PHP Programming Notes

Introduction to PHP

• PHP stands for "PHP: Hypertext Preprocessor".
• Open source scripting language, widely-used, and freely available to download.
• Server required to execute PHP scripts.

PHP Overview

• Rasmus Lerdorf released the first version in 1994.
• Server-side scripting language embedded in HTML.
• Capable of managing dynamic content, databases, session tracking, and e-commerce applications.
• Integrates with popular databases like MySQL, PostgreSQL, and Oracle.
• Known for fast execution, especially as an Apache module on Unix.
• Supports protocols like POP3, IMAP, and LDAP.

Common Uses of PHP

• Perform system functions: Create, open, read, write, and close files.
• Handle forms: Collect data from users, save to files, and send data over email.
• Database manipulation: Add, delete, modify elements in databases, access cookies, and restrict user access to pages.

Installation of PHP and MySQL

Starting PHP

• Options to start PHP:
  • Find a web host with PHP and MySQL support.
  • Install a web server and database on PC.

Web Host with PHP Support

• Create .php files and store them in the web directory; the server parses them automatically.

Setting up PHP on Personal Computer

• If the server does not support PHP:
  • Install a web server and PHP.
  • Set up a database (e.g., MySQL).

Configuration Recommendations

• Check and configure IIS and PHP settings via the "php.ini" file.
• Use PHP Manager for IIS to set attributes for security.

Features of PHP

• Open Source: Free to use with no licensing fees.
• Extensive Library: Access to optimized code libraries for various tasks.
• Adaptable: Works with various platforms (Windows, Linux, etc.).
• Community Support: Large community for help and resources.
• Easy Maintenance: Framework assistance (like MVC) for managing code.

Advantages of PHP

• Scalable: Used for large projects (e.g., Facebook, WordPress).
• Free to Use: Popular for server-side scripting without cost.
• Ease of Use: Simple to learn due to forgiving syntax.
• Lightning Speed: Fast execution compared to other languages (e.g., three times faster than Python).

PHP Code Writing

Basic Syntax

• Use <?php to open and ?> to close PHP scripts.
• Default file extension for PHP files is ".php".
• Example for outputting text:

  <?php
echo "Hello World!";
?>

Executing PHP and Viewing in Browser

• PHP keywords and built-in functions are not case-sensitive (e.g., echo is the same as ECHO).
• Variables in PHP are case-sensitive.
  Example:

  <?php
  $color = "red";
echo "My car is " . $color . "!";
  ?>

Data Types in PHP

• Supported data types include:
  • String
  • Integer
  • Float
  • Boolean
  • Array
  • Object
  • NULL
  • Resource

PHP Strings

• A string is a sequence of characters.
• Can be created with single quotes ('') or double quotes ("").
• Example:

  $str = "Hello, World!";
  echo $str;

PHP Integers

• Integer ranges from -2,147,483,648 to 2,147,483,647.
• Can be decimal, hexadecimal, octal, or binary.

PHP Floats

• Float is a number with a decimal point.

Operators in PHP

• Arithmetic Operators: +, -, *, /, %
• Comparison Operators: ==, !=, ===, !==
• Logical Operators: and, or, &&, ||

Control Structures and Functions

Control Structures

• If statement: Evaluate conditions for code execution.
• Switch statement: Perform different actions based on a variable's value.

PHP Functions

• User-defined functions are custom functions created for specific tasks.
• Built-in functions are pre-available and do not require additional coding.
  • Examples include strlen(), count(), date(), etc.

Creating Functions:
To define a function:

function functionName() {
  // code to execute
}

Call the function using:

functionName();