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7104ee97ce
Closes GH-250. git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@351935 c90b9560-bf6c-de11-be94-00142212c4b1
98 lines
2.5 KiB
XML
98 lines
2.5 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
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<!-- $Revision$ -->
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<sect1 xml:id="control-structures.while" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
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<title>while</title>
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<?phpdoc print-version-for="while"?>
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<para>
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<literal>while</literal> loops are the simplest type of loop in
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PHP. They behave just like their C counterparts. The basic form
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of a <literal>while</literal> statement is:
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<informalexample>
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<programlisting>
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<![CDATA[
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while (expr)
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statement
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]]>
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</programlisting>
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</informalexample>
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</para>
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<simpara>
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The meaning of a <literal>while</literal> statement is simple. It
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tells PHP to execute the nested statement(s) repeatedly, as long
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as the <literal>while</literal> expression evaluates to
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&true;. The value of the expression is checked
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each time at the beginning of the loop, so even if this value
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changes during the execution of the nested statement(s), execution
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will not stop until the end of the iteration (each time PHP runs
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the statements in the loop is one iteration). If the
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<literal>while</literal> expression evaluates to
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&false; from the very beginning, the nested
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statement(s) won't even be run once.
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</simpara>
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<para>
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Like with the <literal>if</literal> statement, you can group
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multiple statements within the same <literal>while</literal> loop
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by surrounding a group of statements with curly braces, or by
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using the alternate syntax:
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<informalexample>
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<programlisting>
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<![CDATA[
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while (expr):
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statement
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...
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endwhile;
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]]>
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</programlisting>
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</informalexample>
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</para>
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<para>
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The following examples are identical, and both print the numbers
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1 through 10:
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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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/* example 1 */
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$i = 1;
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while ($i <= 10) {
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echo $i++; /* the printed value would be
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$i before the increment
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(post-increment) */
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}
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/* example 2 */
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$i = 1;
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while ($i <= 10):
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echo $i;
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$i++;
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endwhile;
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?>
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]]>
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</programlisting>
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</informalexample>
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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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