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181 lines
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<head>
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<meta http-equiv="content-type" content="text/html; charset=UTF-8">
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<title>查找字符串首次出现的位置</title>
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</head>
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<body class="docs"><div id="layout">
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<div id="layout-content"><div id="function.strpos" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">strpos</h1>
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<p class="verinfo">(PHP 4, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">strpos</span> — <span class="dc-title">查找字符串首次出现的位置</span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.strpos-description">
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<h3 class="title">说明</h3>
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<div class="methodsynopsis dc-description">
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<span class="methodname"><strong>strpos</strong></span>
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( <span class="methodparam"><span class="type">string</span> <code class="parameter">$haystack</code></span>
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, <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$needle</code></span>
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[, <span class="methodparam"><span class="type">int</span> <code class="parameter">$offset</code><span class="initializer"> = 0</span></span>
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] ) : <span class="type">int</span></div>
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<p class="para rdfs-comment">
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返回 <code class="parameter">needle</code> 在 <code class="parameter">haystack</code> 中首次出现的数字位置。
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</p>
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</div>
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<div class="refsect1 parameters" id="refsect1-function.strpos-parameters">
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<h3 class="title">参数</h3>
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<p class="para">
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<dl>
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<dt>
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<code class="parameter">haystack</code></dt>
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<dd>
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<p class="para">
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在该字符串中进行查找。
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</p>
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</dd>
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<dt>
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<code class="parameter">needle</code></dt>
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<dd>
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<p class="para">
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如果 <code class="parameter">needle</code> 不是一个字符串，那么它将被转换为整型并被视为字符的顺序值。
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</p>
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</dd>
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<dt>
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<code class="parameter">offset</code></dt>
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<dd>
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<p class="para">
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如果提供了此参数，搜索会从字符串该字符数的起始位置开始统计。
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如果是负数，搜索会从字符串结尾指定字符数开始。
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</p>
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</dd>
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</dl>
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</p>
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</div>
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<div class="refsect1 returnvalues" id="refsect1-function.strpos-returnvalues">
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<h3 class="title">返回值</h3>
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<p class="para">
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返回 needle 存在于 <code class="parameter">haystack</code> 字符串起始的位置(独立于 offset)。同时注意字符串位置是从0开始，而不是从1开始的。
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</p>
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<p class="para">
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如果没找到 needle，将返回 <strong><code>FALSE</code></strong>。
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</p>
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<div class="warning"><strong class="warning">Warning</strong><p class="simpara">此函数可能返回布尔值
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<strong><code>FALSE</code></strong>，但也可能返回等同于 <strong><code>FALSE</code></strong> 的非布尔值。请阅读 <a href="language.types.boolean.html" class="link">布尔类型</a>章节以获取更多信息。应使用
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<a href="language.operators.comparison.html" class="link">===
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运算符</a>来测试此函数的返回值。</p></div>
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</div>
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<div class="refsect1 changelog" id="refsect1-function.strpos-changelog">
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<h3 class="title">更新日志</h3>
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<table class="doctable informaltable">
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<thead>
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<tr>
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<th>版本</th>
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<th>说明</th>
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</tr>
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</thead>
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<tbody class="tbody">
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<tr>
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<td>7.1.0</td>
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<td>
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开始支持负数的 <code class="parameter">offset</code>。
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</td>
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</tr>
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</tbody>
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</table>
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</div>
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<div class="refsect1 examples" id="refsect1-function.strpos-examples">
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<h3 class="title">范例</h3>
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<p class="para">
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<div class="example" id="example-5974">
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<p><strong>Example #1 使用 <em>===</em></strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br />$mystring </span><span style="color: #007700">= </span><span style="color: #DD0000">'abc'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$findme </span><span style="color: #007700">= </span><span style="color: #DD0000">'a'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$pos </span><span style="color: #007700">= </span><span style="color: #0000BB">strpos</span><span style="color: #007700">(</span><span style="color: #0000BB">$mystring</span><span style="color: #007700">, </span><span style="color: #0000BB">$findme</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// 注意这里使用的是 ===。简单的 == 不能像我们期待的那样工作，<br />// 因为 'a' 是第 0 位置上的（第一个）字符。<br /></span><span style="color: #007700">if (</span><span style="color: #0000BB">$pos </span><span style="color: #007700">=== </span><span style="color: #0000BB">false</span><span style="color: #007700">) {<br /> echo </span><span style="color: #DD0000">"The string '</span><span style="color: #0000BB">$findme</span><span style="color: #DD0000">' was not found in the string '</span><span style="color: #0000BB">$mystring</span><span style="color: #DD0000">'"</span><span style="color: #007700">;<br />} else {<br /> echo </span><span style="color: #DD0000">"The string '</span><span style="color: #0000BB">$findme</span><span style="color: #DD0000">' was found in the string '</span><span style="color: #0000BB">$mystring</span><span style="color: #DD0000">'"</span><span style="color: #007700">;<br /> echo </span><span style="color: #DD0000">" and exists at position </span><span style="color: #0000BB">$pos</span><span style="color: #DD0000">"</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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</div>
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<div class="example" id="example-5975">
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<p><strong>Example #2 使用 !==</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br />$mystring </span><span style="color: #007700">= </span><span style="color: #DD0000">'abc'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$findme </span><span style="color: #007700">= </span><span style="color: #DD0000">'a'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$pos </span><span style="color: #007700">= </span><span style="color: #0000BB">strpos</span><span style="color: #007700">(</span><span style="color: #0000BB">$mystring</span><span style="color: #007700">, </span><span style="color: #0000BB">$findme</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// 使用 !== 操作符。使用 != 不能像我们期待的那样工作，<br />// 因为 'a' 的位置是 0。语句 (0 != false) 的结果是 false。<br /></span><span style="color: #007700">if (</span><span style="color: #0000BB">$pos </span><span style="color: #007700">!== </span><span style="color: #0000BB">false</span><span style="color: #007700">) {<br /> echo </span><span style="color: #DD0000">"The string '</span><span style="color: #0000BB">$findme</span><span style="color: #DD0000">' was found in the string '</span><span style="color: #0000BB">$mystring</span><span style="color: #DD0000">'"</span><span style="color: #007700">;<br /> echo </span><span style="color: #DD0000">" and exists at position </span><span style="color: #0000BB">$pos</span><span style="color: #DD0000">"</span><span style="color: #007700">;<br />} else {<br /> echo </span><span style="color: #DD0000">"The string '</span><span style="color: #0000BB">$findme</span><span style="color: #DD0000">' was not found in the string '</span><span style="color: #0000BB">$mystring</span><span style="color: #DD0000">'"</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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</div>
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<div class="example" id="example-5976">
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<p><strong>Example #3 使用位置偏移量</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// 忽视位置偏移量之前的字符进行查找<br /></span><span style="color: #0000BB">$newstring </span><span style="color: #007700">= </span><span style="color: #DD0000">'abcdef abcdef'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$pos </span><span style="color: #007700">= </span><span style="color: #0000BB">strpos</span><span style="color: #007700">(</span><span style="color: #0000BB">$newstring</span><span style="color: #007700">, </span><span style="color: #DD0000">'a'</span><span style="color: #007700">, </span><span style="color: #0000BB">1</span><span style="color: #007700">); </span><span style="color: #FF8000">// $pos = 7, 不是 0<br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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</div>
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</p>
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</div>
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<div class="refsect1 notes" id="refsect1-function.strpos-notes">
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<h3 class="title">注释</h3>
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<blockquote class="note"><p><strong class="note">Note</strong>: <span class="simpara">此函数可安全用于二进制对象。</span></p></blockquote>
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</div>
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<div class="refsect1 seealso" id="refsect1-function.strpos-seealso">
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<h3 class="title">参见</h3>
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<p class="para">
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<ul class="simplelist">
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<li class="member"><span class="function"><a href="stripos.html" class="function" rel="rdfs-seeAlso">stripos()</a> - 查找字符串首次出现的位置（不区分大小写）</span></li>
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<li class="member"><span class="function"><a href="strrpos.html" class="function" rel="rdfs-seeAlso">strrpos()</a> - 计算指定字符串在目标字符串中最后一次出现的位置</span></li>
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<li class="member"><span class="function"><a href="strripos.html" class="function" rel="rdfs-seeAlso">strripos()</a> - 计算指定字符串在目标字符串中最后一次出现的位置（不区分大小写）</span></li>
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<li class="member"><span class="function"><a href="strstr.html" class="function" rel="rdfs-seeAlso">strstr()</a> - 查找字符串的首次出现</span></li>
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<li class="member"><span class="function"><a href="strpbrk.html" class="function" rel="rdfs-seeAlso">strpbrk()</a> - 在字符串中查找一组字符的任何一个字符</span></li>
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<li class="member"><span class="function"><a href="substr.html" class="function" rel="rdfs-seeAlso">substr()</a> - 返回字符串的子串</span></li>
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<li class="member"><span class="function"><a href="preg_match.html" class="function" rel="rdfs-seeAlso">preg_match()</a> - 执行匹配正则表达式</span></li>
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</ul>
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</p>
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</div>
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</div></div></div></body></html> |