CMPF123 - Chapter 5

Chapter Overview

Title: PHP: Hypertext Preprocessor
Course: CMPF 123: Introduction to Web Development

Learning Outcomes

At the end of this lesson, students should be able to:
- Understand basic PHP concepts
- Perform basic operations using PHP
- Apply PHP codes in HTML pages where appropriate

Topics Covered

Introduction to PHP
Strings
Installation of PHP
Constants
Syntax
Operators
Variables
Conditional Statements
Echo/Print
Loops
Data Types

PHP Basics

What is PHP?

Definition: PHP stands for "PHP: Hypertext Preprocessor".
Type: PHP is a server scripting language and a powerful tool for creating dynamic and interactive web pages.
Comparison: It is a widely-used, free, efficient alternative to Microsoft ASP.

Understanding PHP Files

Knowledge Requirement: Students should have a basic understanding of HTML, CSS, and JavaScript.
Content: PHP files can contain text, HTML, CSS, JavaScript, and PHP code.
Execution: PHP code is executed on the web server, and results are returned as plain HTML.
File Extension: PHP files have the extension ".php".

PHP Functionalities

Can:
- Generate dynamic page content
- Handle files on the server (create, open, read, write, delete)
- Collect form data
- Manage cookies
- Manipulate database data
- Control user access
- Encrypt data

Requirements to Start with PHP

Option 1: Find a web host that supports PHP.
Option 2: Install a web server on your PC and then PHP.
- Example Tools:
  - WampServer: A web development platform for Windows.
  - XAMPP: Provides Apache server, MySQL, PHP, and Perl for multiple operating systems.

Creating and Executing PHP Programs

Initial Setup

Open a code editor.
Type the code:
```
<?php
phpinfo();
?>
```
Save the file as phpinfo.php in the web server’s root directory (e.g., wamp/www).

Test the Setup

In your web browser, navigate to: http://localhost/phpinfo.php. If successful, congratulations!

PHP Syntax

A PHP script is executed on the server, and the resulting HTML is sent back to the browser.
PHP scripts begin with <?php and end with ?>.

Basic PHP Program Example

<!DOCTYPE html>
<html>
<body>
<h1>My first PHP page</h1>
<?php echo "Testing 123"; ?>
</body>
</html>

PHP Comments

Used to:
- Explain code to others.
- Remind oneself of code functionality.

Case Sensitivity in PHP

Keywords (if, else, while, echo, etc.), classes, functions, and user-defined functions are not case-sensitive.
Variable names are case-sensitive.

PHP Variables

Variables start with a $ sign.

Examples:

<?php
$txt = "Hello world!";
$x = 5;
 $y = 10.5;</code></pre></li><li class="drag"><p><strong>Rules</strong>:</p><ul><li class="drag"><p>Must start with a letter or underscore.</p></li><li class="drag"><p>Cannot start with a number.</p></li><li class="drag"><p>Can contain alphanumeric characters and underscores.</p></li><li class="drag"><p>Are case-sensitive.</p></li></ul></li></ul><h3><span class="heading-content">Echo/Print Statements</span></h3><ul><li class="drag"><p><strong>Echo</strong>: A statement used to output data.</p></li><li class="drag"><p>Example usage:</p></li></ul><pre><code class="language-php"><?php echo "Hello, World!"; ?></code></pre><ul><li class="drag"><p>Outputting variables and results from operations can also be done using echo.</p></li></ul><h3><span class="heading-content">Data Types in PHP</span></h3><ul><li class="drag"><p><strong>Supported Types</strong>:</p><ul><li class="drag"><p><strong>String</strong>: Any text within quotes.</p></li><li class="drag"><p><strong>Integer</strong>: Non-decimal numbers in specified range.</p></li><li class="drag"><p><strong>Float</strong>: Numbers with decimals or exponential form.</p></li><li class="drag"><p><strong>Boolean</strong>: Represents true or false values.</p></li><li class="drag"><p><strong>Array</strong>: Stores multiple values in one variable.</p></li><li class="drag"><p><strong>Object</strong>: Instances of classes.</p></li><li class="drag"><p><strong>NULL</strong>: Represents a variable with no value.</p></li><li class="drag"><p><strong>Resource</strong>: Reference to external resources.</p></li></ul></li></ul><h3><span class="heading-content">PHP Arrays</span></h3><ul><li class="drag"><p><strong>Definition</strong>: An array can store multiple values.</p></li><li class="drag"><p><strong>Example</strong>:</p></li></ul><pre><code class="language-php">$ cars = array("Volvo", "BMW", "Toyota");

PHP Constants

Define constant values that cannot change: define(name, value, case-insensitive).

PHP Operators

Arithmetic Operators

Operator	Description	Example	Result
+	Addition	$x + $y	Sum of $x and $y
-	Subtraction	$x - $y	Difference of $x and $y
*	Multiplication	$x * $y	Product of $x and $y
/	Division	$x / $y	Quotient of $x and $y
%	Modulus	$x % $y	Remainder of $x / $y
**	Exponentiation	$x ** $y	$x raised to the power of $y

Comparison Operators

Operator	Description	Example	Result
==	Equal	$x == $y	True if $x equals $y
===	Identical	$x === $y	True if both value and type are equal
!=	Not Equal	$x != $y	True if $x is not equal to $y

Conditional Statements

Types

if: Executes code if a condition is true.
if...else: Executes different code based on conditions.
if...elseif...else: Handles multiple conditional checks.
switch: Selects from many blocks of code to be executed based on variable value.

PHP Loops

while: Executes block while condition is true.
do while: Executes at least once and continues while condition is true.
for: Loops for a specified number of iterations.
foreach: Loops through each element of an array.

Thank You!

Expressing gratitude in various languages.
- Example phrases included: "Gracias", "Arigato", "Merci", etc.