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<h1>Exceptions</h1>
<h2>Table of Contents</h2><ul class="chunklist chunklist_chapter"><li><a href="language.exceptions.extending.html">Extending Exceptions</a></li></ul>
<p class="para">
PHP 5 has an exception model similar to that of other programming languages.
An exception can be <em>throw</em>n, and caught
("<em>catch</em>ed") within PHP. Code may be surrounded in a
<em>try</em> block, to facilitate the catching of potential
exceptions. Each <em>try</em> must have at least one
corresponding <em>catch</em> block. Multiple
<em>catch</em> blocks can be used to catch different classes of
exceptions. Normal execution (when no exception is thrown within the
<em>try</em> block, or when a <em>catch</em> matching
the thrown exception's class is not present) will continue after that last
<em>catch</em> block defined in sequence. Exceptions can be
<em>throw</em>n (or re-thrown) within a <em>catch</em> block.
</p>
<p class="para">
When an exception is thrown, code following the statement will not be
executed, and PHP will attempt to find the first matching
<em>catch</em> block. If an
exception is not caught, a PHP Fatal Error will be issued with an
"<em>Uncaught Exception ...</em>" message, unless a handler has
been defined with <span class="function"><a href="function.set-exception-handler.html" class="function">set_exception_handler()</a></span>.
</p>
<p class="para">
In PHP 5.5 and later, a <em>finally</em> block may also be
specified after the <em>catch</em> blocks. Code within the
<em>finally</em> block will always be executed after the
<em>try</em> and <em>catch</em> blocks, regardless of
whether an exception has been thrown, and before normal execution resumes.
</p>
<p class="para">
The thrown object must be an instance of the <a href="class.exception.html" class="classname">Exception</a>
class or a subclass of <a href="class.exception.html" class="classname">Exception</a>. Trying to throw an
object that is not will result in a PHP Fatal Error.
</p>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
Internal PHP functions mainly use
<a href="errorfunc.configuration.html#ini.error-reporting" class="link">Error reporting</a>, only modern
<a href="language.oop5.html" class="link">Object oriented</a>
extensions use exceptions. However, errors can be simply translated to
exceptions with <a href="class.errorexception.html" class="link">ErrorException</a>.
</p>
</p></blockquote>
<div class="tip"><strong class="tip">Tip</strong>
<p class="para">
The <a href="intro.spl.html" class="link">Standard PHP Library (SPL)</a> provides a
good number of <a href="spl.exceptions.html" class="link">built-in exceptions</a>.
</p>
</div>
<div class="example" id="example-269">
<p><strong>Example #1 Throwing an Exception</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<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>
</span>
</code></div>
</div>
<div class="example-contents"><p>The above example will output:</p></div>
<div class="example-contents screen">
<div class="cdata"><pre>
0.2
Caught exception: Division by zero.
Hello World
</pre></div>
</div>
</div>
<div class="example" id="example-270">
<p><strong>Example #2 Exception handling with a <em>finally</em> block</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<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>
</span>
</code></div>
</div>
<div class="example-contents"><p>The above example will output:</p></div>
<div class="example-contents screen">
<div class="cdata"><pre>
0.2
First finally.
Caught exception: Division by zero.
Second finally.
Hello World
</pre></div>
</div>
</div>
<div class="example" id="example-271">
<p><strong>Example #3 Nested Exception</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<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>
</span>
</code></div>
</div>
<div class="example-contents"><p>The above example will output:</p></div>
<div class="example-contents screen">
<div class="cdata"><pre>
string(4) "foo!"
</pre></div>
</div>
</div>
</div>
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