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https://github.com/fofolee/uTools-Manuals.git
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147 lines
5.3 KiB
HTML
147 lines
5.3 KiB
HTML
<!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>获取字符的一部分</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.mb-strcut" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">mb_strcut</h1>
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<p class="verinfo">(PHP 4 >= 4.0.6, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">mb_strcut</span> — <span class="dc-title">获取字符的一部分</span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.mb-strcut-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>mb_strcut</strong></span>
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( <span class="methodparam"><span class="type">string</span> <code class="parameter">$str</code></span>
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, <span class="methodparam"><span class="type">int</span> <code class="parameter">$start</code></span>
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[, <span class="methodparam"><span class="type">int</span> <code class="parameter">$length</code><span class="initializer"> = NULL</span></span>
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[, <span class="methodparam"><span class="type">string</span> <code class="parameter">$encoding</code><span class="initializer"> = mb_internal_encoding()</span></span>
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]] ) : <span class="type">string</span></div>
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<p class="para rdfs-comment">
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<span class="function"><strong>mb_strcut()</strong></span> 和 <span class="function"><a href="mb_substr.html" class="function">mb_substr()</a></span> 类似，都是从字符串中提取子字符串，但是按字节数来执行，而不是字符个数。
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如果截断位置位于多字节字符两个字节的中间，将于该字符的第一个字节开始执行。
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这也是和 <span class="function"><a href="substr.html" class="function">substr()</a></span> 函数的不同之处，后者简单地将字符串在字节之间截断，这将导致一个畸形的字节序列。
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</p>
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</div>
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<div class="refsect1 parameters" id="refsect1-function.mb-strcut-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">str</code></dt>
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<dd>
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<p class="para">
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要截断的 <span class="type"><a href="language.types.string.html" class="type string">string</a></span>。
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</p>
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</dd>
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<dt>
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<code class="parameter">start</code></dt>
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<dd>
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<p class="para">
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如果 <code class="parameter">start</code> 不是负数，返回的字符串会从 <code class="parameter">str</code> 的第 <code class="parameter">start</code> <em class="emphasis">字节</em>位置开始，从 0 开始计数。举个例子，字符串 '<em>abcdef</em>'，字节位置 <em>0</em> 的字符是 '<em>a</em>'，字节位置 <em>2</em> 的字符是
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'<em>c</em>'，以此类推。
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</p>
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<p class="para">
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如果 <code class="parameter">start</code> 是负数，返回的字符串是从 <code class="parameter">str</code> 末尾处第 <code class="parameter">start</code> 个字节开始的。
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</p>
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</dd>
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<dt>
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<code class="parameter">length</code></dt>
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<dd>
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<p class="para">
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<em class="emphasis">字节</em>长度。If omitted or <em>NULL</em>
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is passed, extract all bytes to the end of the string.
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</p>
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</dd>
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<dt>
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<code class="parameter">encoding</code></dt>
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<dd>
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<p class="para"><code class="parameter">encoding</code>
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参数为字符编码。如果省略，则使用内部字符编码。</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.mb-strcut-returnvalues">
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<h3 class="title">返回值</h3>
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<p class="para">
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<span class="function"><strong>mb_strcut()</strong></span> 根据 <code class="parameter">start</code> 和 <code class="parameter">length</code> 参数返回 <code class="parameter">str</code> 的一部分。
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</p>
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</div>
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<div class="refsect1 changelog" id="refsect1-function.mb-strcut-changelog">
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<h3 class="title">更新日志</h3>
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<p class="para">
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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>5.4.8</td>
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<td>
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Passing <em>NULL</em> as <code class="parameter">length</code>
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extracts all bytes to the end of the string. Prior to this version
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<em>NULL</em> was treated the same as <em>0</em>.
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</td>
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</tr>
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</tbody>
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</table>
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</p>
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</div>
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<div class="refsect1 seealso" id="refsect1-function.mb-strcut-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="mb_substr.html" class="function" rel="rdfs-seeAlso">mb_substr()</a> - 获取部分字符串</span></li>
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<li class="member"><span class="function"><a href="mb_internal_encoding.html" class="function" rel="rdfs-seeAlso">mb_internal_encoding()</a> - 设置/获取内部字符编码</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> |