159 lines
9.3 KiB
HTML
159 lines
9.3 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>setbuf</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-c_io_setbuf skin-cppreference2 action-view cpp-navbar">
|
|
<div id="cpp-content-base">
|
|
<div id="content"><a id="top"></a>
|
|
<h1 id="firstHeading" class="firstHeading">setbuf</h1>
|
|
<div id="bodyContent">
|
|
<div id="contentSub"><span class="subpages">< <a href="c.html">c</a>‎ | <a href="c-io.html">io</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-dsc-header">
|
|
<td>
|
|
<div>定义于头文件 <code><stdio.h></code></div>
|
|
</td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
|
<tbody class="t-dcl-rev">
|
|
<tr class="t-dcl t-until-c99">
|
|
<td>
|
|
<div><span class="mw-geshi c source-c"><span class="kw4">void</span> setbuf<span class="br0">(</span> <a href="c-io.html"><span class="kw883">FILE</span></a> <span class="sy2">*</span>stream, <span class="kw4">char</span> <span class="sy2">*</span>buffer <span class="br0">)</span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td class="t-dcl-nopad"></td>
|
|
<td><span class="t-mark-rev t-until-c99">(C99 前)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl t-since-c99">
|
|
<td>
|
|
<div><span class="mw-geshi c source-c"><span class="kw4">void</span> setbuf<span class="br0">(</span> <a href="c-io.html"><span class="kw883">FILE</span></a> <span class="sy2">*</span><span class="kw4">restrict</span> stream, <span class="kw4">char</span> <span class="sy2">*</span><span class="kw4">restrict</span> buffer <span class="br0">)</span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td class="t-dcl-nopad"></td>
|
|
<td><span class="t-mark-rev t-since-c99">(C99 起)</span></td>
|
|
</tr>
|
|
</tbody>
|
|
<tbody>
|
|
<tr class="t-dcl-sep">
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<p>设置用于流操作的内部缓冲区。其长度至少应该为 <code>BUFSIZ</code> 个字符。</p>
|
|
<p>若 <code>buffer</code> 非空，则等价于 <span class="t-c"><span class="mw-geshi c source-c"><a href="c-io-setvbuf.html"><span class="kw823">setvbuf</span></a><span class="br0">(</span>stream, buffer, <a href="c-io.html"><span class="kw892">_IOFBF</span></a>, <a href="c-io.html"><span class="kw891">BUFSIZ</span></a><span class="br0">)</span></span></span> 。</p>
|
|
<p>若 <code>buffer</code> 为空，则等价于 <span class="t-c"><span class="mw-geshi c source-c"><a href="c-io-setvbuf.html"><span class="kw823">setvbuf</span></a><span class="br0">(</span>stream, <a href="c-types-NULL.html"><span class="kw103">NULL</span></a>, <a href="c-io.html"><span class="kw894">_IONBF</span></a>, <span class="nu0">0</span><span class="br0">)</span></span></span> ，这会关闭缓冲。</p>
|
|
<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>stream</td>
|
|
<td>-</td>
|
|
<td>要设置缓冲区的文件流</td>
|
|
</tr>
|
|
<tr class="t-par">
|
|
<td>buffer</td>
|
|
<td>-</td>
|
|
<td>指向文件流所用的缓冲区的指针。若提供空指针，则关闭缓冲。</td>
|
|
</tr>
|
|
</table>
|
|
<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
|
|
<p>无。</p>
|
|
<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">注解</span></h3>
|
|
<p>若 <span class="t-lc"><a href="c-io.html">BUFSIZ</a></span> 不是适合的缓冲区大小，则能用 <span class="t-lc"><a href="c-io-setvbuf.html">setvbuf</a></span> 更改它。</p>
|
|
<p><span class="t-lc"><a href="c-io-setvbuf.html">setvbuf</a></span> 亦应当用于检测错误，因为 <code>setbuf</code> 不指示成功或失败。</p>
|
|
<p>此函数仅可在已将 <code>stream</code> 关联到打开的文件后，但要在任何其他操作（除了对 <span class="t-lc"><strong class="selflink">setbuf</strong></span>/<code>setvbuf</code> 的失败调用）前使用。</p>
|
|
<p>一个常见错误是设置 stdin 或 stdout 的缓冲区为生存期在程序终止前结束的数组：</p>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="c source-c">
|
|
<pre class="de1"><span class="kw4">int</span> main<span class="br0">(</span><span class="kw4">void</span><span class="br0">)</span> <span class="br0">{</span>
|
|
<span class="kw4">char</span> buf<span class="br0">[</span><a href="c-io.html"><span class="kw891">BUFSIZ</span></a><span class="br0">]</span><span class="sy4">;</span>
|
|
setbuf<span class="br0">(</span><a href="c-io.html"><span class="kw885">stdin</span></a>, buf<span class="br0">)</span><span class="sy4">;</span>
|
|
<span class="br0">}</span> <span class="co1">// buf 的生存期结束，未定义行为</span></pre></div>
|
|
</div>
|
|
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
|
|
<div class="t-example">
|
|
<p>setbuf 可用于禁用要求立即输出的流的缓冲。</p>
|
|
<div class="t-example-live-link"></div>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="c source-c">
|
|
<pre class="de1"><span class="co2">#include <stdio.h></span>
|
|
<span class="co2">#include <threads.h></span>
|
|
|
|
<span class="kw4">int</span> main<span class="br0">(</span><span class="kw4">void</span><span class="br0">)</span>
|
|
<span class="br0">{</span>
|
|
setbuf<span class="br0">(</span><a href="c-io.html"><span class="kw886">stdout</span></a>, <a href="c-types-NULL.html"><span class="kw103">NULL</span></a><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// 无缓冲的 stdout</span>
|
|
<a href="c-io-putchar.html"><span class="kw834">putchar</span></a><span class="br0">(</span><span class="st0">'a'</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// 若 stdout 无缓冲，则 'a' 立即出现</span>
|
|
<a href="c-thread-thrd_sleep.html"><span class="kw999">thrd_sleep</span></a><span class="br0">(</span><span class="sy3">&</span><span class="br0">(</span><span class="kw1">struct</span> timespec<span class="br0">)</span><span class="br0">{</span>.<span class="me1">tv_sec</span><span class="sy1">=</span><span class="nu0">1</span><span class="br0">}</span>, <a href="c-types-NULL.html"><span class="kw103">NULL</span></a><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// 休眠 1 秒</span>
|
|
<a href="c-io-putchar.html"><span class="kw834">putchar</span></a><span class="br0">(</span><span class="st0">'b'</span><span class="br0">)</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">ab</pre></div>
|
|
</div>
|
|
</div>
|
|
<h3><span class="mw-headline" id=".E5.BC.95.E7.94.A8">引用</span></h3>
|
|
<div class="t-ref-std-11">
|
|
<ul>
|
|
<li>C11 标准（ISO/IEC 9899:2011）：</li>
|
|
</ul>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>7.21.5.5 The setbuf function (p: 307-308)</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<div class="t-ref-std-c99">
|
|
<ul>
|
|
<li>C99 标准（ISO/IEC 9899:1999）：</li>
|
|
</ul>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>7.19.5.5 The setbuf function (p: 273)</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<div class="t-ref-std-c89">
|
|
<ul>
|
|
<li>C89/C90 标准（ISO/IEC 9899:1990）：</li>
|
|
</ul>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>4.9.5.5 The setbuf function</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
</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="c-io-setvbuf.html"><span class="t-lines"><span>setvbuf</span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>为文件流设置缓冲区和其大小<br />
|
|
<span class="t-mark">(函数)</span></td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
<div class="visualClear"></div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
</body>
|
|
</html>
|