170 lines
11 KiB
HTML
170 lines
11 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_ostream<CharT,Traits>::seekp</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_ostream_seekp skin-cppreference2 action-view 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_ostream<CharT,Traits>::</span>seekp</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_ostream.html">basic ostream</a></span></div>
|
|
<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
|
|
<table class="t-dcl-begin">
|
|
<tbody>
|
|
<tr class="t-dcl">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp">basic_ostream<span class="sy3">&</span> seekp<span class="br0">(</span> pos_type pos <span class="br0">)</span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td>(1)</td>
|
|
<td class="t-dcl-nopad"></td>
|
|
</tr>
|
|
<tr class="t-dcl">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp">basic_ostream<span class="sy3">&</span> seekp<span class="br0">(</span> off_type off, <a href="cpp-io-ios_base-seekdir.html"><span class="kw1702">std::<span class="me2">ios_base</span><span class="sy4">::</span><span class="me2">seekdir</span></span></a> dir <span class="br0">)</span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td>(2)</td>
|
|
<td class="t-dcl-nopad"></td>
|
|
</tr>
|
|
<tr class="t-dcl-sep">
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<p>设置当前关联 <code>streambuf</code> 对象的输出位置指示器。</p>
|
|
<table class="t-rev-begin">
|
|
<tr class="t-rev t-since-cxx11">
|
|
<td>
|
|
<p>表现为<a href="cpp-named_req-UnformattedOutputFunction.html"><span style="font-style:italic">无格式输出函数</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(UnformattedOutputFunction)</span></a> (除了不实际进行输出)。在构造并检查 sentry 对象后,</p>
|
|
</td>
|
|
<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
|
|
</tr>
|
|
</table>
|
|
<div class="t-li1"><span class="t-li">1)</span> 通过调用 <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>pubseekpos<span class="br0">(</span>pos, <a href="cpp-io-ios_base-openmode.html"><span class="kw1675">std::<span class="me2">ios_base</span><span class="sy4">::</span><span class="me2">out</span></span></a><span class="br0">)</span></span></span> ,设置输出位置指示器为绝对(相对于文件起始)值 <code>pos</code> 。若调用返回 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="br0">(</span>pos_type<span class="br0">)</span><span class="sy2">-</span><span class="nu0">1</span></span></span> ,则执行 <span class="t-c"><span class="mw-geshi cpp source-cpp">setstate<span class="br0">(</span>failbit<span class="br0">)</span></span></span> 。</div>
|
|
<div class="t-li1"><span class="t-li">2)</span> 通过调用 <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>pubseekoff<span class="br0">(</span>off, dir, <a href="cpp-io-ios_base-openmode.html"><span class="kw1675">std::<span class="me2">ios_base</span><span class="sy4">::</span><span class="me2">out</span></span></a><span class="br0">)</span></span></span> 设置输出位置指示器为相对于 <code>dir</code> 的偏移 <code>off</code> 。若调用返回 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="br0">(</span>pos_type<span class="br0">)</span><span class="sy2">-</span><span class="nu0">1</span></span></span> ,则执行 <span class="t-c"><span class="mw-geshi cpp source-cpp">setstate<span class="br0">(</span>failbit<span class="br0">)</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>pos</td>
|
|
<td>-</td>
|
|
<td>要设置输出位置指示器到的绝对位置。</td>
|
|
</tr>
|
|
<tr class="t-par">
|
|
<td>off</td>
|
|
<td>-</td>
|
|
<td>要设置输出位置指示器到的相对位置(正或负)。</td>
|
|
</tr>
|
|
<tr class="t-par">
|
|
<td>dir</td>
|
|
<td>-</td>
|
|
<td>定义应用相对偏移到的基位置。它能为下列常量之一:
|
|
<table class="t-dsc-begin">
|
|
<tr class="t-dsc-hitem">
|
|
<td>常量</td>
|
|
<td>解释</td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td><a href="cpp-io-ios_base-seekdir.html"><tt>beg</tt></a></td>
|
|
<td>流的开始</td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td><a href="cpp-io-ios_base-seekdir.html"><tt>end</tt></a></td>
|
|
<td>流的结尾</td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td><a href="cpp-io-ios_base-seekdir.html"><tt>cur</tt></a></td>
|
|
<td>流位置指示器的当前位置</td>
|
|
</tr>
|
|
</table>
|
|
</td>
|
|
</tr>
|
|
</table>
|
|
<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
|
|
<p><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span></p>
|
|
<h3><span class="mw-headline" id=".E5.BC.82.E5.B8.B8">异常</span></h3>
|
|
<div class="t-li1"><span class="t-li">1-2)</span> 若 <span class="t-c"><span class="mw-geshi cpp source-cpp">exceptions<span class="br0">(</span><span class="br0">)</span> <span class="sy3">&</span> failbit <span class="sy3">!</span><span class="sy1">=</span> <span class="nu0">0</span></span></span> ,则失败情况下可以抛出 <span class="t-lc"><a href="cpp-io-ios_base-failure.html">std::ios_base::failure</a></span> 。</div>
|
|
<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>
|
|
<a href="cpp-io-basic_ostringstream.html"><span class="kw1736">std::<span class="me2">ostringstream</span></span></a> os<span class="br0">(</span><span class="st0">"hello, world"</span><span class="br0">)</span><span class="sy4">;</span>
|
|
os.<span class="me1">seekp</span><span class="br0">(</span><span class="nu0">7</span><span class="br0">)</span><span class="sy4">;</span>
|
|
os <span class="sy1"><<</span> <span class="st0">'W'</span><span class="sy4">;</span>
|
|
os.<span class="me1">seekp</span><span class="br0">(</span><span class="nu0">0</span>, <a href="cpp-io-ios_base-seekdir.html"><span class="kw1705">std::<span class="me2">ios_base</span><span class="sy4">::</span><span class="me2">end</span></span></a><span class="br0">)</span><span class="sy4">;</span>
|
|
os <span class="sy1"><<</span> <span class="st0">'!'</span><span class="sy4">;</span>
|
|
os.<span class="me1">seekp</span><span class="br0">(</span><span class="nu0">0</span><span class="br0">)</span><span class="sy4">;</span>
|
|
os <span class="sy1"><<</span> <span class="st0">'H'</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> os.<span class="me1">str</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<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">Hello, World!</pre></div>
|
|
</div>
|
|
</div>
|
|
<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/issue2341">LWG 2341</a></td>
|
|
<td>C++98</td>
|
|
<td>二个重载在失败时表现有别</td>
|
|
<td>使之一致</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-io-basic_ostream-tellp.html"><span class="t-lines"><span>tellp</span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>返回输出位置指示器<br />
|
|
<span class="t-mark">(公开成员函数)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-io-basic_istream-tellg.html"><span class="t-lines"><span>tellg</span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>返回输入位置指示器<br />
|
|
<span class="t-mark">(<code>std::basic_istream<CharT,Traits></code> 的公开成员函数)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-io-basic_istream-seekg.html"><span class="t-lines"><span>seekg</span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>设置输入位置指示器<br />
|
|
<span class="t-mark">(<code>std::basic_istream<CharT,Traits></code> 的公开成员函数)</span></td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
<div class="visualClear"></div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
</body>
|
|
</html>
|