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182 lines
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HTML
182 lines
8.8 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>从数组中取出一段</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.array-slice" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">array_slice</h1>
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<p class="verinfo">(PHP 4, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">array_slice</span> — <span class="dc-title">从数组中取出一段</span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.array-slice-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>array_slice</strong></span>
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( <span class="methodparam"><span class="type">array</span> <code class="parameter">$array</code></span>
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, <span class="methodparam"><span class="type">int</span> <code class="parameter">$offset</code></span>
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[, <span class="methodparam"><span class="type">int</span> <code class="parameter">$length</code><span class="initializer"> = <strong><code>NULL</code></strong></span></span>
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[, <span class="methodparam"><span class="type">bool</span> <code class="parameter">$preserve_keys</code><span class="initializer"> = false</span></span>
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]] ) : <span class="type">array</span></div>
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<p class="para rdfs-comment">
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<span class="function"><strong>array_slice()</strong></span> 返回根据 <code class="parameter">offset</code> 和
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<code class="parameter">length</code> 参数所指定的 <code class="parameter">array</code>
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数组中的一段序列。
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</p>
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</div>
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<div class="refsect1 parameters" id="refsect1-function.array-slice-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">array</code></dt>
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<dd>
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<p class="para">
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输入的数组。
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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 <code class="parameter">offset</code> 非负，则序列将从 <code class="parameter">array</code>
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中的此偏移量开始。如果 <code class="parameter">offset</code> 为负，则序列将从
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<code class="parameter">array</code> 中距离末端这么远的地方开始。
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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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如果给出了 <code class="parameter">length</code> 并且为正，则序列中将具有这么多的单元。如果给出了
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<code class="parameter">length</code> 并且为负，则序列将终止在距离数组末端这么远的地方。如果省略，则序列将从
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<code class="parameter">offset</code> 开始一直到 <code class="parameter">array</code> 的末端。
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</p>
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</dd>
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<dt>
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<code class="parameter">preserve_keys</code></dt>
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<dd>
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<p class="para">
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注意 <span class="function"><strong>array_slice()</strong></span> 默认会重新排序并重置数组的数字索引。你可以通过将
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<code class="parameter">preserve_keys</code> 设为 <strong><code>TRUE</code></strong> 来改变此行为。
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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.array-slice-returnvalues">
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<h3 class="title">返回值</h3>
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<p class="para">
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返回其中一段。 如果 offset 参数大于 array 尺寸，就会返回空的 array。
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</p>
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</div>
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<div class="refsect1 changelog" id="refsect1-function.array-slice-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>5.2.4</td>
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<td>
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<code class="parameter">length</code> 参数默认值改成 <em>NULL</em>。
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现在 <code class="parameter">length</code> 为 <em>NULL</em> 时，意思是说使用 <code class="parameter">array</code> 的长度。
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之前的版本里， <em>NULL</em> 的 <code class="parameter">length</code>
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的意思是长度为零（啥也不返回）。
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</td>
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</tr>
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<tr>
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<td>5.0.2</td>
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<td>
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增加了可选参数 <code class="parameter">preserve_keys</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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</p>
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</div>
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<div class="refsect1 examples" id="refsect1-function.array-slice-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-6066">
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<p><strong>Example #1 <span class="function"><strong>array_slice()</strong></span> 例子</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 />$input </span><span style="color: #007700">= array(</span><span style="color: #DD0000">"a"</span><span style="color: #007700">, </span><span style="color: #DD0000">"b"</span><span style="color: #007700">, </span><span style="color: #DD0000">"c"</span><span style="color: #007700">, </span><span style="color: #DD0000">"d"</span><span style="color: #007700">, </span><span style="color: #DD0000">"e"</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">$output </span><span style="color: #007700">= </span><span style="color: #0000BB">array_slice</span><span style="color: #007700">(</span><span style="color: #0000BB">$input</span><span style="color: #007700">, </span><span style="color: #0000BB">2</span><span style="color: #007700">); </span><span style="color: #FF8000">// returns "c", "d", and "e"<br /></span><span style="color: #0000BB">$output </span><span style="color: #007700">= </span><span style="color: #0000BB">array_slice</span><span style="color: #007700">(</span><span style="color: #0000BB">$input</span><span style="color: #007700">, -</span><span style="color: #0000BB">2</span><span style="color: #007700">, </span><span style="color: #0000BB">1</span><span style="color: #007700">); </span><span style="color: #FF8000">// returns "d"<br /></span><span style="color: #0000BB">$output </span><span style="color: #007700">= </span><span style="color: #0000BB">array_slice</span><span style="color: #007700">(</span><span style="color: #0000BB">$input</span><span style="color: #007700">, </span><span style="color: #0000BB">0</span><span style="color: #007700">, </span><span style="color: #0000BB">3</span><span style="color: #007700">); </span><span style="color: #FF8000">// returns "a", "b", and "c"<br /><br />// note the differences in the array keys<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">array_slice</span><span style="color: #007700">(</span><span style="color: #0000BB">$input</span><span style="color: #007700">, </span><span style="color: #0000BB">2</span><span style="color: #007700">, -</span><span style="color: #0000BB">1</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">array_slice</span><span style="color: #007700">(</span><span style="color: #0000BB">$input</span><span style="color: #007700">, </span><span style="color: #0000BB">2</span><span style="color: #007700">, -</span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #0000BB">true</span><span style="color: #007700">));<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 class="example-contents"><p>以上例程会输出：</p></div>
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<div class="example-contents screen">
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<div class="cdata"><pre>
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Array
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(
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[0] => c
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[1] => d
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)
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Array
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(
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[2] => c
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[3] => d
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)
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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 seealso" id="refsect1-function.array-slice-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="array_splice.html" class="function" rel="rdfs-seeAlso">array_splice()</a> - 去掉数组中的某一部分并用其它值取代</span></li>
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<li class="member"><span class="function"><a href="unset.html" class="function" rel="rdfs-seeAlso">unset()</a> - 释放给定的变量</span></li>
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<li class="member"><span class="function"><a href="array_chunk.html" class="function" rel="rdfs-seeAlso">array_chunk()</a> - 将一个数组分割成多个</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> |