PHP Overview

• PHP is a server-side scripting language used for creating dynamic websites.
• Despite claims of being obsolete, PHP powers approximately 78% of all websites, including popular platforms like Facebook, Wikipedia, and Flipkart.

History of PHP

• Originally stood for Personal Home Page; now it's a recursive acronym for PHP Hypertext Preprocessor.
• Development began in 1993 by Rasmus Laerdorf to manage his personal website.

Running PHP Code

• PHP can be embedded directly within HTML files by changing the file extension from .html to .php.
• Raw PHP code can be viewed in a web browser if not run on a server.
• Use XAMPP to execute PHP files:
  • Install XAMPP on major OS (including Linux).
  • Start the Apache server from the XAMPP control panel.
  • Create a folder in the htdocs directory for your PHP code.
  • Access the file via localhost/foldername/filename.php.

Basic PHP Syntax

• PHP code is written within <?php ... ?> tags.
• Use echo to display output; example: echo "PHP is great";
• Comments:
  • Single-line: // or #
  • Multi-line: /* ... */

Variables

• Declared using $VARIABLE_NAME = value;
• Case-sensitive (e.g., $var vs $Var).
• All elements except variables are case-insensitive.

Data Types

• PHP has 8 primary data types:
  • Integer: Whole numbers
  • Float: Decimal numbers
  • String: Sequence of characters (single or double quotes)
  • Boolean: Represents true/false (1 for true)
  • Array: Can store multiple values of different types.
    • Indexed Arrays: Accessed by numerical index (0, 1, 2...)
    • Associative Arrays: Key-value pairs.
  • Object: Supports Object-Oriented Programming (OOP) using class and new keywords.
  • Resource: Refers to external resources (e.g., files).
  • NULL: Represents a variable with no value.

Control Statements

Conditional Statements

• If Statement:
  • Syntax: if (condition) {...} else {...}
• Switch Statement:
  • Compares variable with multiple values; includes case and default.

Loops

• While Loop: Executes code while the condition is true.
• Do While Loop: Executes code at least once before checking the condition.
• For Loop: Runs code a specific number of times; syntax includes initialization, condition, and increment.
• For Each Loop: Iterates over arrays easily.

Functions

• Define functions using function functionName() {...}.
• Call functions by their name followed by parentheses. Function parameters can be used to pass values.