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166 lines
13 KiB
PHP
166 lines
13 KiB
PHP
<?php
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include_once __DIR__ . '/../../include/shared-manual.inc';
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$TOC = array();
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$PARENTS = array();
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include_once __DIR__ ."/toc/langref.inc";
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$setup = array (
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'home' =>
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array (
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0 => 'index.php',
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1 => 'PHP Manual',
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),
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'head' =>
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array (
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0 => 'UTF-8',
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1 => 'en',
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),
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'this' =>
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array (
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0 => 'language.exceptions.php',
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1 => 'Exceptions',
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),
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'up' =>
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array (
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0 => 'langref.php',
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1 => 'Language Reference',
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),
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'prev' =>
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array (
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0 => 'language.namespaces.faq.php',
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1 => 'FAQ: things you need to know about namespaces',
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),
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'next' =>
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array (
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0 => 'language.exceptions.extending.php',
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1 => 'Extending Exceptions',
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),
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'alternatives' =>
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array (
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),
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'extra_header_links' =>
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array (
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'rel' => 'alternate',
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'href' => '/manual/en/feeds/language.exceptions.atom',
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'type' => 'application/atom+xml',
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),
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);
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$setup["toc"] = $TOC;
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$setup["parents"] = $PARENTS;
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manual_setup($setup);
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manual_header();
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?>
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<div id="language.exceptions" class="chapter">
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<h1>Exceptions</h1>
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<h2>Table of Contents</h2><ul class="chunklist chunklist_chapter"><li><a href="language.exceptions.extending.php">Extending Exceptions</a></li></ul>
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<p class="para">
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PHP 5 has an exception model similar to that of other programming languages.
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An exception can be <em>throw</em>n, and caught
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("<em>catch</em>ed") within PHP. Code may be surrounded in a
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<em>try</em> block, to facilitate the catching of potential
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exceptions. Each <em>try</em> must have at least one
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corresponding <em>catch</em> block. Multiple
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<em>catch</em> blocks can be used to catch different classes of
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exceptions. Normal execution (when no exception is thrown within the
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<em>try</em> block, or when a <em>catch</em> matching
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the thrown exception's class is not present) will continue after that last
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<em>catch</em> block defined in sequence. Exceptions can be
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<em>throw</em>n (or re-thrown) within a <em>catch</em> block.
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</p>
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<p class="para">
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When an exception is thrown, code following the statement will not be
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executed, and PHP will attempt to find the first matching
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<em>catch</em> block. If an
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exception is not caught, a PHP Fatal Error will be issued with an
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"<em>Uncaught Exception ...</em>" message, unless a handler has
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been defined with <span class="function"><a href="function.set-exception-handler.php" class="function">set_exception_handler()</a></span>.
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</p>
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<p class="para">
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In PHP 5.5 and later, a <em>finally</em> block may also be
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specified after the <em>catch</em> blocks. Code within the
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<em>finally</em> block will always be executed after the
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<em>try</em> and <em>catch</em> blocks, regardless of
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whether an exception has been thrown, and before normal execution resumes.
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</p>
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<p class="para">
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The thrown object must be an instance of the <a href="class.exception.php" class="classname">Exception</a>
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class or a subclass of <a href="class.exception.php" class="classname">Exception</a>. Trying to throw an
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object that is not will result in a PHP Fatal Error.
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</p>
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<blockquote class="note"><p><strong class="note">Note</strong>:
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<p class="para">
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Internal PHP functions mainly use
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<a href="errorfunc.configuration.php#ini.error-reporting" class="link">Error reporting</a>, only modern
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<a href="language.oop5.php" class="link">Object oriented</a>
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extensions use exceptions. However, errors can be simply translated to
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exceptions with <a href="class.errorexception.php" class="link">ErrorException</a>.
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</p>
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</p></blockquote>
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<div class="tip"><strong class="tip">Tip</strong>
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<p class="para">
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The <a href="intro.spl.php" class="link">Standard PHP Library (SPL)</a> provides a
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good number of <a href="spl.exceptions.php" class="link">built-in exceptions</a>.
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</p>
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</div>
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<div class="example" id="example-269">
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<p><strong>Example #1 Throwing an Exception</strong></p>
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<div class="example-contents">
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<div class="phpcode"><code><span style="color: #000000">
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<span style="color: #0000BB"><?php<br></span><span style="color: #007700">function </span><span style="color: #0000BB">inverse</span><span style="color: #007700">(</span><span style="color: #0000BB">$x</span><span style="color: #007700">) {<br> if (!</span><span style="color: #0000BB">$x</span><span style="color: #007700">) {<br> throw new </span><span style="color: #0000BB">Exception</span><span style="color: #007700">(</span><span style="color: #DD0000">'Division by zero.'</span><span style="color: #007700">);<br> }<br> return </span><span style="color: #0000BB">1</span><span style="color: #007700">/</span><span style="color: #0000BB">$x</span><span style="color: #007700">;<br>}<br><br>try {<br> echo </span><span style="color: #0000BB">inverse</span><span style="color: #007700">(</span><span style="color: #0000BB">5</span><span style="color: #007700">) . </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br> echo </span><span style="color: #0000BB">inverse</span><span style="color: #007700">(</span><span style="color: #0000BB">0</span><span style="color: #007700">) . </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br>} catch (</span><span style="color: #0000BB">Exception $e</span><span style="color: #007700">) {<br> echo </span><span style="color: #DD0000">'Caught exception: '</span><span style="color: #007700">, </span><span style="color: #0000BB">$e</span><span style="color: #007700">-></span><span style="color: #0000BB">getMessage</span><span style="color: #007700">(), </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br>}<br><br></span><span style="color: #FF8000">// Continue execution<br></span><span style="color: #007700">echo </span><span style="color: #DD0000">"Hello World\n"</span><span style="color: #007700">;<br></span><span style="color: #0000BB">?></span>
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</span>
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</code></div>
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</div>
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<div class="example-contents"><p>The above example will output:</p></div>
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<div class="example-contents screen">
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<div class="cdata"><pre>
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0.2
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Caught exception: Division by zero.
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Hello World
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</pre></div>
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</div>
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</div>
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<div class="example" id="example-270">
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<p><strong>Example #2 Exception handling with a <em>finally</em> block</strong></p>
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<div class="example-contents">
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<div class="phpcode"><code><span style="color: #000000">
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<span style="color: #0000BB"><?php<br></span><span style="color: #007700">function </span><span style="color: #0000BB">inverse</span><span style="color: #007700">(</span><span style="color: #0000BB">$x</span><span style="color: #007700">) {<br> if (!</span><span style="color: #0000BB">$x</span><span style="color: #007700">) {<br> throw new </span><span style="color: #0000BB">Exception</span><span style="color: #007700">(</span><span style="color: #DD0000">'Division by zero.'</span><span style="color: #007700">);<br> }<br> return </span><span style="color: #0000BB">1</span><span style="color: #007700">/</span><span style="color: #0000BB">$x</span><span style="color: #007700">;<br>}<br><br>try {<br> echo </span><span style="color: #0000BB">inverse</span><span style="color: #007700">(</span><span style="color: #0000BB">5</span><span style="color: #007700">) . </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br>} catch (</span><span style="color: #0000BB">Exception $e</span><span style="color: #007700">) {<br> echo </span><span style="color: #DD0000">'Caught exception: '</span><span style="color: #007700">, </span><span style="color: #0000BB">$e</span><span style="color: #007700">-></span><span style="color: #0000BB">getMessage</span><span style="color: #007700">(), </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br>} </span><span style="color: #0000BB">finally </span><span style="color: #007700">{<br> echo </span><span style="color: #DD0000">"First finally.\n"</span><span style="color: #007700">;<br>}<br><br>try {<br> echo </span><span style="color: #0000BB">inverse</span><span style="color: #007700">(</span><span style="color: #0000BB">0</span><span style="color: #007700">) . </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br>} catch (</span><span style="color: #0000BB">Exception $e</span><span style="color: #007700">) {<br> echo </span><span style="color: #DD0000">'Caught exception: '</span><span style="color: #007700">, </span><span style="color: #0000BB">$e</span><span style="color: #007700">-></span><span style="color: #0000BB">getMessage</span><span style="color: #007700">(), </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br>} </span><span style="color: #0000BB">finally </span><span style="color: #007700">{<br> echo </span><span style="color: #DD0000">"Second finally.\n"</span><span style="color: #007700">;<br>}<br><br></span><span style="color: #FF8000">// Continue execution<br></span><span style="color: #007700">echo </span><span style="color: #DD0000">"Hello World\n"</span><span style="color: #007700">;<br></span><span style="color: #0000BB">?></span>
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</span>
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</code></div>
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</div>
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<div class="example-contents"><p>The above example will output:</p></div>
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<div class="example-contents screen">
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<div class="cdata"><pre>
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0.2
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First finally.
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Caught exception: Division by zero.
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Second finally.
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Hello World
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</pre></div>
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</div>
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</div>
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<div class="example" id="example-271">
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<p><strong>Example #3 Nested Exception</strong></p>
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<div class="example-contents">
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<div class="phpcode"><code><span style="color: #000000">
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<span style="color: #0000BB"><?php<br><br></span><span style="color: #007700">class </span><span style="color: #0000BB">MyException </span><span style="color: #007700">extends </span><span style="color: #0000BB">Exception </span><span style="color: #007700">{ }<br><br>class </span><span style="color: #0000BB">Test </span><span style="color: #007700">{<br> public function </span><span style="color: #0000BB">testing</span><span style="color: #007700">() {<br> try {<br> try {<br> throw new </span><span style="color: #0000BB">MyException</span><span style="color: #007700">(</span><span style="color: #DD0000">'foo!'</span><span style="color: #007700">);<br> } catch (</span><span style="color: #0000BB">MyException $e</span><span style="color: #007700">) {<br> </span><span style="color: #FF8000">// rethrow it<br> </span><span style="color: #007700">throw </span><span style="color: #0000BB">$e</span><span style="color: #007700">;<br> }<br> } catch (</span><span style="color: #0000BB">Exception $e</span><span style="color: #007700">) {<br> </span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$e</span><span style="color: #007700">-></span><span style="color: #0000BB">getMessage</span><span style="color: #007700">());<br> }<br> }<br>}<br><br></span><span style="color: #0000BB">$foo </span><span style="color: #007700">= new </span><span style="color: #0000BB">Test</span><span style="color: #007700">;<br></span><span style="color: #0000BB">$foo</span><span style="color: #007700">-></span><span style="color: #0000BB">testing</span><span style="color: #007700">();<br><br></span><span style="color: #0000BB">?></span>
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</span>
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</code></div>
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</div>
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<div class="example-contents"><p>The above example will output:</p></div>
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<div class="example-contents screen">
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<div class="cdata"><pre>
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string(4) "foo!"
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</pre></div>
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</div>
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</div>
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</div>
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<?php manual_footer(); ?>
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