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<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<sect1 xml:id="control-structures.goto" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
<title>goto</title>
<?phpdoc print-version-for="goto"?>
<para>
What's the worse thing that could happen if you use goto (xkcd URL)?
<link xlink:href="&url.xkcd;292">xkcd</link>
</para>
<para>
The <literal>goto</literal> operator can be used to jump to another
section in the program. The target point is specified by a <emphasis>case-sensitive</emphasis> label
followed by a colon, and the instruction is given as
<literal>goto</literal> followed by the desired target label. This
is not a full unrestricted <literal>goto</literal>. The target
label must be within the same file and context, meaning that you cannot jump
out of a function or method, nor can you jump into one. You also
cannot jump into any sort of loop or switch structure. You may jump
out of these, and a common use is to use a <literal>goto</literal>
in place of a multi-level <literal>break</literal>.
</para>
<para>
<example>
<title><literal>goto</literal> example</title>
<programlisting role="php">
<![CDATA[
<?php
goto a;
echo 'Foo';
a:
echo 'Bar';
?>
]]>
</programlisting>
&example.outputs;
<screen>
<![CDATA[
Bar
]]>
</screen>
</example>
</para>
<para>
<example>
<title><literal>goto</literal> loop example</title>
<programlisting role="php">
<![CDATA[
<?php
for ($i = 0, $j = 50; $i < 100; $i++) {
while ($j--) {
if ($j == 17) {
goto end;
}
}
}
echo "i = $i";
end:
echo 'j hit 17';
?>
]]>
</programlisting>
&example.outputs;
<screen>
<![CDATA[
j hit 17
]]>
</screen>
</example>
</para>
<para>
<example>
<title>This will not work</title>
<programlisting role="php">
<![CDATA[
<?php
goto loop;
for ($i = 0, $j = 50; $i < 100; $i++) {
while ($j--) {
loop:
}
}
echo "$i = $i";
?>
]]>
</programlisting>
&example.outputs;
<screen>
<![CDATA[
Fatal error: 'goto' into loop or switch statement is disallowed in
script on line 2
]]>
</screen>
</example>
</para>
</sect1>
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sgml-shorttag:t
sgml-minimize-attributes:nil
sgml-always-quote-attributes:t
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sgml-parent-document:nil
sgml-default-dtd-file:"~/.phpdoc/manual.ced"
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End:
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vim: et tw=78 syn=sgml
vi: ts=1 sw=1
-->
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