PHP: Documentation Tools

chapters/tutorial.xml
46ffb4b3fa11ea5733de780a8bcc211d8dc3d92b

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@@ -69,13 +69,14 @@

     <info><title>Our first PHP script: <filename>hello.php</filename></title></info>

     <programlisting role="php">

<![CDATA[

<!DOCTYPE html>

<html>

 <head>

  <title>PHP Test</title>

 </head>

 <body>

 <?php echo '<p>Hello World</p>'; ?> 

 </body>

    <head>

        <title>PHP Test</title>

    </head>

    <body>

        <?php echo '<p>Hello World</p>'; ?>

    </body>

</html>

]]>

     </programlisting>

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@@ -90,13 +91,14 @@

     </simpara>

     <screen role="html">

<![CDATA[

<!DOCTYPE html>

<html>

 <head>

  <title>PHP Test</title>

 </head>

 <body>

 <p>Hello World</p>

 </body>

    <head>

        <title>PHP Test</title>

    </head>

    <body>

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        <p>Hello World</p>

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    </body>

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</html>

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]]>

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     </screen>

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@@ -174,20 +176,6 @@

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    </para>

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   </note>

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   <note>

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    <info><title>A Note on Windows Notepad</title></info>

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    <para>

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     If you are writing your PHP scripts using Windows Notepad, you will need

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     to ensure that your files are saved with the <filename>.php</filename> extension.

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     (Notepad adds a <filename>.txt</filename> extension to files automatically unless

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     you take one of the following steps to prevent it.)  When you save the file and

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     are prompted to provide a name for the file, place the filename in quotes 

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     (i.e. "<filename>hello.php</filename>").  Alternatively, you can click on the 

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     'Text Documents' drop-down menu in the 'Save' dialog box and change the setting 

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     to "All Files". You can then enter your filename without quotes.

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    </para>

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   </note>

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   <para>

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    Now that you have successfully created a working PHP script, it is

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    time to create the most famous PHP script!  Make a call to the

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     special reserved PHP variable that contains all web server information.

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     It is known as a superglobal.  See the related manual page on

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     <link linkend="language.variables.superglobals">superglobals</link>

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     for more information.  These special variables were introduced in PHP 

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     <link xlink:href="&url.php.release4.1.0;">4.1.0</link>.  Before this time, we used

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     the older <varname>$HTTP_*_VARS</varname> arrays instead,

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     such as <varname>$HTTP_SERVER_VARS</varname>.  As of PHP 5.4.0 

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     these older variables have been removed.  (See also the note on

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     <link linkend="tutorial.oldcode">old code</link>.)

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     for more information.

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    </para>

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   </note>

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   <para>

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     A sample output of this script may be:

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    </para>

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    <screen role="html">

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Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)

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<![CDATA[

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Mozilla/5.0 (Linux) Firefox/112.0

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]]>

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    </screen>

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   </example>

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   </para>

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   <para>

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    There are many <link linkend="language.types">types</link> of 

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    variables available in PHP.  In the above example we printed 

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    an <link linkend="language.types.array">Array</link> element.

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    variables available in PHP.  In the above example we printed an element

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    from an <link linkend="language.types.array">Array</link> variable.

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    Arrays can be very useful.

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   </para>

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   <para>

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@@ -272,7 +257,7 @@ Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)

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   <para>

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    You can put multiple PHP statements inside a PHP tag and create

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    little blocks of code that do more than just a single echo.

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    For example, if you want to check for Internet Explorer you

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    For example, if you want to check for Firefox you

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    can do this:

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   </para>

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   <para>

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@@ -282,8 +267,8 @@ Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)

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     <programlisting role="php">

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<![CDATA[

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<?php

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if (strpos($_SERVER['HTTP_USER_AGENT'], 'MSIE') !== FALSE) {

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    echo 'You are using Internet Explorer.<br />';

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if (str_contains($_SERVER['HTTP_USER_AGENT'], 'Firefox')) {

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    echo 'You are using Firefox.';

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}

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?>

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]]>

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     </para>

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     <screen role="html">

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<![CDATA[

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You are using Internet Explorer.<br />

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You are using Firefox.

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]]>

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     </screen>

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    </example>

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@@ -308,14 +293,13 @@ You are using Internet Explorer.<br />

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    Reference</link> part of the manual.

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   </para>

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   <para>

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    The second concept we introduced was the <function>strpos</function>

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    function call. <function>strpos</function> is a function built into

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    PHP which searches a string for another string. In this case we are

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    looking for <literal>'MSIE'</literal> (so-called needle) inside

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    The second concept we introduced was the <function>str_contains</function>

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    function call. <function>str_contains</function> is a function built into

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    PHP which determines if a given string contains another string. In this case we are

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    looking for <literal>'Firefox'</literal> (so-called needle) inside

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    <varname>$_SERVER['HTTP_USER_AGENT']</varname> (so-called haystack).  If

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    the needle is found inside the haystack, the function returns the position

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    of the needle relative to the start of the haystack.  Otherwise, it

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    returns &false;.  If it does not return &false;, the <link

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    the needle is found inside the haystack, the function returns true. Otherwise, it

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    returns &false;. If it returns &true;, the <link

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    linkend="control-structures.if">if</link> expression evaluates to &true;

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    and the code within its {braces} is executed. Otherwise, the code is not

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    run. Feel free to create similar examples, 

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     <programlisting role="php">

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<![CDATA[

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<?php

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if (strpos($_SERVER['HTTP_USER_AGENT'], 'MSIE') !== FALSE) {

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if (str_contains($_SERVER['HTTP_USER_AGENT'], 'Firefox')) {

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?>

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<h3>strpos() must have returned non-false</h3>

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<p>You are using Internet Explorer</p>

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<h3>str_contains() returned true</h3>

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<p>You are using Firefox</p>

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<?php

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} else {

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?>

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<h3>strpos() must have returned false</h3>

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<p>You are not using Internet Explorer</p>

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<h3>str_contains() returned false</h3>

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<p>You are not using Firefox</p>

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<?php

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}

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?>

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     </para>

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     <screen role="html">

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<![CDATA[

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<h3>strpos() must have returned non-false</h3>

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<p>You are using Internet Explorer</p>

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<h3>str_contains() returned true</h3>

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<p>You are using Firefox</p>

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]]>

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     </screen>

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    </example>

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    of PHP mode and just sent straight HTML. The important and powerful point

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    to note here is that the logical flow of the script remains intact. Only

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    one of the HTML blocks will end up getting sent to the viewer depending on

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    the result of <function>strpos</function>.  In other words, it depends on

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    whether the string <literal>MSIE</literal> was found or not.

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    the result of <function>str_contains</function>.  In other words, it depends on

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    whether the string <literal>Firefox</literal> was found or not.

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   </para>

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  </section>

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     <programlisting role="html">

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<![CDATA[

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<form action="action.php" method="post">

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 <p>Your name: <input type="text" name="name" /></p>

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 <p>Your age: <input type="text" name="age" /></p>

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 <p><input type="submit" /></p>

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    <label for="name">Your name:</label>

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    <input name="name" id="name" type="text">

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    <label for="age">Your age:</label>

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    <input name="age" id="age" type="number">

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    <button type="submit">Submit</button>

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</form>

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]]>

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     </programlisting>

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   </para>

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  </section>

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  <section xml:id="tutorial.oldcode">

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   <info><title>Using old code with new versions of PHP</title></info>

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   <para>

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    Now that PHP has grown to be a popular scripting language, there are

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    a lot of public repositories and libraries containing code you can reuse.

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    The PHP developers have largely tried to preserve backwards compatibility, 

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    so a script written for an older version will run (ideally) without changes

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    in a newer version of PHP. In practice, some changes will usually be needed.

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   </para>

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   <para>

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    Two of the most important recent changes that affect old code are:

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    <itemizedlist>

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     <listitem>

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      <simpara>

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       The old <varname>$HTTP_*_VARS</varname> arrays are not available as of 

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       PHP 5.4.0. The following 

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       <link linkend="language.variables.superglobals">superglobal arrays</link>

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       were introduced in PHP <link xlink:href="&url.php.release4.1.0;">4.1.0</link>. 

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       They are: <varname>$_GET</varname>, <varname>$_POST</varname>, 

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       <varname>$_COOKIE</varname>, <varname>$_SERVER</varname>, 

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       <varname>$_FILES</varname>, <varname>$_ENV</varname>,

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       <varname>$_REQUEST</varname>, and <varname>$_SESSION</varname>.  

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      </simpara>

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     </listitem>

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     <listitem>

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      <simpara>

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       External variables are no longer registered in the global scope by

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       default.  In other words, as of PHP

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       <link xlink:href="&url.php.release4.2.0;">4.2.0</link> the PHP directive 

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       <literal>register_globals</literal> is 

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       <emphasis>off</emphasis> by default in &php.ini;. The preferred 

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       method of accessing these values is via the superglobal arrays mentioned

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       above.  Older scripts, books, and tutorials may rely on this 

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       directive being <literal>on</literal>.  If it were <literal>on</literal>,

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       for example, one could use  <varname>$id</varname> from the URL 

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       <literal>http://www.example.com/foo.php?id=42</literal>.  Whether on 

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       or off, <varname>$_GET['id']</varname> is available.

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      </simpara>

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     </listitem>

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    </itemizedlist>

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    For more details on these changes, see the section on 

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    <link linkend="language.variables.predefined">predefined variables</link>

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    and links therein.

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   </para>

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  </section>

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  <section xml:id="tutorial.whatsnext">

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   <info><title>What's next?</title></info>

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   <para>

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