KY Php

12 min readAug 17, 2026

PART 1 — PHP Fundamentals

Q1. What is PHP?

English Answer:

PHP stands for PHP: Hypertext Preprocessor. It is an open-source, server-side scripting language mainly used for developing dynamic websites and web applications.

PHP code executes on the server, and the generated result is sent to the browser.

Hinglish:

PHP ek server-side scripting language hai. PHP code browser mein directly execute nahi hota; server par execute hota hai aur browser ko output milta hai.

Example:

<?php

echo "Hello World";

?>

Interview Follow-up:

Q. Is PHP frontend or backend?

Answer: PHP is primarily a backend/server-side language.

Q2. Why is PHP called a server-side language?

English Answer:

PHP is called a server-side language because PHP code is executed on the web server before the response is sent to the user’s browser.

Hinglish:

Browser PHP code ko directly execute nahi karta. Request server par jaati hai, PHP server par execute hoti hai aur server HTML/JSON etc. response browser ko bhejta hai.

Flow:

Browser

↓

Request

↓

PHP Server

↓

PHP executes

↓

Response

↓

Browser

Q3. What are the main features of PHP?

English Answer:

The main features of PHP include:

Open-source
Free to use
Server-side execution
Cross-platform support
Database support
Object-oriented programming support
Easy integration with HTML
Large community and ecosystem

Hinglish:

PHP free aur open-source hai, Windows/Linux/macOS par run ho sakti hai, databases ke saath easily kaam karti hai aur OOP support karti hai.

Q4. What is the difference between PHP and JavaScript?

English Answer:

PHP is primarily a server-side language, while JavaScript traditionally runs in the browser and can also run on the server using environments such as Node.js.

Hinglish:

PHP        → Mainly Backend

JavaScript → Frontend + Backend

PHP server-side processing ke liye commonly use hoti hai, while JavaScript browser-side interaction ke liye commonly use hoti hai.

Follow-up:

Q. Can PHP work with React?

Yes. React can communicate with PHP through APIs, usually exchanging JSON data.

Q5. How do you write PHP code?

English Answer:

PHP code is generally written inside PHP tags.

Code:

<?php

echo "Hello PHP";

?>

Hinglish:

PHP code normally <?php se start hota hai.

Q6. What is a PHP variable?

English Answer:

A variable is used to store data in PHP. PHP variables start with the $ symbol.

Code:

$name = "Rahul";

$age = 25;

$price = 500.50;

Hinglish:

Variable data ko temporarily store karne ke liye use hota hai aur PHP mein $ se start hota hai.

Q7. What are the rules for naming variables in PHP?

English Answer:

A PHP variable:

Must start with $
Must start with a letter or underscore after $
Cannot start with a number
Can contain letters, numbers and underscores
Variable names are case-sensitive

Example:

$name = "Rahul";

$_name = "Rahul";

$name1 = "Rahul";

Invalid:

$1name = "Rahul";

Hinglish:

Variable $ se start hona chahiye aur $ ke baad number se start nahi kar sakte.

Q8. Are PHP variables case-sensitive?

English Answer:

Yes, PHP variable names are case-sensitive.

$name = "Rahul";

echo $name;

// $Name is a different variable

Hinglish:

$name aur $Name PHP ke liye different variables hain.

Q9. What are PHP data types?

English Answer:

PHP supports several data types, including:

String
Integer
Float
Boolean
Array
Object
NULL
Resource

Hinglish:

PHP mein different types ka data store karne ke liye different data types hote hain.

Q10. What is a String?

English Answer:

A string is a sequence of characters.

Code:

$name = "Rahul";

$message = 'Hello';

Hinglish:

Text ko string kehte hain.

Q11. What is an Integer?

English Answer:

An integer is a whole number without a decimal point.

Example:

$age = 25;

$count = 100;

Hinglish:

Without decimal wale whole numbers integer hote hain.

Q12. What is a Float?

English Answer:

A float is a number containing a decimal point.

Example:

$price = 99.99;

$rating = 4.5;

Hinglish:

Decimal numbers ko float kehte hain.

Q13. What is a Boolean?

English Answer:

A Boolean represents one of two values: true or false.

Example:

$isLoggedIn = true;

$isAdmin = false

Hinglish:

Boolean mein mainly do values hoti hain:

true

false

Q14. What is NULL in PHP?

English Answer:

NULL represents a variable with no value.

Example:

$name = NULL;

Hinglish:

Jab variable ke paas koi value nahi hoti, to uski value NULL ho sakti hai.

Q15. What is an array?

English Answer:

An array is a data structure that can store multiple values in a single variable.

Example:

$names = ["Rahul", "Amit", "Rohit"];

Hinglish:

Ek variable ke andar multiple values store karni ho to array use karte hain.

Q16. What is an object in PHP?

English Answer:

An object is an instance of a class. It contains properties and methods defined by the class.

Example:

class User {

public $name;

$user = new User();

$user->name = "Rahul";

Hinglish:

Class ek blueprint hoti hai aur us class se banaya hua actual instance object hota hai.

Q17. What is type casting?

English Answer:

Type casting is the process of converting a value from one data type to another.

Example:

$value = "100";

$number = (int)$value;

echo $number;

Hinglish:

String ko integer, float ko integer etc. mein convert karna type casting hai.

Q18. What is type juggling?

English Answer:

Type juggling is PHP’s automatic conversion of a value from one type to another when required by an operation.

Example:

$num = "10";

$result = $num + 5;

PHP can convert the numeric string for the arithmetic operation.

Hinglish:

PHP zarurat ke according datatype automatically convert kar sakti hai. Isko type juggling kehte hain.

Q19. What is the difference between `==` and `===`?

English Answer:

== compares values after type conversion when necessary, while === compares both value and data type.

Example:

5 == "5";     // true

5 === "5";    // false

Hinglish:

==  → Value compare

=== → Value + Data Type compare

Interview Tip:

Interview mein === ko generally safer comparison operator ke roop mein explain karna.

Q20. What is `echo` in PHP?

English Answer:

echo is a language construct used to output data.

Example:

echo "Hello";

echo $name;

Hinglish:

Browser ko output bhejne ke liye echo commonly use karte hain.

Q21. What is `print` in PHP?

English Answer:

print is also used to output data. Unlike echo, it returns 1 and accepts one argument.

Example:

print "Hello";

Hinglish:

print bhi output ke liye use hota hai, lekin echo zyada commonly use kiya jata hai.

Q22. What is the difference between echo and print?

English Answer:

echoprintLanguage constructLanguage constructCan accept multiple argumentsAccepts one argumentDoes not return a valueReturns 1Commonly used for outputAlso used for output

Hinglish:

Dono output ke liye use hote hain, lekin practical PHP code mein echo bahut common hai.

Q23. What are constants in PHP?

English Answer:

A constant is a value that cannot be changed during script execution.

Example:

define("SITE_NAME", "My Website");

echo SITE_NAME;

Or:

const SITE_NAME = "My Website";

Hinglish:

Aisi value jo program ke execution ke during change nahi karni ho, uske liye constant use kar sakte hain.

Q24. What is the difference between `const` and `define()`?

English Answer:

Both can create constants, but they have different syntax and language behavior. const is part of PHP's language syntax and can be used for class constants, while define() is a function that defines a constant at runtime.

Hinglish:

Dono constants banane ke liye use hote hain, lekin const language construct hai aur class constants ke liye bhi use hota hai.

Q25. What are magic constants?

English Answer:

Magic constants are predefined constants whose values can change depending on where they are used.

Examples include:

__FILE__

__DIR__

__LINE__

__FUNCTION__

__CLASS__

__METHOD__

__NAMESPACE__

Hinglish:

PHP ke special predefined constants ko magic constants kehte hain.

Example:

echo __FILE__;

Current PHP file ka path provide kar sakta hai.

Q26. What are operators in PHP?

English Answer:

Operators are symbols used to perform operations on values.

Common types include:

Arithmetic
Assignment
Comparison
Logical
Increment/Decrement
String
Conditional

Hinglish:

Values ke saath operation perform karne ke liye operators use hote hain.

Q27. What are arithmetic operators?

English Answer:

+   Addition

-   Subtraction

*   Multiplication

/   Division

%   Modulus

**  Exponentiation

Example:

$a = 10;

$b = 3;

echo $a + $b;

echo $a % $b;

Hinglish:

Mathematical calculations ke liye arithmetic operators use hote hain.

Q28. What are comparison operators?

English Answer:

Comparison operators compare two values.

Examples:

==

===

!=

!==

>=

<=

Hinglish:

Do values ko compare karne ke liye comparison operators use karte hain.

Q29. What are logical operators?

English Answer:

Logical operators are used to combine or negate conditions.

&&  AND

||  OR

!   NOT

Example:

if ($age >= 18 && $isVerified) {

echo "Allowed";

Hinglish:

Multiple conditions ko combine karne ke liye logical operators use hote hain.

Q30. What is the ternary operator?

English Answer:

The ternary operator is a short form of a simple if-else expression.

Example:

$status = ($age >= 18) ? "Adult" : "Minor";

Hinglish:

Normal:

if ($age >= 18) {

$status = "Adult";

} else {

$status = "Minor";

Ternary:

$status = ($age >= 18) ? "Adult" : "Minor";

Q31. What is the null coalescing operator?

English Answer:

The null coalescing operator ?? returns the first value if it exists and is not NULL; otherwise it returns the second value.

Example:

$name = $_GET['name'] ?? "Guest";

Hinglish:

Agar $_GET['name'] available hai to wo milega, warna "Guest" milega.

Q32. What is `isset()`?

English Answer:

isset() checks whether a variable is set and is not NULL.

Example:

if (isset($name)) {

echo $name;

Hinglish:

Check karna ho ki variable exist/set hai aur NULL nahi hai, to isset() use karte hain.

Q33. What is `empty()`?

English Answer:

empty() checks whether a variable contains an empty or false-like value.

Example:

if (empty($name)) {

echo "Name is empty";

Hinglish:

Variable empty hai ya false-like value rakhta hai ya nahi, ye check karne ke liye empty() use hota hai.

Q34. Difference between `isset()` and `empty()`?

English Answer:

isset() checks whether a variable exists and is not NULL.

Get Rahul Jingar’s stories in your inbox

Join Medium for free to get updates from this writer.

Remember me for faster sign in

empty() checks whether a value is considered empty.

Hinglish:

isset() → Set hai + NULL nahi?

empty() → Empty hai?

Interview Follow-up:

Q. What happens with isset($x) if $x = null?

Answer: It returns false.

Q35. What is `unset()`?

English Answer:

unset() destroys a variable or removes an array element.

Example:

$name = "Rahul";

unset($name);

Hinglish:

Variable ko remove/destroy karne ke liye unset() use hota hai.

Q36. What is variable scope?

English Answer:

Variable scope defines where a variable can be accessed.

PHP commonly has:

Local scope
Global scope
Static scope

Hinglish:

Variable program ke kis area mein accessible hai, usko variable scope kehte hain.

Q37. What is a local variable?

English Answer:

A variable declared inside a function generally has local scope and can be accessed within that function.

Example:

function test() {

$name = "Rahul";

echo $name;

Hinglish:

Function ke andar banaya variable normally us function ke andar hi accessible hota hai.

Q38. What is a global variable?

English Answer:

A variable declared outside a function has global scope. It is not automatically available inside functions unless explicitly accessed.

Example:

$name = "Rahul";

function test() {

global $name;

echo $name;

Hinglish:

Function ke bahar declared variable global scope mein hota hai. Function ke andar use karne ke liye global ya $GLOBALS use kar sakte hain.

Q39. What is the `global` keyword?

English Answer:

The global keyword allows a function to access a variable defined in the global scope.

Example:

$name = "Rahul";

function showName() {

global $name;

echo $name;

Hinglish:

Function ke bahar wale variable ko function ke andar access karna ho to global use kar sakte hain.

Q40. What is `$GLOBALS`?

English Answer:

$GLOBALS is a superglobal array containing references to variables in the global scope.

Example:

$name = "Rahul";

function test() {

echo $GLOBALS['name'];

Hinglish:

Global variables ko $GLOBALS ke through bhi access kar sakte hain.

Q41. What is a conditional statement?

English Answer:

Conditional statements execute code based on whether a condition is true or false.

Common conditional statements include:

if

if-else

elseif

switch

match

Hinglish:

Condition ke according different code execute karna ho to conditional statements use karte hain.

Q42. What is an `if` statement?

English Answer:

The if statement executes a block of code when a condition is true.

Example:

$age = 20;

if ($age >= 18) {

echo "Adult";

Hinglish:

Condition true hone par code execute hota hai.

Q43. What is the difference between `if-else` and `elseif`?

English Answer:

if-else provides an alternative block when the if condition is false. elseif allows multiple conditions to be checked sequentially.

Example:

if ($marks >= 90) {

echo "A";

} elseif ($marks >= 60) {

echo "B";

} else {

echo "C";

Hinglish:

Multiple conditions check karni ho to elseif useful hota hai.

Q44. What is a switch statement?

English Answer:

A switch statement is used to execute different blocks based on the value of an expression.

Example:

$day = 1;

switch ($day) {

case 1:

echo "Monday";

break;

case 2:

echo "Tuesday";

break;

default:

echo "Invalid";

Hinglish:

Ek value ke multiple possible cases ho to switch useful hota hai.

Q45. What is match expression in PHP?

English Answer:

match is an expression that compares a value strictly and returns a result.

Example:

$day = 1;

$result = match ($day) {

1 => "Monday",

2 => "Tuesday",

default => "Invalid"

};

echo $result;

Hinglish:

match modern PHP mein value matching ke liye use hota hai. Ye strict comparison karta hai aur result return karta hai.

Q46. Difference between `switch` and `match`?

English Answer:

switchmatchStatementExpressionUses loose comparison behaviorUses strict comparisonUsually uses breakNo break requiredDoes not directly return a value in the same wayReturns a valueOlder/common syntaxModern PHP feature

Hinglish:

Simple words mein:

switch → Traditional

match  → Modern + strict + value return

Q47. What is a loop?

English Answer:

A loop repeatedly executes a block of code while a condition is satisfied or while elements remain to be processed.

Types:

for

while

do-while

foreach

Hinglish:

Same code ko repeatedly execute karne ke liye loop use hota hai.

Q48. What is a `for` loop?

English Answer:

A for loop is commonly used when the number of iterations is controlled by a counter.

Example:

for ($i = 1; $i <= 5; $i++) {

echo $i;

Hinglish:

Jab pata ho ki loop ko kitni baar chalana hai, for loop useful hota hai.

Q49. What is a `while` loop?

English Answer:

A while loop repeatedly executes code as long as its condition remains true.

Example:

$i = 1;

while ($i <= 5) {

echo $i;

$i++;

Hinglish:

Jab tak condition true hai tab tak loop chalta rahega.

Q50. What is a `foreach` loop?

English Answer:

foreach is commonly used to iterate over arrays and other iterable values.

Example:

$names = ["Rahul", "Amit", "Rohit"];

foreach ($names as $name) {

echo $name;

Hinglish:

Array ke har element ko one-by-one access karne ke liye foreach sabse commonly use hota hai.

🔥 Q51. Difference between `for` and `foreach`?

English Answer:

for is generally counter-based, while foreach is designed for iterating over arrays and iterable values.

Hinglish:

for

↓

Counter based

foreach

↓

Array/Iterable based

🔥 Q52. What are `break` and `continue`?

English Answer:

break terminates the current loop.

continue skips the current iteration and moves to the next iteration.

Example:

for ($i = 1; $i <= 5; $i++) {

if ($i == 3) {

continue;

echo $i;

Output:

Hinglish:

break    → Loop completely stop

continue → Current iteration skip

🔥 Q53. What is a function in PHP?

English Answer:

A function is a reusable block of code designed to perform a specific task.

Example:

function add($a, $b) {

return $a + $b;

echo add(10, 20);

Hinglish:

Function reusable code ka block hota hai. Ek baar bana ke multiple times use kar sakte hain.

Q54. What is the difference between parameter and argument?

English Answer:

A parameter is a variable defined in the function declaration. An argument is the actual value passed when calling the function.

Example:

function add($a, $b) {

return $a + $b;

add(10, 20);

Here:

$a, $b    → Parameters

10, 20    → Arguments

Hinglish:

Function banate waqt jo variables hain wo parameters hain. Function call karte waqt jo actual values dete hain wo arguments hain.

Q55. What is `return`?

English Answer:

return sends a value from a function back to the code that called the function.

Example:

function add($a, $b) {

return $a + $b;

$result = add(10, 20);

echo $result;

Hinglish:

return function se value bahar bhejne ke liye use hota hai.

Q56. Difference between `echo` and `return`?

English Answer:

echo outputs data, while return sends a value back from a function.

Hinglish:

echo

↓

Output dikhata hai

return

↓

Function se value return karta hai

Q57. What is a default parameter?

English Answer:

A default parameter has a predefined value that is used when the caller does not provide an argument.

Example:

function greet($name = "Guest") {

return "Hello " . $name;

echo greet();

Output:

Hello Guest

Hinglish:

Agar function call karte time value nahi doge to default value use hogi.

Q58. What is pass by value?

English Answer:

Pass by value means a copy of the variable’s value is passed to the function. Changes to the parameter do not normally modify the original variable.

Example:

function change($x) {

$x = 100;

$a = 10;

change($a);

echo $a;

Hinglish:

Normally function ko variable ki value ki copy milti hai, original variable directly change nahi hota.

Q59. What is pass by reference?

English Answer:

Pass by reference allows a function to work with the original variable using the & symbol.

Example:

function change(&$x) {

$x = 100;

$a = 10;

change($a);

echo $a;

Output:

Hinglish:

& use karne par function original variable ko modify kar sakta hai.

Q60. What is an anonymous function?

English Answer:

An anonymous function is a function without a name. It can be assigned to a variable or passed as a callback.

Example:

$greet = function ($name) {

return "Hello " . $name;

};

echo $greet("Rahul");

Hinglish:

Jis function ka naam nahi hota usko anonymous function kehte hain.

Rahul Jingar

KY Php

PART 1 — PHP Fundamentals

Q1. What is PHP?

English Answer:

Hinglish:

Example:

Interview Follow-up:

Q2. Why is PHP called a server-side language?

English Answer:

Hinglish:

Flow:

Q3. What are the main features of PHP?

English Answer:

Hinglish:

Q4. What is the difference between PHP and JavaScript?

English Answer:

Hinglish:

Follow-up:

Q5. How do you write PHP code?

English Answer:

Code:

Hinglish:

Q6. What is a PHP variable?

English Answer:

Code:

Hinglish:

Q7. What are the rules for naming variables in PHP?

English Answer:

Example:

Hinglish:

Q8. Are PHP variables case-sensitive?

English Answer:

Hinglish:

Q9. What are PHP data types?

English Answer:

Hinglish:

Q10. What is a String?

English Answer:

Code:

Hinglish:

Q11. What is an Integer?

English Answer:

Example:

Hinglish:

Q12. What is a Float?

English Answer:

Example:

Hinglish:

Q13. What is a Boolean?

English Answer:

Example:

Hinglish:

Q14. What is NULL in PHP?

English Answer:

Example:

Hinglish:

Q15. What is an array?

English Answer:

Example:

Hinglish:

Q16. What is an object in PHP?

English Answer:

Example:

Hinglish:

Q17. What is type casting?

English Answer:

Example:

Hinglish:

Q18. What is type juggling?

English Answer:

Example:

Hinglish:

Q19. What is the difference between == and ===?

English Answer:

Example:

Hinglish:

Interview Tip:

Q20. What is echo in PHP?

English Answer:

Q19. What is the difference between `==` and `===`?

Q20. What is `echo` in PHP?

Q21. What is `print` in PHP?

Q24. What is the difference between `const` and `define()`?

Q32. What is `isset()`?

Q33. What is `empty()`?

Q34. Difference between `isset()` and `empty()`?

Q35. What is `unset()`?

Q39. What is the `global` keyword?