Php MCQ Questions with Answers

1.What is the difference between == and === in PHP?

=== compares value and type; == coerces types before comparing

== compares references

=== only works on integers

They are identical

2.In PHP 8, what is the result of 0 == "foo"?

true

false

null

A fatal error

3.What is the difference between require and include?

require causes a fatal error and halts if the file is missing; include emits a warning and continues

include halts execution

They are identical

require only works with classes

4.Which is the strongest defence against SQL injection in PHP?

mysqli_real_escape_string on every value

Prepared statements with bound parameters

Removing quotes from input

Limiting input length

5.Which PDO attribute should be set so query failures raise exceptions?

PDO::ATTR_ERRMODE set to PDO::ERRMODE_EXCEPTION

PDO::ATTR_PERSISTENT

PDO::ATTR_TIMEOUT

PDO::ATTR_CASE

6.Why should PDO::ATTR_EMULATE_PREPARES be set to false?

To improve performance only

So the database performs the preparation, giving genuine parameterisation

To enable persistent connections

To support more drivers

7.Which function correctly escapes output for HTML context?

strip_tags()

htmlspecialchars($v, ENT_QUOTES, 'UTF-8')

addslashes()

urlencode()

8.Which PHP function should be used to hash a user password?

md5()

sha1()

password_hash()

crc32()

9.Which function verifies a password against a stored hash?

password_verify()

hash_compare()

md5_check()

strcmp()

10.What must be called immediately after a successful login to prevent session fixation?

session_destroy()

session_regenerate_id(true)

session_unset()

session_write_close()

11.Why do PHP sessions break behind a load balancer by default?

Sessions expire too quickly

Session files are stored on the local disk of one server

Cookies are not sent

PHP disables sessions in clusters

12.What does Composer's autoload PSR-4 mapping do?

Loads all files at startup

Maps namespace prefixes to directories so classes load on demand

Compiles PHP to bytecode

Downloads dependencies at runtime

13.Which command should be used to install dependencies during deployment?

composer update

composer install --no-dev --optimize-autoloader

composer require

composer dump

14.What is the difference between an interface and an abstract class in PHP?

An interface declares method signatures only and a class may implement many; a class may extend only one abstract class

An abstract class cannot contain methods

Interfaces can hold state

They are identical

15.What is a trait in PHP used for?

Reusing methods across classes that share no common ancestor

Defining constants

Creating database models

Handling exceptions

16.In PHP 7 and later, which type should be caught to handle both exceptions and errors?

Exception

Error

Throwable

RuntimeException

17.What does the finally block guarantee?

It runs only when no exception occurs

It always runs, whether or not an exception was thrown

It suppresses the exception

It runs before the try block

18.Which superglobal contains data submitted via an HTML form using the POST method?

$_GET

$_POST

$_REQUEST

$_SERVER

19.Why is POST not inherently more secure than GET?

Both are plaintext without HTTPS

POST data is always encrypted

GET is encrypted by default

POST bypasses the network

20.What is the correct approach to validating a file upload?

Trust the file extension supplied by the browser

Verify the real MIME type, cap the size, rename the file and store it outside the web root

Only check the file size

Rename the file to .php for processing

21.What does OPcache do?

Caches database query results

Caches compiled PHP bytecode so scripts are not recompiled on every request

Caches HTTP responses

Caches session data

22.Which PHP 8 feature reduces boilerplate by declaring and assigning properties in the constructor signature?

Named arguments

Constructor property promotion

Union types

Attributes

23.What does the readonly property modifier introduced in PHP 8.1 do?

Prevents the property being written after initialisation

Makes the property private

Prevents the class being extended

Caches the property value

24.How does the match expression differ from a switch statement?

match returns a value, uses strict comparison and has no fall-through

match uses loose comparison

switch returns a value

They are identical

25.What does declare(strict_types=1) do?

Enables type coercion

Enforces exact type matching for scalar type declarations in that file

Disables all type checking

Enables strict error reporting

26.Which of these correctly checks whether an array key exists, including when its value is null?

isset($arr['key'])

array_key_exists('key', $arr)

empty($arr['key'])

in_array('key', $arr)

27.What is the difference between echo and print in PHP?

echo can take multiple arguments and returns nothing; print takes one argument and returns 1

print is faster

echo returns a value

They cannot both output strings

28.Which function safely compares two hashes or tokens?

==

strcmp()

hash_equals()

similar_text()

29.What is a namespace in PHP used for?

Preventing name collisions between classes and functions from different libraries

Improving performance

Encrypting class names

Defining access modifiers

30.Which is an appropriate use of a static method?

A factory or utility function that needs no instance state

Storing per-request user data

Managing database connections per user

Holding form state

31.What does the spaceship operator (<=>) return?

-1, 0 or 1 depending on whether the left is less than, equal to or greater than the right

true or false

The larger of two values

The difference between two numbers

32.Which PHP setting must be disabled in production to avoid leaking stack traces?

log_errors

display_errors

error_reporting

memory_limit

33.What is the purpose of a CSRF token in a PHP form?

To verify that the request originated from your own site

To encrypt form data

To validate the email format

To compress the request

34.Which array function applies a callback to every element and returns a new array?

array_filter()

array_map()

array_reduce()

array_walk()

35.What does the null coalescing operator (??) do?

Returns the right operand when the left is null or undefined

Converts null to zero

Throws an error on null

Checks whether a variable is set only

36.What is an enum in PHP 8.1 used for?

Defining a fixed set of named, type-safe values

Enumerating array keys

Iterating over collections

Declaring constants in an interface

37.Which of these best describes PSR-12?

A coding style standard for PHP

An autoloading specification

A logging interface

An HTTP message interface

38.Which tool performs static analysis on PHP code to find bugs without running it?

PHPUnit

PHPStan

Composer

Xdebug

39.What does the nullsafe operator (?->) do?

Returns null instead of throwing when calling a method on null

Suppresses all errors

Converts null to an empty string

Declares a nullable property

40.Which of these is the correct return type declaration for a function that may return an integer or null?

function f(): ?int

function f(): int?

function f(): nullable int

function f(): void

41.What is the most common cause of an unexpectedly slow PHP application?

Using double quotes instead of single quotes

Inefficient database queries such as N+1 patterns and missing indexes

Excessive comments

Long variable names

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Php MCQ With Answers

Php MCQ

1.What is the difference between == and === in PHP?

2.In PHP 8, what is the result of 0 == "foo"?

3.What is the difference between require and include?

4.Which is the strongest defence against SQL injection in PHP?

5.Which PDO attribute should be set so query failures raise exceptions?

6.Why should PDO::ATTR_EMULATE_PREPARES be set to false?

7.Which function correctly escapes output for HTML context?

8.Which PHP function should be used to hash a user password?

9.Which function verifies a password against a stored hash?

10.What must be called immediately after a successful login to prevent session fixation?

11.Why do PHP sessions break behind a load balancer by default?

12.What does Composer's autoload PSR-4 mapping do?

13.Which command should be used to install dependencies during deployment?

14.What is the difference between an interface and an abstract class in PHP?

15.What is a trait in PHP used for?

16.In PHP 7 and later, which type should be caught to handle both exceptions and errors?

17.What does the finally block guarantee?

18.Which superglobal contains data submitted via an HTML form using the POST method?

19.Why is POST not inherently more secure than GET?

20.What is the correct approach to validating a file upload?

21.What does OPcache do?

22.Which PHP 8 feature reduces boilerplate by declaring and assigning properties in the constructor signature?

23.What does the readonly property modifier introduced in PHP 8.1 do?

24.How does the match expression differ from a switch statement?

25.What does declare(strict_types=1) do?

26.Which of these correctly checks whether an array key exists, including when its value is null?

27.What is the difference between echo and print in PHP?

28.Which function safely compares two hashes or tokens?

29.What is a namespace in PHP used for?

30.Which is an appropriate use of a static method?

31.What does the spaceship operator (<=>) return?

32.Which PHP setting must be disabled in production to avoid leaking stack traces?

33.What is the purpose of a CSRF token in a PHP form?

34.Which array function applies a callback to every element and returns a new array?

35.What does the null coalescing operator (??) do?

36.What is an enum in PHP 8.1 used for?

37.Which of these best describes PSR-12?

38.Which tool performs static analysis on PHP code to find bugs without running it?

39.What does the nullsafe operator (?->) do?

40.Which of these is the correct return type declaration for a function that may return an integer or null?

41.What is the most common cause of an unexpectedly slow PHP application?

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