159 lines
7.7 KiB
HTML
159 lines
7.7 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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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<title>strstr</title>
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<link rel="stylesheet" href="ext.css" />
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<link rel="stylesheet" href="site_modules.css" />
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</head>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-c_string_byte_strstr skin-cppreference2 action-view cpp-navbar">
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<div id="cpp-content-base">
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<div id="content"><a id="top"></a>
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<h1 id="firstHeading" class="firstHeading">strstr</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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<tbody>
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<tr class="t-dsc-header">
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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></td>
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<td></td>
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<tr class="t-dcl">
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<div><span class="mw-geshi c source-c"><span class="kw4">char</span> <span class="sy2">*</span>strstr<span class="br0">(</span> <span class="kw4">const</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> substr <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td class="t-dcl-nopad"></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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</tr>
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</tbody>
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</table>
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<p>查找 <code>substr</code> 所指的空终止字节字符串在 <code>str</code> 所指的空终止字节字符串中的首次出现。不比较空终止字符。</p>
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<p>若 <code>str</code> 或 <code>substr</code> 不是指向空终止字节字符串的指针,则行为未定义。</p>
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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>指向要检验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>substr</td>
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<td>-</td>
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<td>指向要查找的空终止字节字符串的指针</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>指向于 <code>str</code> 中找到的子串首字符的指针,或若找不到该子串则为空指针。若 <code>substr</code> 指向空字符串,则返回 <code>str</code> 。</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">#include <string.h></span>
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<span class="co2">#include <stdio.h></span>
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<span class="kw4">void</span> find_str<span class="br0">(</span><span class="kw4">char</span> <span class="kw4">const</span><span class="sy2">*</span> str, <span class="kw4">char</span> <span class="kw4">const</span><span class="sy2">*</span> substr<span class="br0">)</span>
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<span class="br0">{</span>
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<span class="kw4">char</span><span class="sy2">*</span> pos <span class="sy1">=</span> strstr<span class="br0">(</span>str, substr<span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">if</span><span class="br0">(</span>pos<span class="br0">)</span> <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">"found the string '%s' in '%s' at position: %ld<span class="es1">\n</span>"</span>, substr, str, pos <span class="sy2">-</span> str<span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span> <span class="kw1">else</span> <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">"the string '%s' was not found in '%s'<span class="es1">\n</span>"</span>, substr, str<span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="br0">}</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><span class="sy2">*</span> str <span class="sy1">=</span> <span class="st0">"one two three"</span><span class="sy4">;</span>
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find_str<span class="br0">(</span>str, <span class="st0">"two"</span><span class="br0">)</span><span class="sy4">;</span>
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find_str<span class="br0">(</span>str, <span class="st0">""</span><span class="br0">)</span><span class="sy4">;</span>
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find_str<span class="br0">(</span>str, <span class="st0">"nine"</span><span class="br0">)</span><span class="sy4">;</span>
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find_str<span class="br0">(</span>str, <span class="st0">"n"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">return</span> <span class="nu0">0</span><span class="sy4">;</span>
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<span class="br0">}</span></pre></div>
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</div>
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<p>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">found the string 'two' in 'one two three' at position: 4
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found the string '' in 'one two three' at position: 0
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the string 'nine' was not found in 'one two three'
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found the string 'n' in 'one two three' at position: 1</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>7.24.5.7 The strstr function (p: 369)</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>7.21.5.7 The strstr function (p: 332)</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-c89">
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<ul>
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<li>C89/C90 标准(ISO/IEC 9899:1990):</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>4.11.5.7 The strstr function</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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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
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<table class="t-dsc-begin">
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="c-string-byte-strchr.html"><span class="t-lines"><span>strchr</span></span></a></div>
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</div>
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</td>
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<td>查找字符的首次出现<br />
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<span class="t-mark">(函数)</span></td>
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</tr>
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="c-string-byte-strrchr.html"><span class="t-lines"><span>strrchr</span></span></a></div>
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</div>
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</td>
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<td>查找字符的最后一次出现<br />
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<span class="t-mark">(函数)</span></td>
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</tr>
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</table>
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</div>
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</div>
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</div>
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<div class="visualClear"></div>
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</div>
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</div>
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</div>
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</body>
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</html>
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