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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>返回数组中指定的一列</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-column" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">array_column</h1>
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<p class="verinfo">(PHP 5 >= 5.5.0, PHP 7)</p><p class="refpurpose"><span class="refname">array_column</span> — <span class="dc-title">返回数组中指定的一列</span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.array-column-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_column</strong></span>
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( <span class="methodparam"><span class="type">array</span> <code class="parameter">$input</code></span>
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, <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$column_key</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">$index_key</code><span class="initializer"> = null</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_column()</strong></span>
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返回<code class="parameter">input</code>数组中键值为<code class="parameter">column_key</code>的列，
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如果指定了可选参数<code class="parameter">index_key</code>，那么<code class="parameter">input</code>数组中的这一列的值将作为返回数组中对应值的键。
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</p>
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</div>
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<div class="refsect1 parameters" id="refsect1-function.array-column-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">input</code></dt>
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<dd>
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<p class="para">
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需要取出数组列的多维数组。
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如果提供的是包含一组对象的数组，只有 public 属性会被直接取出。
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为了也能取出 private 和 protected 属性，类必须实现
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<span class="function"><strong>__get()</strong></span> 和 <span class="function"><strong>__isset()</strong></span> 魔术方法。
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</p>
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</dd>
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<dt>
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<code class="parameter">column_key</code></dt>
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<dd>
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<p class="para">
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需要返回值的列，它可以是索引数组的列索引，或者是关联数组的列的键，也可以是属性名。
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也可以是<strong><code>NULL</code></strong>，此时将返回整个数组（配合<code class="parameter">index_key</code>参数来重置数组键的时候，非常管用）
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</p>
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</dd>
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<dt>
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<code class="parameter">index_key</code></dt>
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<dd>
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<p class="para">
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作为返回数组的索引/键的列，它可以是该列的整数索引，或者字符串键值。
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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-column-returnvalues">
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<h3 class="title">返回值</h3>
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<p class="para">
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从多维数组中返回单列数组。
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</p>
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</div>
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<div class="refsect1 changelog" id="refsect1-function.array-column-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>7.0.0</td>
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<td>
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<code class="parameter">input</code> 参数现在可以是包含对象的数组。
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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-column-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-6013">
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<p><strong>Example #1 从结果集中取出first names列</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">// Array representing a possible record set returned from a database<br /></span><span style="color: #0000BB">$records </span><span style="color: #007700">= array(<br /> array(<br /> </span><span style="color: #DD0000">'id' </span><span style="color: #007700">=> </span><span style="color: #0000BB">2135</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">'first_name' </span><span style="color: #007700">=> </span><span style="color: #DD0000">'John'</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">'last_name' </span><span style="color: #007700">=> </span><span style="color: #DD0000">'Doe'</span><span style="color: #007700">,<br /> ),<br /> array(<br /> </span><span style="color: #DD0000">'id' </span><span style="color: #007700">=> </span><span style="color: #0000BB">3245</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">'first_name' </span><span style="color: #007700">=> </span><span style="color: #DD0000">'Sally'</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">'last_name' </span><span style="color: #007700">=> </span><span style="color: #DD0000">'Smith'</span><span style="color: #007700">,<br /> ),<br /> array(<br /> </span><span style="color: #DD0000">'id' </span><span style="color: #007700">=> </span><span style="color: #0000BB">5342</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">'first_name' </span><span style="color: #007700">=> </span><span style="color: #DD0000">'Jane'</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">'last_name' </span><span style="color: #007700">=> </span><span style="color: #DD0000">'Jones'</span><span style="color: #007700">,<br /> ),<br /> array(<br /> </span><span style="color: #DD0000">'id' </span><span style="color: #007700">=> </span><span style="color: #0000BB">5623</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">'first_name' </span><span style="color: #007700">=> </span><span style="color: #DD0000">'Peter'</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">'last_name' </span><span style="color: #007700">=> </span><span style="color: #DD0000">'Doe'</span><span style="color: #007700">,<br /> )<br />);<br /> <br /></span><span style="color: #0000BB">$first_names </span><span style="color: #007700">= </span><span style="color: #0000BB">array_column</span><span style="color: #007700">(</span><span style="color: #0000BB">$records</span><span style="color: #007700">, </span><span style="color: #DD0000">'first_name'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$first_names</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] => John
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[1] => Sally
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[2] => Jane
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[3] => Peter
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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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<p class="para">
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<div class="example" id="example-6014">
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<p><strong>Example #2
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从结果集中总取出last names列，用相应的id作为键值
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</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">// Using the $records array from Example #1<br /></span><span style="color: #0000BB">$last_names </span><span style="color: #007700">= </span><span style="color: #0000BB">array_column</span><span style="color: #007700">(</span><span style="color: #0000BB">$records</span><span style="color: #007700">, </span><span style="color: #DD0000">'last_name'</span><span style="color: #007700">, </span><span style="color: #DD0000">'id'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$last_names</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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[2135] => Doe
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[3245] => Smith
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[5342] => Jones
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[5623] => Doe
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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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<p class="para">
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<div class="example" id="example-6015">
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<p><strong>Example #3
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username 列是从对象获取 public 的 "username" 属性
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</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 /><br /></span><span style="color: #007700">class </span><span style="color: #0000BB">User<br /></span><span style="color: #007700">{<br /> public </span><span style="color: #0000BB">$username</span><span style="color: #007700">;<br /><br /> public function </span><span style="color: #0000BB">__construct</span><span style="color: #007700">(</span><span style="color: #0000BB">string $username</span><span style="color: #007700">)<br /> {<br /> </span><span style="color: #0000BB">$this</span><span style="color: #007700">-></span><span style="color: #0000BB">username </span><span style="color: #007700">= </span><span style="color: #0000BB">$username</span><span style="color: #007700">;<br /> }<br />}<br /><br /></span><span style="color: #0000BB">$users </span><span style="color: #007700">= [<br /> new </span><span style="color: #0000BB">User</span><span style="color: #007700">(</span><span style="color: #DD0000">'user 1'</span><span style="color: #007700">),<br /> new </span><span style="color: #0000BB">User</span><span style="color: #007700">(</span><span style="color: #DD0000">'user 2'</span><span style="color: #007700">),<br /> new </span><span style="color: #0000BB">User</span><span style="color: #007700">(</span><span style="color: #DD0000">'user 3'</span><span style="color: #007700">),<br />];<br /><br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">array_column</span><span style="color: #007700">(</span><span style="color: #0000BB">$users</span><span style="color: #007700">, </span><span style="color: #DD0000">'username'</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] => user 1
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[1] => user 2
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[2] => user 3
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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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<p class="para">
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<div class="example" id="example-6016">
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<p><strong>Example #4
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获取 username 列，从对象通过魔术方法 <span class="function"><strong>__get()</strong></span> 获取 private 的 "username" 属性。
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</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 /><br /></span><span style="color: #007700">class </span><span style="color: #0000BB">Person<br /></span><span style="color: #007700">{<br /> private </span><span style="color: #0000BB">$name</span><span style="color: #007700">;<br /><br /> public function </span><span style="color: #0000BB">__construct</span><span style="color: #007700">(</span><span style="color: #0000BB">string $name</span><span style="color: #007700">)<br /> {<br /> </span><span style="color: #0000BB">$this</span><span style="color: #007700">-></span><span style="color: #0000BB">name </span><span style="color: #007700">= </span><span style="color: #0000BB">$name</span><span style="color: #007700">;<br /> }<br /><br /> public function </span><span style="color: #0000BB">__get</span><span style="color: #007700">(</span><span style="color: #0000BB">$prop</span><span style="color: #007700">)<br /> {<br /> return </span><span style="color: #0000BB">$this</span><span style="color: #007700">-></span><span style="color: #0000BB">$prop</span><span style="color: #007700">;<br /> }<br /><br /> public function </span><span style="color: #0000BB">__isset</span><span style="color: #007700">(</span><span style="color: #0000BB">$prop</span><span style="color: #007700">) : </span><span style="color: #0000BB">bool<br /> </span><span style="color: #007700">{<br /> return isset(</span><span style="color: #0000BB">$this</span><span style="color: #007700">-></span><span style="color: #0000BB">$prop</span><span style="color: #007700">);<br /> }<br />}<br /><br /></span><span style="color: #0000BB">$people </span><span style="color: #007700">= [<br /> new </span><span style="color: #0000BB">Person</span><span style="color: #007700">(</span><span style="color: #DD0000">'Fred'</span><span style="color: #007700">),<br /> new </span><span style="color: #0000BB">Person</span><span style="color: #007700">(</span><span style="color: #DD0000">'Jane'</span><span style="color: #007700">),<br /> new </span><span style="color: #0000BB">Person</span><span style="color: #007700">(</span><span style="color: #DD0000">'John'</span><span style="color: #007700">),<br />];<br /><br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">array_column</span><span style="color: #007700">(</span><span style="color: #0000BB">$people</span><span style="color: #007700">, </span><span style="color: #DD0000">'name'</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] => Fred
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[1] => Jane
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[2] => John
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)
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</pre></div>
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</div>
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</div>
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如果不提供<span class="function"><strong>__isset()</strong></span>，会返回空数组。
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</p>
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</div>
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<div class="refsect1 seealso" id="refsect1-function.array-column-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">
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<a href="https://github.com/ramsey/array_column/blob/master/src/array_column.php" class="link external">» Recommended
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userland implementation for PHP lower than 5.5</a>
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</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> |