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<title>Backward Incompatible Changes</title>
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</div><hr /><div id="migration55.incompatible" class="sect1">
<h2 class="title">Backward Incompatible Changes</h2>
<p class="simpara">
Although most existing PHP 5 code should work without changes, please take
note of some backward incompatible changes:
</p>
<div class="sect2" id="migration55.incompatible.windows">
<h3 class="title">Windows XP and 2003 support dropped</h3>
<p class="para">
Support for Windows XP and 2003 has been dropped. Windows builds of PHP
now require Windows Vista or newer.
</p>
</div>
<div class="sect2" id="migration55.incompatible.case">
<h3 class="title">Case insensitivity no longer locale specific</h3>
<p class="para">
All case insensitive matching for function, class and constant names is
now performed in a locale independent manner according to ASCII rules.
This improves support for languages using the Latin alphabet with unusual
collating rules, such as Turkish and Azeri.
</p>
<p class="para">
This may cause issues for code that uses case insensitive matches for
non-ASCII characters in multibyte character sets (including UTF-8), such
as accented characters in many European languages. If you have a
non-English, non-ASCII code base, then you will need to test that you are
not inadvertently relying on this behaviour before deploying PHP 5.5 to
production systems.
</p>
</div>
<div class="sect2" id="migration55.incompatible.pack">
<h3 class="title"> <span class="function"><a href="function.pack.html" class="function">pack()</a></span> and <span class="function"><a href="function.unpack.html" class="function">unpack()</a></span> changes</h3>
<p class="para">
Changes were made to <span class="function"><a href="function.pack.html" class="function">pack()</a></span> and
<span class="function"><a href="function.unpack.html" class="function">unpack()</a></span> to make them more compatible with Perl:
</p>
<ul class="itemizedlist">
<li class="listitem">
<span class="simpara">
<span class="function"><a href="function.pack.html" class="function">pack()</a></span> now supports the "Z" format code, which
behaves identically to "a".
</span>
</li>
<li class="listitem">
<span class="simpara">
<span class="function"><a href="function.unpack.html" class="function">unpack()</a></span> now support the "Z" format code for NULL
padded strings, and behaves as "a" did in previous versions: it will
strip trailing NULL bytes.
</span>
</li>
<li class="listitem">
<span class="simpara">
<span class="function"><a href="function.unpack.html" class="function">unpack()</a></span> now keeps trailing NULL bytes when the "a"
format code is used.
</span>
</li>
<li class="listitem">
<span class="simpara">
<span class="function"><a href="function.unpack.html" class="function">unpack()</a></span> now strips all trailing ASCII whitespace
when the "A" format code is used.
</span>
</li>
</ul>
<p class="para">
Writing backward compatible code that uses the "a" format code with
<span class="function"><a href="function.unpack.html" class="function">unpack()</a></span> requires the use of
<span class="function"><a href="function.version-compare.html" class="function">version_compare()</a></span>, due to the backward compatibility
break.
</p>
<p class="para">
For example:
</p>
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// Old code:<br /></span><span style="color: #0000BB">$data </span><span style="color: #007700">= </span><span style="color: #0000BB">unpack</span><span style="color: #007700">(</span><span style="color: #DD0000">'a5'</span><span style="color: #007700">, </span><span style="color: #0000BB">$packed</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// New code:<br /></span><span style="color: #007700">if (</span><span style="color: #0000BB">version_compare</span><span style="color: #007700">(</span><span style="color: #0000BB">PHP_VERSION</span><span style="color: #007700">, </span><span style="color: #DD0000">'5.5.0-dev'</span><span style="color: #007700">, </span><span style="color: #DD0000">'>='</span><span style="color: #007700">)) {<br /> </span><span style="color: #0000BB">$data </span><span style="color: #007700">= </span><span style="color: #0000BB">unpack</span><span style="color: #007700">(</span><span style="color: #DD0000">'Z5'</span><span style="color: #007700">, </span><span style="color: #0000BB">$packed</span><span style="color: #007700">);<br />} else {<br /> </span><span style="color: #0000BB">$data </span><span style="color: #007700">= </span><span style="color: #0000BB">unpack</span><span style="color: #007700">(</span><span style="color: #DD0000">'a5'</span><span style="color: #007700">, </span><span style="color: #0000BB">$packed</span><span style="color: #007700">);<br />}<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</div>
<div class="sect2" id="migration55.incompatible.self-parent-static">
<h3 class="title"><em>self</em>, <em>parent</em> and <em>static</em> are now always case insensitive</h3>
<p class="para">
Prior to PHP 5.5, cases existed where the
<a href="language.oop5.paamayim-nekudotayim.html" class="link">self</a>,
<a href="language.oop5.paamayim-nekudotayim.html" class="link">parent</a>, and
<a href="language.oop5.late-static-bindings.html" class="link">static</a>
keywords were treated in a case sensitive fashion. These have now been
resolved, and these keywords are always handled case insensitively:
<em>SELF::CONSTANT</em> is now treated identically to
<em>self::CONSTANT</em>.
</p>
</div>
<div class="sect2" id="migration55.incompatible.guid">
<h3 class="title">PHP logo GUIDs removed</h3>
<p class="para">
The GUIDs that previously resulted in PHP outputting various logos have
been removed. This includes the removal of the functions to return those
GUIDs. The removed functions are:
</p>
<ul class="itemizedlist">
<li class="listitem">
<span class="simpara">
<span class="function"><a href="function.php-logo-guid.html" class="function">php_logo_guid()</a></span>
</span>
</li>
<li class="listitem">
<span class="simpara">
<span class="function"><strong>php_egg_logo_guid()</strong></span>
</span>
</li>
<li class="listitem">
<span class="simpara">
<span class="function"><strong>php_real_logo_guid()</strong></span>
</span>
</li>
<li class="listitem">
<span class="simpara">
<span class="function"><a href="function.zend-logo-guid.html" class="function">zend_logo_guid()</a></span>
</span>
</li>
</ul>
</div>
<div class="sect2" id="migration55.incompatible.execution">
<h3 class="title">Internal execution changes</h3>
<p class="para">
Extension authors should note that the <strong class="command">zend_execute()</strong>
function can no longer be overridden, and that numerous changes have been
made to the <em>execute_data</em> struct and related function
and method handling opcodes.
</p>
<p class="para">
Most extension authors are unlikely to be affected, but those writing
extensions that hook deeply into the Zend Engine should read
<a href="migration55.internals.html" class="link">the notes on these changes</a>.
</p>
</div>
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