Introduction to PHP Programming

Introduction to Web Development

• PHP stands for Hypertext Preprocessor
• PHP is a server-side scripting language that can be embedded into HTML
• It appeared in the market in 1995, and the latest version is 7.4.0 (November 28, 2019)
• PHP is an object-oriented language that is interpreted and open-source
• PHP is platform-independent and can be used on Windows, Mac, Linux and Unix operating systems
• PHP is faster than ASP and JSP

Features of PHP

• PHP has a faster processing speed and better performance than other scripting languages
• It is open source, meaning it can be downloaded and used for free
• It has a clear syntax that is easy to understand
• It can be easily embedded into HTML tags and scripts
• PHP is a general-purpose language that supports MySQL, SQLite, ODBC and many other databases
• It is loosely-typed, which means that you don't need to declare data types for variables
• It has predefined error handling mechanisms
• PHP provides a high level of security
• PHP is compatible with various web servers such as Apache, Netscape, Microsoft, etc.
• PHP has a very large community with extensive documentation

PHP Fundamentals

• PHP code starts with an opening tag <?php and ends with a closing tag ?>
• PHP is partially case-sensitive. It is case-insensitive for keywords, user-defined functions, and class names
• PHP is case-sensitive for variables

Echo and Print

• echo is a language construct and a statement that can be used with or without parenthesis

• echo has no return value

• echo can pass multiple strings separated by a comma (,)

• echo is faster than the print statement

• print is a language construct and a statement that can be used with or without parenthesis

• print returns 1

• print cannot pass multiple strings

• print is slower than the echo statement

Statements

• Statements consist of one or more expressions
• Statements always end with a semicolon (;)
• Statements can be simple or compound
• Compound statements use curly brackets ({}) to mark a block of code

Whitespace and Line Breaks

• Whitespace and line breaks have no special meaning in PHP
• Whitespace and line breaks are equivalent to each other

Variables

• Variables start with a dollar sign ($)
• Variable names can contain alphanumeric characters and underscores
• Variable names should start with a letter or underscore
• Double dollar signs ($$) refer to a reference inside a variable

Constants

• There are two ways to define constants:
  • define() function: define(name, value, case-insensitive)
  • const keyword: const message = "1";
• echo constant() prints the value of a constant

Data Types

• Scalar (Pre-defined): contain a single value:
  • Boolean
  • Integer
  • Float
  • String
• Compound (User-defined): contain multiple values:
  • Array
  • Object
• Special Types:
  • Resource
  • Null

var_dump()

• Displays type and value
• var_dump() is a function that displays the data type and value of a variable

Comments

• Single-line comments: //
• Multi-line comments: /* */

PHP Operators

• Arithmetic: +, -, *, /, %, **
• Assignment: =, +=, -=, *=, /=, %=, **=, .=
• Bitwise: &, |, ^, ~, <<, >>
• Comparison: ==, !=, <, >, <=, >=, ===, !==
• Increment/Decrement: ++, --
• Logical: &&, ||, !
• String: .
• Array: [], array(), count(), in_array()
• Type: gettype(), isset(), empty(), unset(), is_array(), is_string(), is_int(), is_float(), is_bool(), is_null()
• Execution: include(), require(), include_once(), require_once()
• Error Control: @

Spaceship Operator

• Spaceship (<=>) operator returns:
  • -1 if less than
  • 0 if equal
  • 1 if greater than

Concatenation and Assignment

• .= concatenates two strings and assigns the result to the left-hand operand

PHP Control Structures

• If:
  • if (condition) { statement; }
• Else-if:
  • else if (condition) { statement; }
• If-else-if:
  • Combines if and else if
• Nested if:
  • An if statement inside another if statement
• Switch Statement:
  • switch (expression) { case value: statement; break; ... default: statement; }

Looping

• For Loop:
  • for (start; condition; increment) { statement; }
• While Loop:
  • while (expression) { statement; }
• Do-While Loop:
  • do { statement; } while (expression);

Jumping Statements

• Break:
  • Ends the loop
• Continue:
  • Skips the current iteration of the loop

Installing PHP

• Required Softwares
  • PHP
  • Web server that supports PHP (Apache)
  • Database server (MySQL)
• Installation Packages:
  • WAMP - Windows
  • LAMP - Linux
  • MAMP - Mac
  • SAMP - Solaris
  • FAMP - FreeBSD
  • XAMPP - Cross platform (Apache, MySQL, PHP, Perl)

XAMPP Control Panel

• Modules included: Apache, MySQL, FileZilla, Mercury, Tomcat

Two Main Applications of PHP

• Server-side Scripting:
  • Dynamic websites and web applications
• Command-Line Scripting:
  • Run PHP scripts from the command line for administrative tasks

Advantages of PHP

• Simple and easy to learn
• Fast
• Stable
• Open-source and free
• Large and supportive community

This quiz covers the basics of PHP programming, including its features, history, and advantages over other scripting languages. You'll learn about PHP's syntax, security features, and its compatibility with various operating systems. Test your knowledge on this essential web development tool.