PHP Module 1: Introduction to PHP

Study Notes

PHP was developed by Rasmus Lerdorf in 1994/1995
Originally stood for Personal Home Page, later changed to Hypertext Preprocessor
Key features of PHP:
- Server-side scripting language
- Loosely typed language
- Many built-in libraries and functions
- Supports many databases
- Free and open source
Software requirements:
- Operating System: Windows, Linux, or Mac
- Web Server: Apache, Google Web Server, etc.
- Database: MySQL, Oracle, etc.
- Code Editor: Notepad++, Eclipse, Dreamweaver, etc.
To run PHP scripts:
- Install XAMPP/WAMP
- Start Apache and MySQL services
- Save PHP files in htdocs folder
- Access via localhost in browser
PHP syntax basics:
- PHP code is enclosed in <?php ?> tags
- Statements end with a semicolon
- echo and print are used for output
- Variables start with a $ symbol
- Comments: // for single line, /* */ for multi-line
PHP data types:
- Scalar: boolean, integer, float, string
- Compound: array, object
- Special: NULL, resource
Type casting:
- Changing variable types explicitly
- Examples: (int), (float), (string), (array), (object), etc.

Arithmetic operators: +, -, *, /, %, **
Assignment operators: =, +=, -=, *=, /=, %=, etc.
Comparison operators: ==, ===, !=, !==, <, >, etc.
Increment/Decrement operators: ++, --
Logical operators: &&, ||, !, and, or, xor
String operators: . (concatenation)
Array operators: +, ==, ===, !=, !==
Operator precedence and associativity:
- Understand order of operations
- Use parentheses to clarify intent
Control structures:
- Conditional: if, else, elseif, switch
- Loops: while, do-while, for, foreach
- Break, continue, goto statements
Alternative syntax:
- Replace { } with : and endif;, endwhile;, endfor;, etc.

Arrays:
- Indexed arrays: numeric keys
- Associative arrays: string keys
- Multidimensional arrays: arrays within arrays
Array functions:
- print_r() and var_dump() for debugging
- sort(), rsort(), asort(), arsort(), ksort(), krsort()
- unset(), explode(), implode()
Looping through arrays:
- foreach loop
User-defined functions:
- function keyword
- Parameters and return values
- Variable scope: global, local, static

Constants:
- define() function
Including files:
- include, require, include_once, require_once
Mathematical functions:
- rand(), ceil(), floor(), min(), max(), number_format()
String manipulation functions:
- strlen(), strpos(), strrev(), strtolower(), strtoupper(), substr()
- ucfirst(), ucwords(), trim(), ltrim(), rtrim(), strip_tags()
Date and time functions:
- date(), mktime(), strtotime()
- Date format characters (Y, m, d, H, i, s, etc.)

Superglobal variables:
- SERVER,_SERVER, SERVER,_GET, POST,_POST, POST,_REQUEST, COOKIE,_COOKIE, COOKIE,_SESSION, $_ENV
Form handling:
- Difference between GET and POST methods
- Processing form data
Cookies:
- setcookie() function
- Reading and deleting cookies
Sessions:
- session_start(), session_destroy()
- Setting and unsetting session variables
Regular expressions:
- preg_match() function
- Common regex patterns and modifiers
- Form validation using regex (e.g., email validation)

Introduction to databases:
- Definition: Ordered collection of information for quick access
- Structure: Tables, records, and fields
- Types: Flat-file vs. Relational databases
- Key concepts: Primary key, Foreign key, Normalization
MySQL basics:
- Open-source relational database management system
- Features: High availability, scalability, and performance