reset.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- EN-Revision: 0a192fcd9cc43c0007de795063b4494974058992 Maintainer: dallas Status: ready -->
<refentry xml:id="function.reset" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>reset</refname>
  <refpurpose>将数组的内部指针指向第一个单元</refpurpose>
 </refnamediv>
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>mixed</type><methodname>reset</methodname>
   <methodparam><type class="union"><type>array</type><type>object</type></type><parameter role="reference">array</parameter></methodparam>
  </methodsynopsis>
  <para>
   <function>reset</function> 将 <parameter>array</parameter>
   的内部指针倒回到第一个单元并返回第一个数组单元的值。
  </para>
 </refsect1>
 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>array</parameter></term>
     <listitem>
      <para>
       输入的数组。
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>
 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   返回数组第一个单元的值，如果数组为空则返回 &false;。
  </para>
  &return.falseproblem;
 </refsect1>
 <refsect1 role="changelog">
  &reftitle.changelog;
  <informaltable>
   <tgroup cols="2">
    <thead>
     <row>
      <entry>&Version;</entry>
      <entry>&Description;</entry>
     </row>
    </thead>
    <tbody>
     &standard.changelog.calling-on-objects;
    </tbody>
   </tgroup>
  </informaltable>
 </refsect1>
 
 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>reset</function> 例子</title>
    <programlisting role="php">
<![CDATA[
<?php

$array = array('step one', 'step two', 'step three', 'step four');

// 默认情况下，指针指向第一个元素
echo current($array) . "<br />\n"; // "step one"

// 跳过两步
next($array);
next($array);
echo current($array) . "<br />\n"; // "step three"

// 重置指针，重新指向第一个元素
reset($array);
echo current($array) . "<br />\n"; // "step one"

?>
]]>
    </programlisting>
   </example>
  </para>
 </refsect1>
 <refsect1 role="notes">
  &reftitle.notes;
  <note>
   <simpara>
    返回的值无法区分是空数组，还是第一个元素是 <type>bool</type> &false;。
    要正确检测数组第一个元素包含 &false; 的情况，首先要检测数组 <function>count</function>，
    或在调用 <function>reset</function> 后检测 <function>key</function> 不为 &null;。
   </simpara>
  </note>
 </refsect1>
 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>current</function></member>
    <member><function>each</function></member>
    <member><function>end</function></member>
    <member><function>next</function></member>
    <member><function>prev</function></member>
    <member><function>array_key_first</function></member>
   </simplelist>
  </para>
 </refsect1>
</refentry>

<!-- Keep this comment at the end of the file
Local variables:
mode: sgml
sgml-omittag:t
sgml-shorttag:t
sgml-minimize-attributes:nil
sgml-always-quote-attributes:t
sgml-indent-step:1
sgml-indent-data:t
indent-tabs-mode:nil
sgml-parent-document:nil
sgml-default-dtd-file:"~/.phpdoc/manual.ced"
sgml-exposed-tags:nil
sgml-local-catalogs:nil
sgml-local-ecat-files:nil
End:
vim600: syn=xml fen fdm=syntax fdl=2 si
vim: et tw=78 syn=sgml
vi: ts=1 sw=1
-->