167 lines
15 KiB
HTML
167 lines
15 KiB
HTML
<!DOCTYPE html>
|
|
<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
|
|
<head><meta http-equiv="x-ua-compatible" content="ie=edge">
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
|
<title>std::basic_istringstream<CharT,Traits,Allocator>::str</title>
|
|
<link rel="stylesheet" href="ext.css" />
|
|
<link rel="stylesheet" href="site_modules.css" />
|
|
</head>
|
|
<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_io_basic_istringstream_str skin-cppreference2 action-view cpp-page-template cpp-navbar">
|
|
<div id="cpp-content-base">
|
|
<div id="content"><a id="top"></a>
|
|
<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::basic_istringstream<CharT,Traits,Allocator>::</span>str</h1>
|
|
<div id="bodyContent">
|
|
<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-io.html">io</a>‎ | <a href="cpp-io-basic_istringstream.html">basic istringstream</a></span></div>
|
|
<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
|
|
<div class="t-page-template" style="">
|
|
<p></p>
|
|
</div>
|
|
<table class="t-dcl-begin">
|
|
<tbody></tbody>
|
|
<tbody class="t-dcl-rev t-dcl-rev-num">
|
|
<tr class="t-dcl-rev-aux">
|
|
<td></td>
|
|
<td rowspan="142">(1)</td>
|
|
<td></td>
|
|
</tr>
|
|
<tr class="t-dcl t-until-cxx20">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><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,Allocator<span class="sy1">></span> str<span class="br0">(</span><span class="br0">)</span> <span class="kw4">const</span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td class="t-dcl-nopad"></td>
|
|
<td><span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl t-since-cxx20">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><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,Allocator<span class="sy1">></span> str<span class="br0">(</span><span class="br0">)</span> <span class="kw4">const</span><span class="sy3">&</span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td class="t-dcl-nopad"></td>
|
|
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
|
</tr>
|
|
</tbody>
|
|
<tbody>
|
|
<tr class="t-dcl t-since-cxx20">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span><span class="kw1">class</span> SAlloc<span class="sy1">></span><br />
|
|
<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,SAlloc<span class="sy1">></span> str<span class="br0">(</span> <span class="kw4">const</span> SAlloc<span class="sy3">&</span> a <span class="br0">)</span> <span class="kw4">const</span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td>(2)</td>
|
|
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl t-since-cxx20">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><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,Allocator<span class="sy1">></span> str<span class="br0">(</span><span class="br0">)</span> <span class="sy3">&&</span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td>(3)</td>
|
|
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw4">void</span> str<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,Allocator<span class="sy1">></span><span class="sy3">&</span> s <span class="br0">)</span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td>(4)</td>
|
|
<td class="t-dcl-nopad"></td>
|
|
</tr>
|
|
<tr class="t-dcl t-since-cxx20">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span><span class="kw1">class</span> SAlloc<span class="sy1">></span><br />
|
|
<span class="kw4">void</span> str<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, SAlloc<span class="sy1">></span><span class="sy3">&</span> s <span class="br0">)</span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td>(5)</td>
|
|
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl t-since-cxx20">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw4">void</span> str<span class="br0">(</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,Allocator<span class="sy1">></span><span class="sy3">&&</span> s <span class="br0">)</span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td>(6)</td>
|
|
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl-sep">
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<p>管理底层字符串对象的内容。</p>
|
|
<div class="t-li1"><span class="t-li">1)</span> 返回底层字符串的副本。等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">return</span> rdbuf<span class="br0">(</span><span class="br0">)</span><span class="sy2">-</span><span class="sy1">></span>str<span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span></span></span> 。</div>
|
|
<div class="t-li1"><span class="t-li">2)</span> 返回底层字符串的副本，以 <code>a</code> 为分配器。等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">return</span> rdbuf<span class="br0">(</span><span class="br0">)</span><span class="sy2">-</span><span class="sy1">></span>str<span class="br0">(</span>a<span class="br0">)</span><span class="sy4">;</span></span></span> 。</div>
|
|
<div class="t-li1"><span class="t-li">3)</span> 返回从底层字符串移动构造的字符串。等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">return</span> std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span><span class="sy2">*</span>rdbuf<span class="br0">(</span><span class="br0">)</span><span class="br0">)</span>.<span class="me1">str</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span></span></span> 。</div>
|
|
<div class="t-li1"><span class="t-li">4-5)</span> 替换底层字符串。等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp">rdbuf<span class="br0">(</span><span class="br0">)</span><span class="sy2">-</span><span class="sy1">></span>str<span class="br0">(</span>s<span class="br0">)</span><span class="sy4">;</span></span></span> 。</div>
|
|
<div class="t-li1"><span class="t-li">6)</span> 替换底层字符串。等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp">rdbuf<span class="br0">(</span><span class="br0">)</span><span class="sy2">-</span><span class="sy1">></span>str<span class="br0">(</span>std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>s<span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span></span></span> 。</div>
|
|
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
|
|
<table class="t-par-begin">
|
|
<tr class="t-par">
|
|
<td>s</td>
|
|
<td>-</td>
|
|
<td>底层字符串的新内容</td>
|
|
</tr>
|
|
<tr class="t-par">
|
|
<td>a</td>
|
|
<td>-</td>
|
|
<td>用于构造返回的字符串的分配器</td>
|
|
</tr>
|
|
</table>
|
|
<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
|
|
<div class="t-li1"><span class="t-li">1-2)</span> 底层字符串对象的副本。</div>
|
|
<div class="t-li1"><span class="t-li">3)</span> 从底层字符串对象移动构造的字符串。</div>
|
|
<div class="t-li1"><span class="t-li">4-6)</span> （无）</div>
|
|
<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">注解</span></h3>
|
|
<p><code>str</code> 所返回的底层字符串副本是将于表达式结尾析构的临时对象，故在 <span class="t-c"><span class="mw-geshi cpp source-cpp">str<span class="br0">(</span><span class="br0">)</span></span></span> 的结果上直接调用 <a href="cpp-string-basic_string-c_str.html"><tt>c_str()</tt></a> （例如 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">auto</span> <span class="sy2">*</span>ptr <span class="sy1">=</span> out.<span class="me1">str</span><span class="br0">(</span><span class="br0">)</span>.<span class="me1">c_str</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span></span></span> 中）导致悬垂指针。</p>
|
|
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
|
|
<div class="t-example">
|
|
<div class="t-example-live-link"></div>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="cpp source-cpp">
|
|
<pre class="de1"><span class="co2">#include <sstream></span>
|
|
<span class="co2">#include <iostream></span>
|
|
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
|
|
<span class="br0">{</span>
|
|
<span class="kw4">int</span> n<span class="sy4">;</span>
|
|
|
|
<a href="cpp-io-basic_istringstream.html"><span class="kw1735">std::<span class="me2">istringstream</span></span></a> in<span class="sy4">;</span> <span class="co1">// 亦可使用 in("1 2")</span>
|
|
in.<span class="me1">str</span><span class="br0">(</span><span class="st0">"1 2"</span><span class="br0">)</span><span class="sy4">;</span>
|
|
in <span class="sy1">>></span> n<span class="sy4">;</span>
|
|
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"after reading the first int from <span class="es1">\"</span>1 2<span class="es1">\"</span>, the int is "</span>
|
|
<span class="sy1"><<</span> n <span class="sy1"><<</span> <span class="st0">", str() = <span class="es1">\"</span>"</span> <span class="sy1"><<</span> in.<span class="me1">str</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">"<span class="es1">\"</span><span class="es1">\n</span>"</span><span class="sy4">;</span>
|
|
|
|
<a href="cpp-io-basic_ostringstream.html"><span class="kw1736">std::<span class="me2">ostringstream</span></span></a> out<span class="br0">(</span><span class="st0">"1 2"</span><span class="br0">)</span><span class="sy4">;</span>
|
|
out <span class="sy1"><<</span> <span class="nu0">3</span><span class="sy4">;</span>
|
|
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"after writing the int '3' to output stream <span class="es1">\"</span>1 2<span class="es1">\"</span>"</span>
|
|
<span class="sy1"><<</span> <span class="st0">", str() = <span class="es1">\"</span>"</span> <span class="sy1"><<</span> out.<span class="me1">str</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">"<span class="es1">\"</span><span class="es1">\n</span>"</span><span class="sy4">;</span>
|
|
|
|
<a href="cpp-io-basic_ostringstream.html"><span class="kw1736">std::<span class="me2">ostringstream</span></span></a> ate<span class="br0">(</span><span class="st0">"1 2"</span>, <a href="cpp-io-ios_base-openmode.html"><span class="kw1677">std::<span class="me2">ios_base</span><span class="sy4">::</span><span class="me2">ate</span></span></a><span class="br0">)</span><span class="sy4">;</span>
|
|
ate <span class="sy1"><<</span> <span class="nu0">3</span><span class="sy4">;</span>
|
|
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"after writing the int '3' to append stream <span class="es1">\"</span>1 2<span class="es1">\"</span>"</span>
|
|
<span class="sy1"><<</span> <span class="st0">", str() = <span class="es1">\"</span>"</span> <span class="sy1"><<</span> ate.<span class="me1">str</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">"<span class="es1">\"</span><span class="es1">\n</span>"</span><span class="sy4">;</span>
|
|
<span class="br0">}</span></pre></div>
|
|
</div>
|
|
<p>输出：</p>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="text source-text">
|
|
<pre class="de1">after reading the first int from "1 2", the int is 1, str() = "1 2"
|
|
after writing the int '3' to output stream "1 2", str() = "3 2"
|
|
after writing the int '3' to append stream "1 2", str() = "1 23"</pre></div>
|
|
</div>
|
|
</div>
|
|
<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-io-basic_stringbuf-str.html"><span class="t-lines"><span>str</span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>替换或获得关联字符串的副本<br />
|
|
<span class="t-mark">(<code>std::basic_stringbuf<CharT,Traits,Allocator></code> 的公开成员函数)</span></td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
<div class="visualClear"></div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
</body>
|
|
</html>
|