mirror of
https://github.com/sigmasternchen/php-doc-en
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87 lines
2.5 KiB
XML
87 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.else" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
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<title>else</title>
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<?phpdoc print-version-for="else"?>
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<para>
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Often you'd want to execute a statement if a certain condition is
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met, and a different statement if the condition is not met. This
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is what <literal>else</literal> is for. <literal>else</literal>
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extends an <literal>if</literal> statement to execute a statement
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in case the expression in the <literal>if</literal> statement
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evaluates to &false;. For example, the following
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code would display <computeroutput>a is greater than
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b</computeroutput> if <varname>$a</varname> is greater than
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<varname>$b</varname>, and <computeroutput>a is NOT greater
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than b</computeroutput> otherwise:
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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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if ($a > $b) {
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echo "a is greater than b";
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} else {
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echo "a is NOT greater than b";
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}
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?>
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]]>
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</programlisting>
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</informalexample>
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The <literal>else</literal> statement is only executed if the
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<literal>if</literal> expression evaluated to
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&false;, and if there were any
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<literal>elseif</literal> expressions - only if they evaluated to
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&false; as well (see <link
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linkend="control-structures.elseif">elseif</link>).
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</para>
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<note>
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<title>Dangling else</title>
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<para>
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In case of nested <literal>if</literal>-<literal>else</literal> statements,
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an <literal>else</literal> is always associated with the nearest <literal>if</literal>.
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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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$a = false;
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$b = true;
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if ($a)
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if ($b)
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echo "b";
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else
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echo "c";
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?>
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]]>
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</programlisting>
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</informalexample>
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Despite the indentation (which does not matter for PHP), the <literal>else</literal>
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is associated with the <literal>if ($b)</literal>, so the example does not produce
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any output. While relying on this behavior is valid, it is recommended to avoid
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it by using curly braces to resolve potential ambiguities.
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</para>
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</note>
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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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