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  • 1.1 PHP Intro
  • 1.2 PHP Install
  • 1.3 PHP Syntax
  • 1.4 PHP Comments
  • 1.5 PHP Variables
  • 1.5.1 Variables Scope
  • 1.6 PHP Echo / Print
    •

    1.4 PHP Comments

  • 1.1 PHP Intro
  • 1.2 PHP Install
  • 1.3 PHP Syntax
  • 1.4 PHP Comments
  • 1.5 PHP Variables
  • 1.5.1 Variables Scope
  • 1.6 PHP Echo / Print
    •
  • 2.1 PHP Data Types
  • 2.2 PHP Strings
  • 2.3 PHP Numbers
  • 2.4 PHP Math
  • 2.5 PHP Constants
  • 2.6 PHP Casting
  • 2.7 PHP Magic Constants
    •
  • 3.1 PHP Operators
  • 3.2 PHP If Else Elseif
  • 3.3 PHP Switch
  • 3.4 PHP Loops
  • 3.4.1 While Loop
  • 3.4.2 Do While Loop
  • 3.4.3 For Loop
  • 3.4.4 Foreach Loop
  • 3.4.5 Break/Continue
  • 3.5 PHP Functions
    •
  • 4.1 PHP Arrays
  • 4.1.1 Indexed Arrays
  • 4.1.2 Associative Arrays
  • 4.1.3 Multidimensional Arrays
  • 4.1.4 Sorting Arrays
  • 4.2 PHP Superglobals
  • 4.2.1 $GLOBALS
  • 4.2.2 $_SERVER
  • 4.2.3 $_REQUEST
  • 4.2.4 $_POST
  • 4.2.5 $_GET
  • 4.3 PHP RegEx
    •
  • 5.1 PHP Form Handling
  • 5.2 PHP Form Validation
  • 5.3 PHP Form Required
  • 5.4 PHP Form URL / E-mail
  • 5.5 PHP Form Complete
    •
  • 6.1 PHP Date and Time
  • 6.2 PHP Include Files
  • 6.3 PHP File Handling
  • 6.4 PHP File Open/Read
  • 6.5 PHP File Create/Write
  • 6.6 PHP File Upload
  • 6.7 PHP Cookies
  • 6.8 PHP Sessions
  • 6.9 PHP Filters
  • 6.10 PHP Filters Advanced
  • 6.11 PHP Callback Functions
  • 6.12 PHP JSON
  • 6.13 PHP Exceptions
    •
  • 7.1 PHP What is OOP
  • 7.2 PHP Classes / Objects
  • 7.3 PHP Constructor
  • 7.4 PHP Destructor
  • 7.5 PHP Access Modifiers
  • 7.6 PHP Inheritance
  • 7.7 PHP Class Constants
  • 7.8 PHP Abstract Classes
  • 7.9 PHP Interfaces
  • 7.10 PHP Traits
  • 7.11 PHP Static Methods
  • 7.12 PHP Static Properties
  • 7.13 PHP Namespaces
  • 7.14 PHP Iterables
    •
  • 8.1 MySQL Database
  • 8.2 MySQL Connect
  • 8.3 MySQL Create DB
  • 8.4 MySQL Create Table
  • 8.5 MySQL Insert Data
  • 8.6 MySQL Get Last ID
  • 8.7 MySQL Insert Multiple
  • 8.8 MySQL Prepared
  • 8.9 MySQL Select Data
  • 8.10 MySQL Where
  • 8.11 MySQL Order By
  • 8.12 MySQL Delete Data
  • 8.13 MySQL Update Data
  • 8.14 MySQL Limit Data
    •
  • 9.1 PHP XML Parsers
  • 9.2 PHP SimpleXML Parser
  • 9.3 PHP SimpleXML - Get
  • 9.4 PHP XML Expat
  • 9.5 PHP XML DOM
    •
  • 10.1 AJAX Intro
  • 10.2 AJAX PHP
  • 10.3 AJAX Database
  • 10.4 AJAX XML
  • 10.5 AJAX Live Search
  • 10.6 AJAX Poll
  • My Poll
    •
    • A comment in PHP code is a line that is not executed as a part of the program. Its only purpose is to be read by someone who is looking at the code.
    • Comments can be used to:
      • Let others understand your code
      • Remind yourself of what you did - Most programmers have experienced coming back to their own work a year or two later and having to re-figure out what they did. Comments can remind you of what you were thinking when you wrote the code.
    • PHP supports several ways of commenting:
    Example 1: Syntax for single-line comments

    Syntax for single-line comments:

    <!DOCTYPE html>
<html>
<body>

<?php
// This is a single-line comment

# This is also a single-line comment
?>

</body>
</html>
    Example 2: Syntax for multiple-line comments:

    Syntax for multiple-line comments:

    <!DOCTYPE html>
<html>
<body>

<?php
/*
This is a multiple-lines comment block
that spans over multiple
lines
*/
?>

</body>
</html>
    Example 3: Using comments to leave out parts of the code:

    Using comments to leave out parts of the code:

    <!DOCTYPE html>
<html>
<body>

<?php
// You can also use comments to leave out parts of a code line
$x = 5 /* + 15 */ + 5;
echo $x;
?>

</body>
</html>

    PHP Fundamentals course home
    Module 1. Introduction to PHP

    Navigate this module
  • 1.1 PHP Intro
  • 1.2 PHP Install
  • 1.3 PHP Syntax
  • 1.4 PHP Comments
  • 1.5 PHP Variables
  • 1.5.1 Variables Scope
  • 1.6 PHP Echo / Print
    •

    Eventually the navigation links, above, will be replaced by these << (previous) and >> (next) buttons below.


    Animated PHP icons used in the buttons provided by ICONS8.COM. Smartphone icons created by Freepik - Flaticon

    Example files created in this module:
    My first PHP page - Hello World PHP Case Sensitivity - Hello World PHP Case Sensitivity - Color World Syntax for single-line comments Syntax for multiple-line comments: Using comments to leave out parts of the code: Declaring PHP Variables Output Variables part 1 Output Variables part 2 Output Variables part 3 Variable with global scope: Variable with local scope: PHP The global Keyword part 1 PHP The global Keyword part 2 PHP The static Keyword The PHP echo Statement part 1 The PHP echo Statement part 2 The PHP print Statement part 1 The PHP print Statement part 2