mirror of
https://github.com/php/doc-zh.git
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165 lines
3.5 KiB
XML
165 lines
3.5 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
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<!-- $Revision$ -->
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<!-- EN-Revision: 16389a7b31069481d6c8c0705172bee5ef1ddf5f Maintainer: dallas Status: ready -->
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<!-- CREDITS: mowangjuanzi -->
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<sect1 xml:id="control-structures.continue" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
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<title>continue</title>
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<?phpdoc print-version-for="continue"?>
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<simpara>
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<literal>continue</literal>
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在循环结构用用来跳过本次循环中剩余的代码并在条件求值为真时开始执行下一次循环。
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</simpara>
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<note>
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<simpara>
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在 PHP 中
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<link linkend="control-structures.switch">switch</link>
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语句被认为是可以使用 <literal>continue</literal> 的一种循环结构。
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<literal>continue</literal> 的行为类似于没有传递参数的
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<literal>break</literal> ，但会引发警告，因为这可能是一个错误。
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如果 <literal>switch</literal> 在循环内，
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<literal>continue 2</literal> 将会外部循环中的下一个迭代中继续。
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</simpara>
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</note>
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<simpara>
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<literal>continue</literal> 接受一个可选的数字参数来决定跳过几重循环到循环结尾。默认值是
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<literal>1</literal>，即跳到当前循环末尾。
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</simpara>
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<para>
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<informalexample>
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<programlisting role="php">
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<![CDATA[
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<?php
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$arr = ['zero', 'one', 'two', 'three', 'four', 'five', 'six'];
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foreach ($arr as $key => $value) {
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if (0 === ($key % 2)) { // 跳过偶数键的成员
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continue;
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}
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echo $value . "\n";
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}
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?>
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]]>
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</programlisting>
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&examples.outputs;
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<screen>
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<![CDATA[
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one
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three
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five
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]]>
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</screen>
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<programlisting role="php">
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<![CDATA[
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<?php
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$i = 0;
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while ($i++ < 5) {
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echo "Outer\n";
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while (1) {
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echo "Middle\n";
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while (1) {
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echo "Inner\n";
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continue 3;
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}
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echo "This never gets output.\n";
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}
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echo "Neither does this.\n";
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}
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?>
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]]>
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</programlisting>
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&examples.outputs;
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<screen>
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<![CDATA[
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Outer
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Middle
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Inner
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Outer
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Middle
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Inner
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Outer
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Middle
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Inner
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Outer
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Middle
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Inner
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Outer
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Middle
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Inner
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]]>
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</screen>
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</informalexample>
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</para>
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<para>
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省略 <literal>continue</literal>
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后面的分号会导致混淆。以下例子示意了不应该这样做。
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</para>
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<para>
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<informalexample>
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<programlisting role="php">
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<![CDATA[
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<?php
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for ($i = 0; $i < 5; ++$i) {
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if ($i == 2)
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continue
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print "$i\n";
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}
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?>
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]]>
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</programlisting>
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<para>
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希望得到的结果是：
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</para>
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<screen>
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<![CDATA[
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0
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1
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3
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4
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]]>
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</screen>
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</informalexample>
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</para>
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<para>
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<table>
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<title><literal>continue</literal> 的更新记录</title>
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<tgroup cols="2">
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<thead>
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<row>
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<entry>&Version;</entry>
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<entry>&Description;</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry>7.3.0</entry>
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<entry>
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在 <literal>switch</literal> 中 <literal>continue</literal> 语句试图代替 <literal>break</literal>
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语句将会触发 <constant>E_WARNING</constant> 。
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</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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</para>
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</sect1>
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<!-- Keep this comment at the end of the file
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Local variables:
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mode: sgml
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sgml-omittag:t
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sgml-shorttag:t
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sgml-minimize-attributes:nil
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sgml-always-quote-attributes:t
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sgml-indent-step:1
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sgml-indent-data:t
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indent-tabs-mode:nil
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sgml-parent-document:nil
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sgml-default-dtd-file:"~/.phpdoc/manual.ced"
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sgml-exposed-tags:nil
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sgml-local-catalogs:nil
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sgml-local-ecat-files:nil
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End:
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vim600: syn=xml fen fdm=syntax fdl=2 si
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vim: et tw=78 syn=sgml
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vi: ts=1 sw=1
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-->
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