An Introduction to PHP

Getting Started

PHP scripts have the extension .php. The PHP script is placed between the <?php and ?> delimiters. The script that is placed between these delimiters is interpreted on the server into HMTL, before being sent to the client. The client will receive a pure HTML page.

Comments

You can comment your code using C++ type comments. The following shows the syntax for inline comments (a comment on a single line), and block comments (comments placed over several lines).

// This is an inline comment
/*
This is a block comment
placed over two or more
lines
*/

Output

There are two basic statements to output text with PHP, either using echo, or print.

Output Using echo

The text to be outputed follows the echo statement.

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
  <title>Starting PHP</title>
  <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
</head>
<body>
<p>
  <?php echo "Hello World<br>"; ?>
</p>
</body>
</html>

Output using print

The text to be outputed follows the print statement.

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
  <title>Starting PHP</title>
  <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
</head>
<body>
<p>
  <?php print "Hello World<br>"; ?>
</p>
</body>
</html>

PHP also offers a shothand way of outputting information, using the <?= and ?> delimiters. The following example prints the variable $name (passed from a form) to greet a user.

Hello <?=$name?>

PHP Information

The phpinfo function is useful for trouble shooting, providing the version of PHP, and how it is configured.

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
  <title>PHP Information</title>
  <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
</head>
<body>
<p>
  <?php phpinfo();?>
</p>
</body>
</html>

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Comments

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Gez Lemon United Kingdom

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