<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision: 330933 $ -->
<appendix xml:id="migration51" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
 <title>Migrating from PHP 5.0.x to PHP 5.1.x</title>
 <para>
  &manual.migration.seealso;
  <link linkend="migration5">5.0.x</link>, 
  <link linkend="migration52">5.2.x</link>,
  <link linkend="migration53">5.3.x</link>,
  <link linkend="migration54">5.4.x</link> and
  <link linkend="migration55">5.5.x</link>.
 </para>

 <section xml:id="migration51.changes">
  <title>Key PHP 5.1.x features</title>
  <para>
   Some of the key features of PHP 5.1.x include:
  </para>
  <itemizedlist>
   <listitem>
    <para>
     A complete rewrite of date handling code, with improved timezone support.
    </para>
   </listitem>
   <listitem>
    <para>
     Significant performance improvements compared to PHP 5.0.X.
    </para>
   </listitem>
   <listitem>
    <para>
     PDO extension is now enabled by default.
    </para>
   </listitem>
   <listitem>
    <para>
     Over 30 new functions in various extensions and built-in functionality.
    </para>
   </listitem>
   <listitem>
    <para>
     Over 400 various bug fixes.
    </para>
   </listitem>
  </itemizedlist>
 </section>

 <section xml:id="migration51.references">
  <title>Changes in reference handling</title>
  <itemizedlist>
   <listitem>
    <para>
     <link linkend="migration51.references-overview">Overview</link>
    </para>
   </listitem>
   <listitem>
    <para>
     <link linkend="migration51.references-fails">Code that worked under PHP
      4.3.x, but now fails</link>
    </para>
   </listitem>
   <listitem>
    <para>
     <link linkend="migration51.references-error">Code that worked under PHP
      4.3.x, but now throws an error</link>
    </para>
   </listitem>
   <listitem>
    <para>
     <link linkend="migration51.references-works">Code that failed under PHP
      4.3.x, but now works</link>
    </para>
   </listitem>
   <listitem>
    <para>
     <link linkend="migration51.references-didnotwork">Code that
      should have worked under PHP 5.0.x</link>
    </para>
   </listitem>
   <listitem>
    <para>
     <link linkend="migration51.references-warnings">Warnings that came and
      went</link>
    </para>
   </listitem>
  </itemizedlist>

  <section xml:id="migration51.references-overview">
   <title>Overview</title>
   <para>
    From the PHP script writer's point of view, the change most likely to
    impact legacy code is in the way that references are handled in all PHP
    versions post-dating the PHP 4.4.0 release.
   </para>
   <para>
    Until and including PHP 4.3, it was possible to send, assign or return
    variables by reference that should really be returned by value, such as
    a constant, a temporary value (e.g. the result of an expression), or the
    result of a function that had itself been returned by value, as here:
   </para>
   <informalexample>
    <programlisting role="php">
<![CDATA[
<?php
$foo = "123";

function return_value() {
    global $foo;
    return $foo;
}

$bar = &return_value();
?>
]]>
    </programlisting>
   </informalexample>
   <para>
    Although this code would usually work as expected under PHP 4.3, in the
    general case the result is undefined. The Zend Engine could not act
    correctly on these values as references. This bug could and did lead to
    various hard-to-reproduce memory corruption problems, particularly
    where the code base was large.
   </para>
   <para>
    In PHP 4.4.0, PHP 5.0.4 and all subsequent PHP releases, the Engine was
    fixed to 'know' when the reference operation is being used on a value
    that should not be referenced. The actual value is now used in such
    cases, and a warning is emitted. The warning takes the form of an
    <constant>E_NOTICE</constant> in PHP 4.4.0 and up, and
    <constant>E_STRICT</constant> in PHP 5.0.4 and up.
   </para>
   <para>
    Code that could potentially produce memory corruption can no longer do
    so. However, some legacy code might work differently as a result.
   </para>
  </section>

  <section xml:id="migration51.references-fails">
   <title>Code that worked under PHP 4.3, but now fails</title>
   <informalexample>
    <programlisting role="php">
<![CDATA[
<?php
function func(&$arraykey) {
    return $arraykey; // function returns by value!
}

$array = array('a', 'b', 'c');
foreach (array_keys($array) as $key) {
    $y = &func($array[$key]);
    $z[] =& $y;
}

var_dump($z);
?>
<]]>
    </programlisting>
    <para>
     Running the above script under any version of PHP that pre-dates the
     reference fix would produce this output:
    </para>
    <screen>
<![CDATA[
array(3) {
  [0]=>
  &string(1) "a"
  [1]=>
  &string(1) "b"
  [2]=>
  &string(1) "c"
}
]]>
    </screen>
    <para>
     Following the reference fix, the same code would result in:
    </para>
    <screen>
<![CDATA[
array(3) {
  [0]=>
  &string(1) "c"
  [1]=>
  &string(1) "c"
  [2]=>
  &string(1) "c"
}
]]>
    </screen>
   </informalexample>
   <para>
    This is because, following the changes, <literal>func()</literal>
    assigns by value. The value of <varname>$y</varname> is re-assigned,
    and reference-binding is preserved from <varname>$z</varname>. Prior to
    the fix, the value was assigned by reference, leading <varname>$y</varname>
    to be re-bound on each assignment. The attempt to bind to a temporary
    value by reference was the cause of the memory corruption.
   </para>
   <para>
    Such code can be made to work identically in both the pre-fix and the
    post-fix PHP versions. The signature of <literal>func()</literal> can
    be altered to return by reference, or the reference assignment can be
    removed from the result of <literal>func()</literal>.
   </para>
   <informalexample>
    <programlisting role="php">
<![CDATA[
<?php
function func() {
    return 'function return';
}

$x = 'original value';
$y =& $x;
$y = &func();
echo $x;
?>
]]>
    </programlisting>
   </informalexample>
   <para>
    In PHP 4.3 <varname>$x</varname> would be 'original value', whereas after
    the changes it would be 'function return' - remember that where the
    function does not return by reference, the reference assignment is
    converted to a regular assignment. Again, this can be brought to a common
    base, either by forcing <literal>func()</literal> to return by reference
    or by eliminating the by-reference assignment.
   </para>
  </section>

  <section xml:id="migration51.references-error">
   <title>Code that worked under PHP 4.3.x, but now throws an error</title>
   <informalexample>
    <programlisting role="php">
<![CDATA[
<?php
class Foo {

    function getThis() {
        return $this;
    }

    function destroyThis() {
        $baz =& $this->getThis();
    }
}

$bar = new Foo();
$bar->destroyThis();
var_dump($bar);
?>
]]>
    </programlisting>
   </informalexample>
   <para>
    In PHP 5.0.3, <varname>$bar</varname> evaluated to <constant>NULL</constant>
    instead of returning an object. That happened because
    <literal>getThis()</literal> returns by value, but the value here is
    assigned by reference. Although it now works in the expected way, this is
    actually invalid code which will throw an <constant>E_NOTICE</constant>
    under PHP 4.4 or an <constant>E_STRICT</constant> under PHP 5.0.4 and up.
   </para>
  </section>

  <section xml:id="migration51.references-works">
   <title>Code that failed under PHP 4.3.x, but now works</title>
   <informalexample>
    <programlisting role="php">
<![CDATA[
<?php
function &f() {
    $x = "foo";
    var_dump($x);
    print "$x\n";
    return($a);
}

for ($i = 0; $i < 3; $i++) {
    $h = &f();
}
?>
]]>
    </programlisting>
    <para>
     In PHP 4.3 the third call to <function>var_dump</function> produces
     <constant>NULL</constant>, due to the memory corruption caused by
     returning an uninitialized value by reference. This is valid code
     in PHP 5.0.4 and up, but threw errors in earlier releases of PHP.
    </para>
   </informalexample>
   <informalexample>
    <programlisting role="php">
<![CDATA[
<?php
$arr = array('a1' => array('alfa' => 'ok'));
$arr =& $arr['a1'];
echo '-'.$arr['alfa']."-\n";
?>
]]>
    </programlisting>
    <para>
     Until PHP 5.0.5, it wasn't possible to assign an array element by
     reference in this way. It now is.
    </para>
   </informalexample>
  </section>

  <section xml:id="migration51.references-didnotwork">
   <title>Code that <literal>should have worked</literal> under PHP 5.0.x</title>
   <para>
    There are a couple of instances of bugs reported under PHP 5.0 prior to
    the reference fixes which now 'work'. However, in both cases errors are
    thrown by PHP 5.1.x, because the code was invalid in the first place.
    Returning values by reference using <literal>self::</literal> now works
    in the general case but throws an <constant>E_STRICT</constant> warning,
    and although your mileage may vary when assigning by reference to an
    overloaded object, you will still see an <constant>E_ERROR</constant>
    when you try it, even where the assignment itself appears to work.
   </para>
  </section>

  <section xml:id="migration51.references-warnings">
   <title>Warnings that came and went</title>
   <para>
    Nested calls to functions returning by reference are valid code under both
    PHP 4.3.x and PHP 5.1.x, but threw an unwarranted
    <constant>E_NOTICE</constant> or <constant>E_STRICT</constant> under the
    intervening PHP releases.
   </para>
   <informalexample>
    <programlisting role="php">
<![CDATA[
<?php
function & foo() {
    $var = 'ok';
    return $var;
}

function & bar() {
    return foo();
}

$a =& bar();
echo "$a\n";
?>
]]>
    </programlisting>
   </informalexample>
  </section>
 </section>
 <section xml:id="migration51.reading">
  <title>Reading []</title>
  <informalexample>
   <programlisting role="php">
<![CDATA[
<?php
class XmlTest {

    function test_ref(&$test) {
        $test = "ok";
    }

    function test($test) { }

    function run() {
        $ar = array();
        $this->test_ref($ar[]);
        var_dump($ar);
        $this->test($ar[]);
    }
}

$o = new XmlTest();
$o->run();
?>
]]>
   </programlisting>
  </informalexample>
  <para>
   This should always have thrown a fatal <constant>E_ERROR</constant>,
   because [] cannot be used for reading in PHP. It is invalid code in
   PHP 4.4.2 and PHP 5.0.5 upward.
  </para>
 </section>

 <section xml:id="migration51.integer-parameters">
  <title>Integer values in function parameters</title>
  <para>
   With the advent of PHP 5.0.x, a new parameter parsing API was introduced
   which is used by a large number of PHP functions. In all versions of PHP
   between 5.0.x and 5.1.x, the handling of integer values was very strict and
   would reject non-well formed numeric values when a PHP function expected an
   integer. These checks have now been relaxed to support non-well formed
   numeric strings such as " 123" and "123 ", and will no longer fail as they
   did under PHP 5.0.x. However, to promote code safety and input validation,
   PHP functions will now emit an <constant>E_NOTICE</constant> when such
   strings are passed as integers.
  </para>
 </section>

 <section xml:id="migration51.oop">
  <title>Class and object changes</title>
  <itemizedlist>
   <listitem>
    <para>
     <link linkend="migration51.oop-functions"><literal>instanceof</literal>,
      <literal>is_a()</literal>, <literal>is_subclass_of()</literal> and
      <literal>catch</literal></link>
    </para>
   </listitem>
   <listitem>
    <para>
     <link linkend="migration51.oop-methods">Abstract private methods</link>
    </para>
   </listitem>
   <listitem>
    <para>
     <link linkend="migration51.oop-modifiers">Access modifiers in
      interfaces</link>
    </para>
   </listitem>
   <listitem>
    <para>
     <link linkend="migration51.oop-inheritance">Changes in inheritance
      rules</link>
    </para>
   </listitem>
   <listitem>
    <para>
     <link linkend="migration51.oop-constants">Class constants</link>
    </para>
   </listitem>
  </itemizedlist>

  <section xml:id="migration51.oop-functions">
   <title><literal>instanceof</literal>, <literal>is_a()</literal>,
    <literal>is_subclass_of()</literal> and <literal>catch</literal></title>
   <para>
    In PHP 5.0, <literal>is_a()</literal> was deprecated and replaced by the
    <literal>instanceof</literal> operator. There were some issues with the
    initial implementation of <literal>instanceof</literal>, which relied on
    <literal>__autoload()</literal> to search for missing classes.
    If the class was not present, <literal>instanceof</literal> would throw
    a fatal <constant>E_ERROR</constant> due to the failure of
    <literal>__autoload()</literal> to discover that class. The same behaviour
    occurred in the <literal>catch</literal> operator and the
    <literal>is_subclass_of()</literal> function, for the same reason.
   </para>
   <para>
    None of these functions or operators call <literal>__autoload()</literal>
    in PHP 5.1.x, and the <literal>class_exists()</literal> workarounds used
    in code written for PHP 5.0.x, while not problematic in any way, are no
    longer necessary.
   </para>
  </section>

  <section xml:id="migration51.oop-methods">
   <title>Abstract private methods</title>
   <para>
    Abstract private methods were supported between PHP 5.0.0 and PHP 5.0.4,
    but were then disallowed on the grounds that the behaviours of
    <literal>private</literal> and <literal>abstract</literal> are mutually
    exclusive.
   </para>
  </section>

  <section xml:id="migration51.oop-modifiers">
   <title>Access modifiers in interfaces</title>
   <para>
    Under PHP 5.0, function declarations in interfaces were treated in exactly
    the same way as function declarations in classes. This has not been the
    case since October 2004, at which point only the <literal>public</literal>
    access modifier was allowed in interface function declarations. Since
    April 2005 - which pre-dates the PHP 5.0b1 release - the
    <literal>static</literal> modifier has also been allowed. However, the
    <literal>protected</literal> and <literal>private</literal> modifiers will
    now throw an <constant>E_ERROR</constant>, as will
    <literal>abstract</literal>. Note that this change should not affect your
    existing code, as none of these modifiers makes sense in the context of
    interfaces anyway.
   </para>
  </section>

  <section xml:id="migration51.oop-inheritance">
   <title>Changes in inheritance rules</title>
   <para>
    Under PHP 5.0, it was possible to have a function declaration in a derived
    class that did not match the declaration of the same function in the base
    class, e.g.
   </para>
   <informalexample>
    <para>
     This code will cause an <constant>E_STRICT</constant> error to be emitted
     under PHP 5.1.x.
    </para>
    <programlisting role="php">
<![CDATA[
<?php
class Base {
    function &return_by_ref() {
        $r = 1;
        return $r;
    }
}

class Derived extends Base {
    function return_by_ref() {
        return 1;
    }
}
?>
]]>
    </programlisting>
   </informalexample>
  </section>

  <section xml:id="migration51.oop-constants">
   <title>Class constants</title>
   <para>
    Under PHP 5.0.x, the following code was valid:
   </para>
   <informalexample>
    <para>
     Under PHP 5.1.x, redefinition of a class constant will throw a fatal
     <constant>E_ERROR</constant>.
    </para>
    <programlisting role="php">
<![CDATA[
<?php
class test {
    const foobar = 'foo';
    const foobar = 'bar';
}

?>
]]>
    </programlisting>
   </informalexample>
  </section>
 </section> 

 <section xml:id="migration51.extensions">
  <title>Extensions</title>
  <itemizedlist>
   <listitem>
    <para>
     <link linkend="migration51.extensions-gone">Extensions that are gone
      from the PHP core</link>
    </para>
   </listitem>
   <listitem>
    <para>
     <link linkend="migration51.extensions-constants">Class constants in new
      PHP 5.1.x extensions</link>
    </para>
   </listitem>
  </itemizedlist>

  <section xml:id="migration51.extensions-gone">
   <title>Extensions that are gone from the PHP core</title>
   <para>
    One of the first things you're likely to notice when you download PHP 5.1.x
    is that several of the older extensions have disappeared. Those extensions
    that are still actively maintained are available in the PHP Extension
    Community Library (PECL), at
    <link xlink:href="&url.pecl;">&url.pecl;</link>.
   </para>
   <table>
    <title>Removed extensions</title>
    <tgroup cols="2">
     <thead>
      <row>
       <entry>Extension</entry>
       <entry>Alternative/Status</entry>
      </row>
     </thead>
     <tbody>
      <row>
       <entry>ext/cpdf</entry>
       <entry><link linkend="ref.pdf">pecl/pdflib</link></entry>
      </row>
      <row>
       <entry><link linkend="ref.dbx">ext/dbx</link></entry>
       <entry>pecl/dbx</entry>
      </row>
      <row>
       <entry><link linkend="ref.dio">ext/dio</link></entry>
       <entry>pecl/dio</entry>
      </row>
      <row>
       <entry><link linkend="ref.fam">ext/fam</link></entry>
       <entry>Not actively maintained</entry>
      </row>
      <row>
       <entry><link linkend="ref.ingres">ext/ingres_ii</link></entry>
       <entry>pecl/ingres</entry>
      </row>
      <row>
       <entry>ext/ircg</entry>
       <entry>Not actively maintained</entry>
      </row>
      <row>
       <entry><link linkend="ref.mcve">ext/mcve</link></entry>
       <entry>pecl/mcve</entry>
      </row>
      <row>
       <entry><link linkend="ref.mnogosearch">ext/mnogosearch</link></entry>
       <entry>Not actively maintained</entry>
      </row>
      <row>
       <entry>ext/oracle</entry>
       <entry>
        <link linkend="ref.oci8">ext/oci8</link> or
        <link linkend="ref.pdo-oci">ext/pdo_oci</link>
       </entry>
      </row>
      <row>
       <entry><link linkend="ref.ovrimos">ext/ovrimos</link></entry>
       <entry>Not actively maintained</entry>
      </row>
      <row>
       <entry>ext/pfpro</entry>
       <entry>Not actively maintained</entry>
      </row>
      <row>
       <entry><link linkend="ref.w32api">ext/w32api</link></entry>
       <entry><link xlink:href="&url.pecl.package;ffi">pecl/ffi</link></entry>
      </row>
      <row>
       <entry><link linkend="ref.nis">ext/yp</link></entry>
       <entry>Not actively maintained</entry>
      </row>
      <row>
       <entry>ext/activescript</entry>
       <entry>
        <link xlink:href="&url.pecl.package;activescript">pecl/activescript</link>
       </entry>
      </row>
     </tbody>
    </tgroup>
   </table>
   <para>
    Modules in PECL that are not actively maintained (i.e. have not been
    supported for some time, have no active maintainer working on them
    currently, and do not have any PECL package releases), are still available
    in SVN at <link xlink:href="&url.php.svn;pecl">&url.php.svn;pecl</link>.
    However, unreleased PHP modules are by their nature unsupported, and your
    mileage may vary when attempting to install or use them.
   </para>
  </section>

  <section xml:id="migration51.extensions-constants">
   <title>Class constants in new PHP 5.1.x extensions</title>
   <para>
    The Zend Engine 2.1 API allows extension developers to declare class
    constants in object oriented extensions. New extensions written for PHP
    5.1.x, including <link linkend="ref.spl">SPL</link>,
    <link linkend="intro.pdo">PDO</link>,
    <link linkend="book.xmlreader">XMLReader</link> and
    <link linkend="ref.datetime">date</link>, have their constants in
    the format <constant>PDO::CLASS_CONSTANT</constant> rather than in the C
    format <constant>PDO_CLASS_CONSTANT</constant> in order to minimise
    pollution of the global namespace in PHP.
   </para>
  </section>
 </section>

 <section xml:id="migration51.datetime">
  <title>Date/time support</title>
  <para>
   Date/time support has been fully rewritten in PHP 5.1.x, and no longer uses
   the system settings to 'know' the timezone in operation. It will instead
   utilize, in the following order:
  </para>
  <itemizedlist>
   <listitem>
    <para>
     The timezone set using the <function>date_default_timezone_set</function>
     function (if any)
    </para>
   </listitem>
   <listitem>
    <para>
     The TZ environment variable (if non empty)
    </para>
   </listitem>
   <listitem>
    <para>
     "magical" guess (if the operating system supports it)
    </para>
   </listitem>
   <listitem>
    <para>
     If none of the above options succeeds, UTC
    </para>
   </listitem>
  </itemizedlist>
  <informalexample>
   <para>
    To ensure accuracy (and avoid an <constant>E_STRICT</constant> warning),
    you will need to define your timezone in your <filename>php.ini</filename>
    using the following format:
   </para>
   <para>
    date.timezone = Europe/London
   </para>
  </informalexample>
  <para>
   The supported timezones are listed, in this format, in the
   <link linkend="timezones">timezones appendix</link>.
  </para>
  <para>
   Also note that <function>strtotime</function> now returns &false; on
   failure, instead of -1. 
  </para>
 </section>

 <section xml:id="migration51.databases">
  <title>Changes in database support</title>
  <itemizedlist>
   <listitem>
    <para>
     <link linkend="migration51.databases-pdo">PDO overview</link>
    </para>
   </listitem>
   <listitem>
    <para>
     <link linkend="migration51.databases-mysql">Changes in MySQL support</link>
    </para>
   </listitem>
   <listitem>
    <para>
     <link linkend="migration51.databases-sqlite">Changes in SQLite support</link>
    </para>
   </listitem>
  </itemizedlist>

  <section xml:id="migration51.databases-pdo">
   <title>PDO overview</title>
   <para>
    <link linkend="intro.pdo">PHP Data Objects (PDO)</link> were introduced as a
    PECL extension under PHP 5.0, and became part of the core PHP distribution
    in PHP 5.1.x. The PDO extension provides a consistent interface for database
    access, and is used alongside database-specific PDO drivers. Each driver
    may also have database-specific functions of its own, but basic data
    access functionality such as issuing queries and fetching data is covered
    by PDO functions, using the driver named in
    <function>PDO::__construct</function>.
   </para>
   <para>
    Note that the PDO extension, and its drivers, are intended to be built as
    shared extensions. This will enable straightforward driver upgrades from
    PECL, without forcing you to rebuild all of PHP.
   </para>
   <para>
    At the point of the PHP 5.1.x release, PDO is more than ready for widespread
    testing and could be adopted in most situations. However, it is important
    to understand that PDO and its drivers are comparatively young and may be
    missing certain database-specific features; evaluate PDO carefully before
    you use it in new projects.
   </para>
   <para>
    Legacy code will generally rely on the pre-existing database extensions,
    which are still maintained.
   </para>
  </section>

  <section xml:id="migration51.databases-mysql">
   <title>Changes in MySQL support</title>
   <para>
    In PHP 4, MySQL 3 support was built-in. With the release of PHP 5.0 there
    were two MySQL extensions, named 'mysql' and 'mysqli', which were designed
    to support MySQL &lt; 4.1 and MySQL 4.1 and up, respectively. With the
    introduction of PDO, which provides a very fast interface to all the
    database APIs supported by PHP, the PDO_MYSQL driver can support any of
    the current versions (MySQL 3, 4 or 5) in PHP code written for PDO,
    depending on the MySQL library version used during compilation. The older
    MySQL extensions remain in place for reasons of back compatibility, but
    are not enabled by default.
   </para>
  </section>

  <section xml:id="migration51.databases-sqlite">
   <title>Changes in SQLite support</title>
   <para>
    In PHP 5.0.x, SQLite 2 support was provided by the built-in sqlite
    extension, which was also available as a PECL extension in PHP 4.3 and PHP
    4.4. With the introduction of PDO, the sqlite extension doubles up to act
    as a 'sqlite2' driver for PDO; it is due to this that the sqlite extension
    in PHP 5.1.x has a dependency upon the PDO extension.
   </para>
   <para>
    PHP 5.1.x ships with a number of alternative interfaces to sqlite:
   </para>
   <para>
    The sqlite extension provides the "classic" sqlite procedural/OO API that
    you may have used in prior versions of PHP. It also provides the PDO
    'sqlite2' driver, which allows you to access legacy SQLite 2 databases
    using the PDO API.
   </para>
   <para>
    PDO_SQLITE provides the 'sqlite' version 3 driver. SQLite version 3 is
    vastly superior to SQLite version 2, but the file formats of the two
    versions are not compatible.
   </para>
   <para>
    If your SQLite-based project is already written and working against
    earlier PHP versions, then you can continue to use ext/sqlite without
    problems, but will need to explicitly enable both PDO and sqlite. New
    projects should use PDO and the 'sqlite' (version 3) driver, as this is
    faster than SQLite 2, has improved locking concurrency, and supports both
    prepared statements and binary columns natively.
   </para>
   <para>
    You must enable PDO to use the SQLite extension. If you want to build the
    PDO extension as a shared extension, then the SQLite extension must also
    be built shared. The same holds true for any extension that provides a PDO
    driver 
   </para>
  </section>
 </section> <!-- end of migration51.databases -->

 <section xml:id="migration51.errorcheck">
  <title>Checking for <constant>E_STRICT</constant></title>
  <informalexample>
   <para>
    If you only have a single script to check, you can pick up
    <constant>E_STRICT</constant> errors using PHP's commandline lint
    facility:
   </para>
   <programlisting role="shell">
    php -d error_reporting=4095 -l script_to_check.php
   </programlisting>
   <para>
    For larger projects, the shell script below will achieve the same task:
   </para>
   <programlisting role="shell">
<![CDATA[
#!/bin/sh

directory=$1

shift

# These extensions are checked
extensions="php inc"

check_file ()
{
  echo -ne "Doing PHP syntax check on $1 ..."

  # Options:
  ERRORS=`/www/php/bin/php -d display_errors=1 -d html_errors=0 -d error_prepend_string=" " -d error_append_string=" " -d error_reporting=4095 -l $1 | grep -v "No syntax errors detected"`

  if test -z "$ERRORS"; then
    echo -ne "OK."
  else
    echo -e "Errors found!\n$ERRORS"
  fi

  echo
}

# loop over remaining file args
for FILE in "$@" ; do
  for ext in $extensions; do
     if echo $FILE | grep "\.$ext$" > /dev/null; then
       if test -f $FILE; then
         check_file "$FILE"
       fi
     fi
  done
done
]]>
   </programlisting>
  </informalexample>
 </section>

</appendix>

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