151 lines
10 KiB
HTML
151 lines
10 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::strtok</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_string_byte_strtok 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::</span>strtok</h1>
|
|
<div id="bodyContent">
|
|
<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-string.html">string</a>‎ | <a href="cpp-string-byte.html">byte</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><a href="cpp-header-cstring.html"><cstring></a></code></div>
|
|
</td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
<tr class="t-dcl">
|
|
<td class="t-dcl-nopad">
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw4">char</span><span class="sy2">*</span> strtok<span class="br0">(</span> <span class="kw4">char</span><span class="sy2">*</span> str, <span class="kw4">const</span> <span class="kw4">char</span><span class="sy2">*</span> delim <span class="br0">)</span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td class="t-dcl-nopad"></td>
|
|
<td class="t-dcl-nopad"></td>
|
|
</tr>
|
|
<tr class="t-dcl-sep">
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<p>寻找 <code>str</code> 所指向的空终止字节字符串中的下个记号。由 <code>delim</code> 所指向的空终止字节字符串鉴别分隔字符。</p>
|
|
<p>此函数被设计为调用多次，以从同一字符串获得相继的记号。</p>
|
|
<ul>
|
|
<li>若 <code>str</code> 不是空指针，则调用被当做 <code>strtok</code> 对此特定字符串的首次调用。函数搜索首个<i>不</i>含于 <code>delim</code> 的字符。</li>
|
|
</ul>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>若找不到这种字符，则 <code>str</code> 中完全没有记号，而函数返回空指针。</li>
|
|
<li>若找到这种字符，则它是<i>记号的起始</i>。然后函数从 <code>delim</code> <i>所含</i>的首个字符的该点搜索。</li>
|
|
</ul>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>若找不到这种字符，则 <code>str</code> 只有一个记号，而将来对 <code>strtok</code> 的调用将返回空指针</li>
|
|
<li>若找到这种字符，则用空字符 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="st0">'<span class="es5">\0</span>'</span></span></span> <i>替换</i>它，并将指向下个字符的指针存储于静态位置，以为后继调用所用。</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<ul>
|
|
<li>然后函数返回指向记号起始的指针</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<ul>
|
|
<li>若 <code>str</code> 为空指针，则将调用当做对 <code>strtok</code> 的后继调用，函数从先前调用中它剩下的位置开始。行为如同将先前存储的指针作为 <span class="t-c"><span class="mw-geshi cpp source-cpp">str</span></span> 传递。</li>
|
|
</ul>
|
|
<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>str</td>
|
|
<td>-</td>
|
|
<td>指向要记号化的空终止字节字符串的指针</td>
|
|
</tr>
|
|
<tr class="t-par">
|
|
<td>delim</td>
|
|
<td>-</td>
|
|
<td>指向标识分隔符的空终止字节字符串的指针</td>
|
|
</tr>
|
|
</table>
|
|
<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
|
|
<p>指向下个记号起始的指针，或若无更多记号则为空指针。</p>
|
|
<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">注解</span></h3>
|
|
<p>此函数是破坏性的：它写入 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="st0">'<span class="es5">\0</span>'</span></span></span> 字符于字符串 <code>str</code> 的元素。特别是，<a href="cpp-language-string_literal.html">字符串字面量</a>不能用作 <code>strtok</code> 的首参数。</p>
|
|
<p>每次对 <code>strtok</code> 的调用都会修改静态对象：它不是线程安全的。</p>
|
|
<p>不同于大多数其他记号化器， <code>strtok</code> 中的分隔符能对于后继记号不同，而且甚至能依赖于先前记号的内容。</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 <cstring></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">char</span> input<span class="br0">[</span><span class="nu0">100</span><span class="br0">]</span> <span class="sy1">=</span> <span class="st0">"A bird came down the walk"</span><span class="sy4">;</span>
|
|
<span class="kw4">char</span> <span class="sy2">*</span>token <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">strtok</span><span class="br0">(</span>input, <span class="st0">" "</span><span class="br0">)</span><span class="sy4">;</span>
|
|
<span class="kw1">while</span> <span class="br0">(</span>token <span class="sy3">!</span><span class="sy1">=</span> <a href="cpp-types-NULL.html"><span class="kw103">NULL</span></a><span class="br0">)</span> <span class="br0">{</span>
|
|
<a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> token <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
|
|
token <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">strtok</span><span class="br0">(</span><a href="cpp-types-NULL.html"><span class="kw103">NULL</span></a>, <span class="st0">" "</span><span class="br0">)</span><span class="sy4">;</span>
|
|
<span class="br0">}</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">A
|
|
bird
|
|
came
|
|
down
|
|
the
|
|
walk</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-string-byte-strpbrk.html"><span class="t-lines"><span>strpbrk</span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>寻找任何来自分隔符集合的字符的首个位置<br />
|
|
<span class="t-mark">(函数)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-string-byte-strcspn.html"><span class="t-lines"><span>strcspn</span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>返回仅由另一字节字符串中找不到的字符组成的最大起始段的长度<br />
|
|
<span class="t-mark">(函数)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-string-byte-strspn.html"><span class="t-lines"><span>strspn</span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>返回仅由另一字节字符串中找到的字符组成的最大起始段的长度<br />
|
|
<span class="t-mark">(函数)</span></td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
<div class="visualClear"></div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
</body>
|
|
</html>
|