chapters/tutorial.xml
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<info><title>What do I need?</title></info>
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<para>
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In this tutorial we assume that your server has activated support
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for PHP and that all files ending in <filename>.php</filename>
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for PHP and that all files ending in <filename class="extension">.php</filename>
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are handled by PHP. On most servers, this is the default extension
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for PHP files, but ask your server administrator to be sure. If
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your server supports PHP, then you do not need to do anything. Just
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create your <filename>.php</filename> files, put them in your
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create your <filename class="extension">.php</filename> files, put them in your
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web directory and the server will automatically parse them for you.
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There is no need to compile anything nor do you need to install
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any extra tools. Think of these PHP-enabled files as simple HTML
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<info><title>Our first PHP script: <filename>hello.php</filename></title></info>
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<programlisting role="php">
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<![CDATA[
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<html>
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<head>
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<title>PHP Test</title>
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</head>
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<body>
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<?php echo '<p>Hello World</p>'; ?>
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</body>
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</html>
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<?php
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echo "Hello World!";
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?>
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]]>
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</programlisting>
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<simpara>
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URL will be something like <literal>http://localhost/hello.php</literal>
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or <literal>http://127.0.0.1/hello.php</literal> but this depends on the
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web server's configuration. If everything is configured correctly, this
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file will be parsed by PHP and the following output will be sent to
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your browser:
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file will be parsed by PHP and you will see the "Hello World" output displayed
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in your browser.
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</simpara>
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<simpara>
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PHP can be embedded within a normal HTML web page. That means inside your HTML document
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you can write the PHP statements, as demonstrated in the following example:
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</simpara>
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<programlisting role="php">
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<![CDATA[
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<!DOCTYPE html>
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<html>
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<head>
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<title>PHP Test</title>
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</head>
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<body>
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<?php echo '<p>Hello World</p>'; ?>
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</body>
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</html>
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]]>
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</programlisting>
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<simpara>
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This will result in the following output:
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</simpara>
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<screen role="html">
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<![CDATA[
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<!DOCTYPE html>
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<html>
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<head>
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<title>PHP Test</title>
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</head>
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<body>
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<p>Hello World</p>
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</body>
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<head>
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<title>PHP Test</title>
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</head>
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<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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</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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<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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<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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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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<programlisting role="php">
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<![CDATA[
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Hi <?php echo htmlspecialchars($_POST['name']); ?>.
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You are <?php echo (int)$_POST['age']; ?> years old.
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You are <?php echo (int) $_POST['age']; ?> years old.
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]]>
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</programlisting>
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<para>
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superglobal, if you do not care about the source of your request data. It
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contains the merged information of GET, POST and COOKIE data.
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</para>
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<para>
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You can also deal with XForms input in PHP, although you will find yourself
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comfortable with the well supported HTML forms for quite some time.
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While working with XForms is not for beginners, you might be interested
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in them. We also have a <link linkend="features.xforms">short introduction
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to handling data received from XForms</link> in our features section.
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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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Translation status