298 lines
22 KiB
HTML
298 lines
22 KiB
HTML
<!DOCTYPE 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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<head><meta http-equiv="x-ua-compatible" content="ie=edge">
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<title>strtok, strtok_s</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-c_string_byte_strtok skin-cppreference2 action-view cpp-navbar">
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<div id="cpp-content-base">
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<h1 id="firstHeading" class="firstHeading">strtok, strtok_s</h1>
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<div id="bodyContent">
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<div id="contentSub"><span class="subpages">< <a href="c.html">c</a>‎ | <a href="c-string.html">string</a>‎ | <a href="c-string-byte.html">byte</a></span></div>
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<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
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<table class="t-dcl-begin">
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<td>
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<div>定义于头文件 <code><string.h></code></div>
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</td>
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<td></td>
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<td></td>
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<tbody class="t-dcl-rev t-dcl-rev-num">
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<td></td>
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<td rowspan="142">(1)</td>
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<td></td>
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<tr class="t-dcl t-until-c99">
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<div><span class="mw-geshi c source-c"><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>
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</td>
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<td class="t-dcl-nopad"></td>
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<td><span class="t-mark-rev t-until-c99">(C99 前)</span></td>
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</tr>
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<tr class="t-dcl t-since-c99">
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<td>
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<div><span class="mw-geshi c source-c"><span class="kw4">char</span> <span class="sy2">*</span>strtok<span class="br0">(</span> <span class="kw4">char</span> <span class="sy2">*</span><span class="kw4">restrict</span> str, <span class="kw4">const</span> <span class="kw4">char</span> <span class="sy2">*</span><span class="kw4">restrict</span> delim <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td class="t-dcl-nopad"></td>
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<td><span class="t-mark-rev t-since-c99">(C99 起)</span></td>
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</tr>
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</tbody>
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<tbody></tbody>
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<tbody>
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<tr class="t-dcl t-since-c11">
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<td>
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<div><span class="mw-geshi c source-c"><span class="kw4">char</span> <span class="sy2">*</span>strtok_s<span class="br0">(</span><span class="kw4">char</span> <span class="sy2">*</span><span class="kw4">restrict</span> str, rsize_t <span class="sy2">*</span><span class="kw4">restrict</span> strmax,<br />
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<span class="kw4">const</span> <span class="kw4">char</span> <span class="sy2">*</span><span class="kw4">restrict</span> delim, <span class="kw4">char</span> <span class="sy2">**</span><span class="kw4">restrict</span> ptr<span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(2)</td>
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<td><span class="t-mark-rev t-since-c11">(C11 起)</span></td>
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</tr>
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<tr class="t-dcl-sep">
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<td></td>
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<td></td>
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<td></td>
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</tbody>
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</table>
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<div class="t-li1"><span class="t-li">1)</span> 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。</div>
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<div class="t-li1"><span class="t-li"></span> 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。</div>
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<dl>
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<dd>
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<ul>
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<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>
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</ul>
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<dl>
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<dd>
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<ul>
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<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>
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<li>若找到这种字符，则它是<i>记号的起始</i>。然后函数从该点搜索首个<i>含于</i> <code>delim</code> 的字符。</li>
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</ul>
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<dl>
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<dd>
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<ul>
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<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>
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<li>若找到这种字符，则用空字符 <span class="t-c"><span class="mw-geshi c source-c"><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>
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</ul>
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</dd>
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</dl>
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<ul>
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<li>然后函数返回指向记号起始的指针</li>
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</ul>
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</dd>
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</dl>
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<ul>
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<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 c source-c">str</span></span> 传递。</li>
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</ul>
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</dd>
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</dl>
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<div class="t-li1"><span class="t-li"></span> 若<code>str</code> 或 <code>delim</code> 不是指向空终止字节字符串的指针，则行为未定义。</div>
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<div class="t-li1"><span class="t-li">2)</span> 同 <span class="t-v">(1)</span> ，除了在每步时，写入 <code>str</code> 中留待查看的字符数到 <span class="t-c"><span class="mw-geshi c source-c"><span class="sy2">*</span>strmax</span></span> ，并写入记号化器的初始状态到 <span class="t-c"><span class="mw-geshi c source-c"><span class="sy2">*</span>ptr</span></span> 。重复的调用（以空 <code>str</code> ）必须传递先前的调用用以存储值的 <code>strmax</code> 和 <code>ptr</code> 。另外，在运行时检测下列错误并调用当前安装的<a href="c-error-set_constraint_handler_s.html">制约处理</a>函数，而不存储任何内容到 <code>ptr</code> 所指向的对象：
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<dl>
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<dd>
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<ul>
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<li><code>strmax</code> 、 <code>delim</code> 或 <code>ptr</code> 为空指针</li>
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<li>非首次调用（以 <code>str</code> ）时， <code>*ptr</code> 为空指针</li>
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<li>首次调用时， <span class="t-c"><span class="mw-geshi c source-c"><span class="sy2">*</span>strmax</span></span> 为零或大于 <span class="t-lc">RSIZE_MAX</span></li>
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<li>对记号尾的搜索抵达源字符串的结尾（由 <span class="t-c"><span class="mw-geshi c source-c"><span class="sy2">*</span>strmax</span></span> 的初值测量）而未遇到空终止符</li>
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</ul>
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</dd>
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</dl>
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</div>
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<div class="t-li1"><span class="t-li"></span> 若 <code>str</code> 指向的字符数组缺少空终止符，而 <code>strmax</code> 指向的值大于该字符数组长度，则行为未定义。
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<dl>
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<dd>同所有边界检查函数， <code>strtok_s</code> 仅若实现定义 <span class="t-c"><span class="mw-geshi c source-c">__STDC_LIB_EXT1__</span></span> 且用户在包含 <code>string.h</code> 前定义 <span class="t-c"><span class="mw-geshi c source-c">__STDC_WANT_LIB_EXT1__</span></span> 为整数常量 1 才保证可用。</dd>
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</dl>
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</div>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
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<table class="t-par-begin">
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<tr class="t-par">
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<td>str</td>
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<td>-</td>
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<td>指向要记号化的空终止字节字符串的指针</td>
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</tr>
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<tr class="t-par">
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<td>delim</td>
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<td>-</td>
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<td>指向标识分隔符的空终止字节字符串的指针</td>
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</tr>
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<tr class="t-par">
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<td>strmax</td>
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<td>-</td>
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<td>指向最初保有 <code>str</code> 长度的对象指针： <code>strtok_s</code> 存储留待检验的字符数</td>
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</tr>
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<tr class="t-par">
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<td>ptr</td>
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<td>-</td>
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<td>指向 <span class="t-c"><span class="mw-geshi c source-c"><span class="kw4">char</span><span class="sy2">*</span></span></span> 类型对象的指针， <code>strtok_s</code> 以之存储其内部状态</td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
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<p>返回指向下个记号起始的指针，或若无更多记号则返回空指针。</p>
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<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">注解</span></h3>
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<p>此函数是破坏性的：它写入 <span class="t-c"><span class="mw-geshi c source-c"><span class="st0">'<span class="es5">\0</span>'</span></span></span> 字符到字符串 <code>str</code> 的元素。特别是，不能以字符串字面量为 <code>strtok</code> 的首参数。</p>
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<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>
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<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>
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<p><code>strtok_s</code> 函数异于 POSIX <a rel="nofollow" class="external text" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/strtok.html"><code>strtok_r</code></a> 函数，前者通过在被记号化的字符串外部存储，和检查运行时制约来防护。</p>
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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="c source-c">
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<pre class="de1"><span class="co2">#define __STDC_WANT_LIB_EXT1__ 1</span>
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<span class="co2">#include <string.h></span>
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<span class="co2">#include <stdio.h></span>
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<span class="kw4">int</span> main<span class="br0">(</span><span class="kw4">void</span><span class="br0">)</span>
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<span class="br0">{</span>
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<span class="kw4">char</span> input<span class="br0">[</span><span class="br0">]</span> <span class="sy1">=</span> <span class="st0">"A bird came down the walk"</span><span class="sy4">;</span>
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<a href="c-io-fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">"Parsing the input string '%s'<span class="es1">\n</span>"</span>, input<span class="br0">)</span><span class="sy4">;</span>
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<span class="kw4">char</span> <span class="sy2">*</span>token <span class="sy1">=</span> strtok<span class="br0">(</span>input, <span class="st0">" "</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">while</span><span class="br0">(</span>token<span class="br0">)</span> <span class="br0">{</span>
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<a href="c-io-puts.html"><span class="kw835">puts</span></a><span class="br0">(</span>token<span class="br0">)</span><span class="sy4">;</span>
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token <span class="sy1">=</span> strtok<span class="br0">(</span><a href="c-types-NULL.html"><span class="kw103">NULL</span></a>, <span class="st0">" "</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<a href="c-io-fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">"Contents of the input string now: '"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">for</span><span class="br0">(</span><a href="c-types-size_t.html"><span class="kw100">size_t</span></a> n <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span> n <span class="sy1"><</span> <span class="kw4">sizeof</span> input<span class="sy4">;</span> <span class="sy2">++</span>n<span class="br0">)</span>
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input<span class="br0">[</span>n<span class="br0">]</span> <span class="sy4">?</span> <a href="c-io-putchar.html"><span class="kw834">putchar</span></a><span class="br0">(</span>input<span class="br0">[</span>n<span class="br0">]</span><span class="br0">)</span> <span class="sy4">:</span> <a href="c-io-fputs.html"><span class="kw831">fputs</span></a><span class="br0">(</span><span class="st0">"<span class="es1">\\</span>0"</span>, <a href="c-io.html"><span class="kw886">stdout</span></a><span class="br0">)</span><span class="sy4">;</span>
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<a href="c-io-puts.html"><span class="kw835">puts</span></a><span class="br0">(</span><span class="st0">"'"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="co2">#ifdef __STDC_LIB_EXT1__</span>
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<span class="kw4">char</span> str<span class="br0">[</span><span class="br0">]</span> <span class="sy1">=</span> <span class="st0">"A bird came down the walk"</span><span class="sy4">;</span>
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rsize_t strmax <span class="sy1">=</span> <span class="kw4">sizeof</span> str<span class="sy4">;</span>
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<span class="kw4">const</span> <span class="kw4">char</span> <span class="sy2">*</span>delim <span class="sy1">=</span> <span class="st0">" "</span><span class="sy4">;</span>
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<span class="kw4">char</span> <span class="sy2">*</span>next_token<span class="sy4">;</span>
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<a href="c-io-fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">"Parsing the input string '%s'<span class="es1">\n</span>"</span>, str<span class="br0">)</span><span class="sy4">;</span>
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token <span class="sy1">=</span> strtok_s<span class="br0">(</span>str, <span class="sy3">&</span>strmax, delim, <span class="sy3">&</span>next_token<span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">while</span><span class="br0">(</span>token<span class="br0">)</span> <span class="br0">{</span>
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<a href="c-io-puts.html"><span class="kw835">puts</span></a><span class="br0">(</span>token<span class="br0">)</span><span class="sy4">;</span>
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token <span class="sy1">=</span> strtok_s<span class="br0">(</span><a href="c-types-NULL.html"><span class="kw103">NULL</span></a>, <span class="sy3">&</span>strmax, delim, <span class="sy3">&</span>next_token<span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<a href="c-io-fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">"Contents of the input string now: '"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">for</span><span class="br0">(</span><a href="c-types-size_t.html"><span class="kw100">size_t</span></a> n <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span> n <span class="sy1"><</span> <span class="kw4">sizeof</span> str<span class="sy4">;</span> <span class="sy2">++</span>n<span class="br0">)</span>
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str<span class="br0">[</span>n<span class="br0">]</span> <span class="sy4">?</span> <a href="c-io-putchar.html"><span class="kw834">putchar</span></a><span class="br0">(</span>str<span class="br0">[</span>n<span class="br0">]</span><span class="br0">)</span> <span class="sy4">:</span> <a href="c-io-fputs.html"><span class="kw831">fputs</span></a><span class="br0">(</span><span class="st0">"<span class="es1">\\</span>0"</span>, <a href="c-io.html"><span class="kw886">stdout</span></a><span class="br0">)</span><span class="sy4">;</span>
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<a href="c-io-puts.html"><span class="kw835">puts</span></a><span class="br0">(</span><span class="st0">"'"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="co2">#endif</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">Parsing the input string 'A bird came down the walk'
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A
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bird
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came
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down
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the
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walk
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Contents of the input string now: 'A\0bird\0came\0down\0the\0walk\0'
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Parsing the input string 'A bird came down the walk'
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A
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bird
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came
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down
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the
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walk
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Contents of the input string now: 'A\0bird\0came\0down\0the\0walk\0'</pre></div>
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</div>
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</div>
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<h3><span class="mw-headline" id=".E5.BC.95.E7.94.A8">引用</span></h3>
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<div class="t-ref-std-11">
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<ul>
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<li>C11 标准（ISO/IEC 9899:2011）：</li>
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</ul>
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<dl>
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<dd>
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<ul>
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<li>7.24.5.8 The strtok function (p: 369-370)</li>
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</ul>
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</dd>
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</dl>
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<dl>
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<dd>
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<ul>
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<li>K.3.7.3.1 The strtok_s function (p: 620-621)</li>
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</ul>
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</dd>
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</dl>
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<div class="t-ref-std-c99">
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<ul>
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<li>C99 标准（ISO/IEC 9899:1999）：</li>
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</ul>
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<dl>
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<dd>
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<ul>
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<li>7.21.5.8 The strtok function (p: 332-333)</li>
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</ul>
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</dd>
|
|
</dl>
|
|
<div class="t-ref-std-c89">
|
|
<ul>
|
|
<li>C89/C90 标准（ISO/IEC 9899:1990）：</li>
|
|
</ul>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>4.11.5.8 The strtok 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-string-byte-strpbrk.html"><span class="t-lines"><span>strpbrk</span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>查找一个字符串中的任意一个字符在另一个字符串中的首个位置<br />
|
|
<span class="t-mark">(函数)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="c-string-byte-strcspn.html"><span class="t-lines"><span>strcspn</span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>返回另一个字符串所不具有的字符分割的最大起始段长度<br />
|
|
<span class="t-mark">(函数)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="c-string-byte-strspn.html"><span class="t-lines"><span>strspn</span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>返回由另一个字符串中的字符分割的最大起始段长度<br />
|
|
<span class="t-mark">(函数)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="c-string-wide-wcstok.html"><span class="t-lines"><span>wcstok</span><span>wcstok_s</span></span></a></div>
|
|
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c95">(C95)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>查找宽字符串中的下一个记号<br />
|
|
<span class="t-mark">(函数)</span></td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
<div class="visualClear"></div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
</body>
|
|
</html>
|