2. PHP Basics

🔹 1. Variables & Data Types

✅ Variables

Variables are used to store data.

👉 In PHP, variables start with $

$name = "Aditya";
$age = 25;

✅ Rules:

• Must start with $
• Cannot start with a number
• Case-sensitive ($name ≠ $Name)

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✅ Data Types in PHP

Type	Example	Description
String	"Hello"	Text
Integer	10	Whole numbers
Float	10.5	Decimal numbers
Boolean	true/false	True or false
Array	["a", "b"]	Multiple values
Object	new ClassName()	Complex data

$name = "Aditya";   // String
$age = 25;         // Integer
$price = 99.99;    // Float
$isActive = true;  // Boolean

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🔹 2. Constants

Constants are values that cannot be changed once defined.

define("SITE_NAME", "SOA Technology");
echo SITE_NAME;

✅ Rules:

• No $ symbol
• Always global
• Value cannot be modified

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🔹 3. Operators

Operators are used to perform operations on variables

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➤ Arithmetic Operators

Operator	Meaning
+	Addition
-	Subtraction
*	Multiplication
/	Division
%	Modulus

$a = 10;
$b = 5;
echo $a + $b; // 15

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➤ Comparison Operators

Operator	Meaning
==	Equal
===	Equal (value + type)
!=	Not equal
>	Greater
<	Less

$a = 10;
$b = "10";var_dump($a == $b);  // true
var_dump($a === $b); // false

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➤ Logical Operators

Operator	Meaning
&&	AND
`
!	NOT

$x = true;
$y = false;var_dump($x && $y); // false

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🔹 4. Echo vs Print

Both are used to display output

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✅ echo

• Faster
• Can print multiple values

echo "Hello ", "World";

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✅ print

• Slower than echo
• Returns value (1)

print "Hello World";

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🔥 Key Difference

Feature	echo	print
Speed	Faster	Slower
Multiple arguments	Yes	No
Return value	No	Yes (1)

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🔹 5. Comments

Comments are used to explain code (ignored by PHP)

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➤ Single-line comment

// This is a comment
# This is also a comment

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➤ Multi-line comment

/*
This is a
multi-line comment
*/

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✅ Summary

• Variables store data ($name)
• Data types define the kind of data
• Constants are fixed values
• Operators perform operations
• echo & print show output
• Comments explain code