拥有较小的大小并且能高效复制。</p>
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<p><code>source_location</code> 的复制/移动构造函数与复制/移动赋值运算符是否为平凡和/或 constexpr 是未指明的。</p>
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<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E5.87.BD.E6.95.B0">成员函数</span></h3>
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<table class="t-dsc-begin">
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<h5><span class="mw-headline" id=".E5.88.9B.E5.BB.BA">创建</span></h5>
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<div class="t-dsc-member-div t-dsc-member-nobold-div">
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<div><a href="cpp-utility-source_location-source_location.html"><span class="t-lines"><span>(构造函数)</span></span></a></div>
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</div>
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</td>
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<td>构造拥有实现定义的值的新 <code>source_location</code><br />
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<span class="t-mark">(公开成员函数)</span></td>
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<tr class="t-dsc">
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<div class="t-dsc-member-div">
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<div><a href="cpp-utility-source_location-current.html"><span class="t-lines"><span>current</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-cmark">[静态]</span></span></span></div>
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</div>
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</td>
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<td>构造对应调用点位置的新 <code>source_location</code><br />
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<span class="t-mark">(公开静态成员函数)</span></td>
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<h5><span class="mw-headline" id=".E5.9F.9F.E8.AE.BF.E9.97.AE">域访问</span></h5>
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<div class="t-dsc-member-div">
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<div><a href="cpp-utility-source_location-line.html"><span class="t-lines"><span>line</span></span></a></div>
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</td>
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<td>返回此对象所表示的行号<br />
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<span class="t-mark">(公开成员函数)</span></td>
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</tr>
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<tr class="t-dsc">
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<div><a href="cpp-utility-source_location-column.html"><span class="t-lines"><span>column</span></span></a></div>
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</div>
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</td>
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<td>返回此对象所表示的列号<br />
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<span class="t-mark">(公开成员函数)</span></td>
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</tr>
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<tr class="t-dsc">
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<div class="t-dsc-member-div">
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<div><a href="cpp-utility-source_location-file_name.html"><span class="t-lines"><span>file_name</span></span></a></div>
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</div>
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</td>
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<td>返回此对象所表示的文件名<br />
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<span class="t-mark">(公开成员函数)</span></td>
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</tr>
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<tr class="t-dsc">
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<div class="t-dsc-member-div">
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<div><a href="cpp-utility-source_location-function_name.html"><span class="t-lines"><span>function_name</span></span></a></div>
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</td>
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<td>返回此对象表示的函数名,若它存在<br />
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<span class="t-mark">(公开成员函数)</span></td>
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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="t-example">
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<div class="t-example-live-link"></div>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="cpp source-cpp">
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<pre class="de1"><span class="co2">#include <iostream></span>
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<span class="co2">#include <string_view></span>
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<span class="co2">#include <source_location></span>
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<span class="kw4">void</span> log<span class="br0">(</span><a href="cpp-string-basic_string_view.html"><span class="kw1248">std::<span class="me2">string_view</span></span></a> message,
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<span class="kw4">const</span> std<span class="sy4">::</span><span class="me2">source_location</span><span class="sy3">&</span> location <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">source_location</span><span class="sy4">::</span><span class="me2">current</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span>
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<span class="br0">{</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"info:"</span>
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<span class="sy1"><<</span> location.<span class="me1">file_name</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">':'</span>
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<span class="sy1"><<</span> location.<span class="me1">line</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">' '</span>
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<span class="sy1"><<</span> message <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
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<span class="br0">}</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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log<span class="br0">(</span><span class="st0">"Hello world!"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span></pre></div>
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</div>
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<p>可能的输出:</p>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="text source-text">
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<pre class="de1">info:main.cpp:15 Hello world!</pre></div>
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</div>
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</div>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
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<div class="t-dsc-member-div">
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<div><a href="cpp-utility-stacktrace_entry.html"><span class="t-lines"><span>stacktrace_entry</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx23">(C++23)</span></span></span></div>
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</div>
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</td>
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<td>栈踪中求值的表示<br />
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<span class="t-mark">(类)</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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</body>
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