✍️ PHP Basics – Foundation of PHP Programming for Beginners

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🧲 Introduction – Why Learn PHP Basics First?

PHP (Hypertext Preprocessor) is a widely-used open-source scripting language designed specifically for web development. Understanding the basics of PHP is crucial for anyone aiming to build dynamic websites, work with databases, or create backend logic for web applications.

Mastering the basics allows you to:

• 💬 Understand PHP syntax and structure
• 🧠 Manage variables, data types, and type handling
• 🔎 Debug and inspect PHP code efficiently

🎯 In this guide, you’ll learn how to:

• Work with variables, constants, and type declarations
• Output content using echo and print
• Understand PHP typing, strings, and debugging tools

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📘 Topics Covered

🔖 Topic	📄 Description
💬 PHP Comments	Add single-line and multi-line annotations
🧺 PHP Variables	Declare and use $variable syntax
💱 PHP $ and $$ Variables	Understand variable variables in PHP
🔒 PHP Constants	Define immutable values using define() or const
🎭 PHP Magic Constants	Use built-in predefined constants like __LINE__, __FILE__
📢 PHP Echo vs Print	Output values with echo and print
🔎 PHP var_dump	Inspect data types and values during debugging
🧬 PHP Data Types	Understand strings, integers, booleans, arrays, and more
🔤 PHP Strings	Manipulate text data with string functions
✅ PHP Booleans	Represent true/false logic
🔢 PHP Integers	Handle numeric data
🔄 PHP Type Casting	Convert between data types
♻️ PHP Type Juggling	Implicit type conversion by PHP
🧾 PHP Heredoc & Nowdoc	Handle multi-line string formatting
🎯 PHP Scalar Type Declarations	Declare function argument types
🎯 PHP Return Type Declarations	Define return types for functions
🛡️ PHP Strict Typing	Enforce type declarations with declare(strict_types=1)

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💬 PHP Comments – Write Developer Notes

// This is a single-line comment
# This is another single-line comment
/* This is a multi-line
   comment block */

✅ Comments help explain code, disable lines, and improve readability.

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🧺 PHP Variables – Store and Access Data

$name = "John";
$age = 25;

✅ Variables in PHP start with a $ and store data like strings, numbers, or arrays.

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💱 PHP $ and $$ – Variable Variables

$var = "name";
$$var = "John";
echo $name; // Outputs: John

✅ $$var creates a variable named $name.

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🔒 PHP Constants – Immutable Values

define("SITE_NAME", "Tech369Hub");
const VERSION = "1.0.0";

✅ Constants can’t be changed once defined. Ideal for config values.

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🎭 PHP Magic Constants – Built-in Constants

echo __FILE__; // Outputs full file path
echo __LINE__; // Outputs current line number

✅ Other examples: __DIR__, __FUNCTION__, __CLASS__

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📢 PHP Echo vs Print – Output Content

echo "Hello, world!";
print "Hello again!";

✅ Both output text, but echo is slightly faster and supports multiple parameters.

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🔎 PHP var_dump – Inspect Variables

$age = 25;
var_dump($age);

✅ Displays detailed info about a variable’s type and value.

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🧬 PHP Data Types – Understand Core Types

• String
• Integer
• Float
• Boolean
• Array
• Object
• NULL
• Resource

✅ PHP is dynamically typed but supports explicit type declarations.

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🔤 PHP Strings – Handle Text Data

$str = "Hello";
echo strlen($str); // Outputs: 5
echo str_replace("H", "J", $str); // Outputs: Jello

✅ Supports single (') and double (") quoted strings.

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✅ PHP Booleans – True/False Logic

$loggedIn = true;
if ($loggedIn) {
  echo "Welcome!";
}

✅ Used in conditions and logic statements.

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🔢 PHP Integers – Whole Numbers

$score = 100;

✅ Can be positive, negative, or zero. Use is_int() to check.

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🔄 PHP Type Casting – Convert Types

$price = "50";
$price = (int)$price;

✅ Converts strings to integers, floats, etc.

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♻️ PHP Type Juggling – Implicit Conversion

$result = "10" + 5; // 15

✅ PHP automatically converts types during operations.

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🧾 PHP Heredoc & Nowdoc – Multi-line Strings

$text = <<<EOD
This is a multi-line
string using heredoc.
EOD;

✅ Use Heredoc for parsing variables, Nowdoc for raw strings.

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🎯 PHP Scalar Type Declarations

function add(int $a, int $b) {
  return $a + $b;
}

✅ Declares argument types for stricter code handling.

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🎯 PHP Return Type Declarations

function getName(): string {
  return "Alice";
}

✅ Ensures the function returns the specified type.

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🛡️ PHP Strict Typing

declare(strict_types=1);

✅ Forces strict type checking. Use at the top of your file for type-safe PHP.

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📘 Best Practices for PHP Basics

✅ Recommended	🚫 Avoid
Use comments for clarity	Don’t over-comment obvious code
Prefer constants for fixed values	Avoid redefining them
Use echo for output	Don’t mix echo and print unnecessarily
Cast values before math	Don’t rely only on type juggling
Enable strict types	Avoid loose comparisons in critical logic

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📌 Summary – Recap & Next Steps

Mastering PHP basics is the first step toward building full-featured dynamic websites. With knowledge of variables, constants, data types, and basic type enforcement, you’re ready to explore functions, control flow, and OOP in PHP.

🔍 Key Takeaways:

• Understand variables, data types, and output methods
• Use constants, comments, and type declarations effectively
• Familiarize yourself with debugging tools like var_dump and echo
• Use strict typing and scalar declarations for modern PHP development

⚙️ Real-World Relevance:
Used in CMS platforms, APIs, eCommerce sites, and enterprise backends across the globe.

➡️ Next Up: Dive into 🧰 PHP Control Structures – If, Switch, Loops, and Flow Control.

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❓ FAQs – PHP Basics

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❓ Are PHP variables case-sensitive?
✅ Yes. $Name and $name are treated as different variables.

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❓ What’s the difference between define() and const?
✅ define() is used globally, while const can be used inside classes and functions.

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❓ What are PHP magic constants?
✅ Predefined constants like __LINE__, __FILE__, etc., that return meta-information.

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❓ Should I use strict typing in PHP?
✅ Yes. Enabling strict_types leads to safer and more predictable code.

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❓ What is Heredoc used for?
✅ Heredoc is ideal for multi-line strings that require variable parsing.

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