archived-doc-zh/reference/array/functions/array-column.xml

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<refentry xml:id="function.array-column" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>array_column</refname>
  <refpurpose>返回数组中指定的一列</refpurpose>
 </refnamediv>
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>array</type><methodname>array_column</methodname>
   <methodparam><type>array</type><parameter>input</parameter></methodparam>
   <methodparam><type>mixed</type><parameter>column_key</parameter></methodparam>
   <methodparam choice="opt"><type>mixed</type><parameter>index_key</parameter></methodparam>
  </methodsynopsis>
  <para>
   <function>array_column</function>
   返回<parameter>input</parameter>数组中键值为<parameter>column_key</parameter>的列，
   如果指定了可选参数<parameter>index_key</parameter>，那么<parameter>input</parameter>数组中的这一列的值将作为返回数组中对应值的键。
  </para>
 </refsect1>
 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>input</parameter></term>
     <listitem>
      <para>
       需要取出数组列的多维数组（或结果集）
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>column_key</parameter></term>
     <listitem>
      <para>
       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&null;，此时将返回整个数组（配合<parameter>index_key</parameter>参数来重置数组键的时候，非常管用）
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>index_key</parameter></term>
     <listitem>
      <para>
       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。
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>
 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   从多维数组中返回单列数组
  </para>
 </refsect1>
 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title>从结果集中取出first names列</title>
    <programlisting role="php">
<![CDATA[
<?php
// Array representing a possible record set returned from a database
$records = array(
    array(
        'id' => 2135,
        'first_name' => 'John',
        'last_name' => 'Doe',
    ),
    array(
        'id' => 3245,
        'first_name' => 'Sally',
        'last_name' => 'Smith',
    ),
    array(
        'id' => 5342,
        'first_name' => 'Jane',
        'last_name' => 'Jones',
    ),
    array(
        'id' => 5623,
        'first_name' => 'Peter',
        'last_name' => 'Doe',
    )
);
 
$first_names = array_column($records, 'first_name');
print_r($first_names);
?>
]]>
    </programlisting>
    &example.outputs;
    <screen role="php">
<![CDATA[
Array
(
    [0] => John
    [1] => Sally
    [2] => Jane
    [3] => Peter
)
]]>
    </screen>
   </example>
  </para>
  <para>
   <example>
    <title>
     从结果集中总取出last names列，用相应的id作为键值
    </title>
    <programlisting role="php">
<![CDATA[
<?php
// Using the $records array from Example #1
$last_names = array_column($records, 'last_name', 'id');
print_r($last_names);
?>
]]>
    </programlisting>
    &example.outputs;
    <screen role="php">
<![CDATA[
Array
(
    [2135] => Doe
    [3245] => Smith
    [5342] => Jones
    [5623] => Doe
)
]]>
    </screen>
   </example>
  </para>
 </refsect1>
</refentry>

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