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Top PHP Interview Questions and Answers 2024

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Did you Know?

How PHP Started: A developer named Rasmus Lerdorf first made PHP to control his website. After improving it for months, he released the first official PHP version.

Who Uses PHP: About 80% of all websites use PHP, including big names like Facebook. It works on many operating systems.

Why PHP Is Popular: PHP powers over 240 million sites. Its open-source nature, flexibility, simplicity, and speed make PHP one of the top languages for web development today.

Top Answers to PHP Interview Questions

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PHP finds itself among the top languages because of its ability to have a large impact on the outcome with very little code. This amount of efficiency has been the main requirement for the past couple of years in the industry. Now, seeing this, companies across the globe are investing a good amount of money in hiring proficient PHP developers to fit these shoes and work effectively. These heavily asked top PHP core interview questions will give you the edge that is required to approach the questions effectively and answer them in a concise manner.

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PHP Basic Interview Questions for Freshers

1. What is PHP most used for?

PHP has a plethora of uses for developers and the ones mentioned below are some of the most widely used concepts that PHP offers:

  • With PHP, it becomes very easy to provide restricted access to the required content of the website.
  • It allows users to access individual cookies and set them as per requirement.
  • Database manipulation operations, such as addition, deletion, and modification, can be done easily.
  • Form handling, alongside features that involve file handling concepts and email integration, is used widely.
  • The system module allows users to perform a variety of system functions such as open, read, write, etc.

2. Is PHP a case-sensitive scripting language?

The answer to this is both yes and no. Variables and their declaration in PHP are completely case sensitive while function names are not.

For example, user-defined functions in PHP can be defined in uppercase but later referred to in lowercase, and it would still function normally.

Next up on these PHP interview questions for freshers, you need to understand what PEAR is.

3. What is the meaning of PEAR in PHP?

PEAR stands for PHP Extension and Application Repository. It is one of the frameworks and acting repositories that host all of the reusable PHP components. Alongside containing some of the PHP libraries, it also provides you with a simple interface in PHP to automatically install packages.

4. How is a PHP script executed?

PHP scripts can be easily executed from the command-line interface (CLI). The syntax is as follows:

php filename.php

Here, filename refers to the file that contains scripts. The extension .php is needed alongside the filename.

5. What are the types of variables present in PHP?

There are eight primary data types in PHP as shown below:

  • Array: A named and ordered collection of data
  • Boolean: A logical value (True or False)
  • Double: Floating point numbers such as 5.1525
  • Integer: Whole numbers without a floating point
  • Object: An instance of classes, containing data and functions
  • NULL: A special data type, supporting only the NULL data
  • Resource: Special variables that hold references to external resources
  • String: A sequence of characters such as, “Hello learners!”

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6. What are the main characteristics of a PHP variable?

Following are some of the most important aspects of the usage of variables in PHP:

  • Variables can be declared before the value assignment.
  • A variable value assignment happens using the ‘=’ operator.
  • Every variable in PHP is denoted with a $ (dollar) sign.
  • The value of a variable depends on its latest assigned value.
  • PHP variables are not intrinsic. There is no explicit declaration.

Next up on these PHP interview questions for freshers, you need to understand what NULL is.

7. What does the phrase ‘PHP escape’ mean?

PHP escape is a mechanism that is used to tell the PHP parser that certain code elements are different from the PHP code. This provides the basic means to differentiate a piece of PHP code from the other aspects of the program.

8. Differentiate between PHP4 and PHP5.

PHP4 PHP5
No support for static methods Allows the usage of static methods
Abstract classes cannot be declared Abstract classes can be declared
The method of call-by-value is used The method of call-by-reference is used
Constructors can have class names Constructors have separate names

9. What are some of the popular frameworks in PHP?

There are many frameworks in PHP that are known for their usage. Following are some of them:

  • CodeIgniter
  • CakePHP
  • Laravel
  • Zend
  • Phalcon
  • Yii 2

10. What is PHP?

PHP stands for Hypertext Preprocessor. It is an open-source,  general-purpose, scripting language that is especially used for web development.

11. Explain the PHP request-response cycle.

The PHP request-response cycle is a concept that explains how a web application processes incoming requests and generates responses that are later sent to the client.

12. What are some of the key features of PHP?

Some of the key features of PHP are:

  • It is completely open-source.
  • It is compatible with many databases, like MySQL, SQLite, etc.
  • It is platform-independent, that is, it can be run on any operating system like Linux, Unix, Windows, etc.
  • It is object-oriented, that is it supports object oriented functionalities like encapsulation, inheritance, abstraction, and polymorphism.

13. What are constants in PHP, and what is the syntax to define them?

In PHP, constants are like variables that cannot be changed during the execution of the script. They are used to store values that remain constant throughout the execution.

Ex.

define(name, value, case-insensitive);
Where, name = name of the constant
value = value of the constant
Case-sensitive takes in a boolean value

14. What is the difference between == and === operators in PHP?

“==” operator is used to check two values without checking datatypes.

“===” operator is used to do a strict check that also checks for datatypes along with values

15. What are superglobals in PHP?

Superglobal variables in PHP are predefined global variables. Global variables are accessible from any part of a PHP script. Some examples of superglobal variables are  $_GET, $_POST, $_REQUEST, $_FILES, $_COOKIE, $_SESSION, $_SERVER, $_ENV, and $GLOBALS.

PHP Interview Questions for Experienced

16. How does JavaScript interact with PHP?

JavaScript is a client-side programming language, while PHP is a server-side scripting language. PHP has the ability to generate JavaScript variables, and this can be executed easily in the browser, thereby making it possible to pass variables to PHP using a simple URL.

17. Does PHP interact with HTML?

Yes, HTML and PHP interaction is at the core of what makes PHP’s functionality. PHP scripts have the ability to generate HTML mode and move around information very easily.

PHP is a server-side scripting language, while HTML is a client-side language. This interaction helps bridge the gaps and use the best of both languages.

18. Differentiate between require() and require_once() functions.

require() require_once()
The inclusion and evaluation of files Includes files if they are not included before
Preferred for files with fewer functions Preferred when there are a lot of functions

19. What is the most used method for hashing passwords in PHP?

The crypt() function is widely used for this functionality as it provides a large amount of hashing algorithms that can be used. These algorithms include md5, sha1 or sha256.

PHP Interview Questions for 3 Years Experience

20. What are sessions and cookies in PHP?

Sessions are global variables that are stored on the server inside the architecture. Every single session is tagged with a unique server ID that is later used to work with the storage and retrieval of values.

Cookies are entities used to identify unique users in the architecture. It is a small file that the server plants into the client system. This is done to get useful information from the client for the development of various aspects of the server.

Let us now take a look at the advanced questions.

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21. Can a form be submitted in PHP without making use of a submit button?

Yes, a form can be submitted without the explicit use of a button. This is done by making use of the JavaScript submit() function easily.

Next up on this PHP developer interview questions, it is vital that you know about PHP in detail. Read on.

22. What are the different types of PHP errors?

There are three main types of errors in PHP. They are as follows:

  • Notice: A notice is a non-critical error that is not displayed to the user.
  • Warning: A warning is an error that is displayed to the user while the script is running.
  • Fatal error: This is the most critical type of error. A fatal error will cause immediate termination of the script.

23. What are PHP namespaces?

Namespaces are qualifiers that are used to group the classes that work together. They are usually used to encapsulate classes, interfaces, functions, and constants that perform similar tasks.

Syntax:  

namespace example;

This creates a namespace by the name of “example”

24. What are traits in PHP?

Traits are a kind of method that allows us to reuse the code. They provide a means to mitigate the constraints of single inheritance by allowing us to freely reuse sets of methods across multiple classes that exist in separate class hierarchies.

Check out the Web Development Interview Questions for Freshers.

25. Can you submit a form without reloading the page in PHP?

No, we cannot submit a form without reloading the page in PHP. As PHP is a server-side language, it requires a page reload to process the form data.

26. Explain the differences between abstract classes and interfaces.

Interfaces Abstract classes
Interfaces cannot have properties. Abstract classes can have properties.
All interfaces must be public. Abstract classes can be public or protected.
In the interface, we can only use public access specifiers. In abstract classes, we can use all access specifiers.

27. What are the differences between a session and a cookie?

Cookie Session
It is stored on the user’s web browser. It is stored server-side, that is, on the web server.
It lasts for a longer time, even after the user closes their browser. It lasts for a shorter period of time, usually only until the user closes their browser.
It can only hold a small amount of data, up to 4KB. It can hold a large amount of data, usually 64mb or 128mb.

PHP Interview Questions for 5 Years Experience

28. What is the difference between ASP.NET and PHP?

ASP.NET PHP
A programming framework A scripting language
Compiled and executed Interpreted mode of execution
Designed for use on Windows Platform independent

Also check out our blog on ASP.NET

29. How can you get the IP address of a client in PHP?

The IP address of a client, who is connected, can be obtained easily in PHP by making use of the following syntax:

$_SERVER["REMOTE_ADDR"];

30. Differentiate between GET and POST methods in PHP.

GET Method POST Method
The GET method can only send a maximum of 1024 characters simultaneously There is no restriction on the data size
GET does not support sending binary data POST supports binary data as well as ASCII
QUERY_STRING env variable is used to access the data that is sent The HTTP protocol and the header are used to push the data
The $_GET associative array is used to access the sent information The $_POST associative array is used to access the sent information here

31. How can you optimize the performance of PHP code?

A few of the points to improve the performance of a PHP code are:

  • Optimizing Code: Make your website’s code better to use less memory and make it faster for users.
  • Using HTTP/2: Switching to HTTP/2 makes your website faster because it can handle more requests at once.
  • Better Caching: Use techniques like network caching, HTTP caching, and database caching to make your website load faster for users who have visited before.
  • Improving Frontend: Make your website look better and easier to use by improving styles, adding more options and images, and creating more pages if needed.

Also check out Closures in JavaScript

32. What are closures in PHP?

Closures are small one-time use functions in PHP that can be passed around and used in other functions. They are helpful in avoiding writing larger wrapper functions just to pass to array functions, for example. 

The key aspects are:

  1. Compact, single-use functions.
  2. Can accept arguments and return values like normal functions.
  3. Can be assigned to variables and passed to other functions.
  4. Have access to variables from the parent scope.
  5. Help make the code more concise and readable.
  6. Used in array functions and callbacks.

33. How can you achieve data abstraction in PHP?

There are two main ways to approach abstraction:

1) Using Interfaces: 

   – Interfaces allow us to define common methods that a class must implement.

   – The interface only defines the method signatures and the class implements the logic.

   – This separates the interface from the implementation details

   – For example, a MailerInterface can define sendMail() method and classes implement the actual mail sending logic.

2) Using Abstract Classes:

   – Abstract classes allow us to have abstract methods without body

   – Any child class inheriting an abstract class must define the implementation of abstract methods. 

   – This enforces a common interface in all child classes

   – Additional non-abstract methods with implementation can also be defined.

   – So core logic can stay in an abstract class, and subclasses can be customized.

34. What are magic methods in PHP?

Magic methods in PHP are special built-in methods that start with a double underscore ” _ “. Few examples of magic methods are:

  • __construct() – The constructor method that is called automatically when an object is created
  • __destruct() – The destructor method that is invoked when the object is destroyed
  • __get() – Invoked when trying to read a non-accessible property
  • __set() – Automatically called when trying to assign a value to a non-accessible property

Advanced PHP Interview Questions

35. What are the steps to create a new database using MySQL and PHP?

There are four basic steps that are used to create a new MySQL database in PHP. They are as follows:

  • First, a connection is established to the MySQL server using the PHP script.
  • Second, the connection is validated. If the connection is successful, then you can write a sample query to verify.
  • Queries that create the database are input and later stored into a string variable.
  • Then, the created queries are executed one after the other.

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36. How does string concatenation work in PHP?

String concatenation is carried out easily in PHP by making use of the dot(.) operator. Consider the following example:

<!--?php $string1="Welcome"; $string2="to Intellipaat"; echo $string1 . " " . $string2; ?-->

Output: Welcome to Intellipaat

37. Is it possible to set infinite execution time in PHP?

Yes, it is possible to have an infinite execution time in PHP for a script by adding the set_time_limit(0) function to the beginning of a script.

This can also be executed in the  ‘php.ini’  file if not at the beginning of the script.

38. How can we increase the execution time of a PHP script?

  • The default time allowed for a PHP script to execute is 30 seconds as mentioned in the php.ini file. The function used is set_time_limit(int sec). If the value passed is ‘0’, it takes unlimited time. It should be noted that if the default timer is set to 30 seconds and 20 seconds is specified in set_time_limit(), the script will run for 45 seconds.
  • This time can be increased by modifying max_execution_time in seconds. The time must be changed keeping in mind the environment of the server. This is because modifying the execution time will affect all the sites hosted by the server.
  • The script execution time can be increased by:
    • Using the sleep() function in the PHP script
    • Using the set_time_limit() function

The default limit is 30 seconds. The time limit can be set to zero to impose no time limit

To know more about PHP, enroll in our Online PHP Training Course now!

PHP Interview Questions for 7 Years Experience

39. Compare PHP and Java.

Criteria PHP Java
Deployment area Server-side scripting General-purpose programming
Language type Dynamically typed Statically typed
Providing a rich set of APIs No Yes

Check out our Java Tutorial

40. What is Zend Engine?

Zend Engine is used internally by PHP as a compiler and runtime engine. PHP Scripts are loaded into memory and compiled into Zend OPCodes.

These OPCodes are executed and the HTML generated is sent to the client.

The Zend Engine provides memory and resource management and other standard services for the PHP language. Its performance, reliability, and extensibility have played a significant role in PHP’s increasing popularity.

41. What are magic methods?

Magic methods are member functions that are available to all the instances of a class. Magic methods always start with ‘__’, for example, __construct(). All magic methods need to be declared as public.

To use a method, it should be defined within the class or the program scope. Various magic methods used in PHP5 are:

  • __construct()
  • __destruct()
  • __set()
  • __get()
  • __call()
  • __toString()
  • __sleep()
  • __wakeup()
  • __isset()
  • __unset()
  • __autoload()
  • __clone()

42. What is Smarty?

Smarty is a template engine written in PHP. Typically, these templates will include variables—like {$variable}—and a range of logical and loop operators to allow adaptability within the templates.

43. In what different conditions do we use require() vs. include()?

We use require() when the file that is included is essential for your script to work. In other words, if we want our code to immediately stop when the file is not present, we will use require().

We use include() when the file which is included is not mandatory for your script to work. In other words if we want our code to continue execution when the file is not present, we will use include().

44. How to handle file uploads securely in PHP?

When allowing users to upload files to your site, it opens up security risks. Files could contain malicious code or viruses. The goal is to handle the uploads safely. Here are some steps:

  1. Use HTTPS on your site to encrypt traffic.
  2. Check that the uploaded file is less than a max file size you allow, say 10MB.
  3. Ensure the file type being uploaded matches the allowed types you support (for example, JPG, PNG images).
  4. Give each file a random, unique name on the server; don’t rely on the user given filename.
  5. Scan the content before making uploaded files publicly accessible – this checks for viruses.
  6. Store files outside your main web server folder; limit access.

PHP Interview Questions for 10 Years Experience

45. What library is used for PDF in PHP?

The PDF functions in PHP can create PDF files using PDFlib version 6. PDFlib offers an object-oriented API for PHP5 in addition to the function-oriented API for PHP4.
There is also the » Panda module.

FPDF is a PHP class, which allows generating PDF files with pure PHP (without using PDFlib). F from FPDF stands for Free: we may use it for any requirement and modify it to suit our needs. FPDF requires no extension (except zlib to activate compression and GD for GIF support) and works with PHP4 and PHP5.

46. What are the new features introduced in PHP7?

  • Zend Engine 3 performance improvements and 64-bit integer support on Windows
  • Uniform variable syntax
  • AST-based compilation process
  • Added Closure::call()
  • Bitwise shift consistency across platforms
  • (Null coalesce) operator
  • Unicode codepoint escape syntax
  • Return type declarations
  • Scalar type (integer, float, string, and Boolean) declarations

47. What is htaccess? Why do we use it and where?

The .htaccess files are configuration files of Apache Server that provide a way to make configuration changes on a per-directory basis. A file, containing one or more configuration directives, is placed in a particular document directory; the directives apply to that directory and all subdirectories thereof.

These .htaccess files are used to change the functionality and features of the Apache web server.

For instance:

  • The .htaccess file is used for URL rewrite.
  • It is used to make the site password-protected.
  • It can restrict some IP addresses so that on these restricted IP addresses, the site will not open.

48. How can we execute a PHP script using a command line?

We just have to run the PHP CLI (Command-line Interface) program and provide the PHP script file name as the command-line argument, for example, php myScript.php, assuming php as the command to invoke the CLI program.

We have to keep in mind that if our PHP script is written for the Web CGI interface, it may not execute properly in the command-line environment.

If you are looking forward to becoming an expert in Web Development, make sure to check out Intellipaat’s Web Development Online Course. Here, you can learn all of the concepts thoroughly and earn a course certificate as well!

49. Explain REST API development in PHP.

A REST API allows different software systems to communicate with each other over the internet using the HTTP protocol. The API exposes various operations that can be consumed by sending requests and receiving responses.

Building a REST API with PHP involves:

  1. Using a framework that structures code well
  2. Creating PHP functions for key operations like getting, adding, or updating data.
  3. Mapping URL endpoints to those functions – for example, a GET request to /users would trigger getting user data
  4. Serializing data output from PHP into common formats like JSON 
  5. Standardizing error handling, for example, sending back error codes like 400 or 500
  6. Proper documentation and reporting
  7. Performing authentication, that is, using API keys, so that only authorized systems can make requests
  8. Final Hosting is deploying the PHP application with API endpoints accessible over HTTP.

The above-mentioned steps are simplified from an interview point of view.

50. Explain integrating PHP applications with third-party web services.

When building PHP apps, you often need to connect them to existing external services over the internet. For example, payment gateways, shipping APIs, weather data, Google Maps, etc. This is done through integration.

The steps are:

  1. Find web services relevant to enhancing your PHP app’s functionality. 
  2. Register with the provider to get authentication keys to access their API.
  3. The external service exposes endpoints and docs for operations like – getting users, refunding  payments etc.
  4. In your PHP code, use cURL to craft and send API requests to their servers with authentication.
  5. Parse their JSON response back into PHP objects to extract the actual data.
  6. Use the data – for example, to show shipped orders on your site.

The above-mentioned steps are simplified from an interview point of view.

51. How are two objects compared in PHP?

PHP provides you with the ‘==’ operator, which is used to compare two objects at a time. This is used to check if there is a common presence of attributes and values between the objects in comparison.

The ‘===’ operator is also used to compare if both objects in consideration are referencing to the same class.

Next up on these PHP interview questions, you need to understand a fundamental concept.

52. What is NULL in PHP?

NULL is a special data type in PHP used to denote the presence of only one value, NULL. You cannot assign any other value to it.

NULL is not case sensitive in PHP and can be declared in two ways as shown below:

$var = NULL:

Or

$var = null;

Both of the above syntaxes work fine in PHP.

53. How are constants defined in PHP?

Constants can be defined easily in PHP by making use of the define() function. This function is used to define and pull out the values of the constants easily.

Constants, as the name suggests, cannot be changed after being definition. They do not require the PHP syntax of starting with the conventional $ sign.

54. What is the use of the constant() function in PHP?

The constant() function is used to retrieve the values predefined in a constant variable. It is used especially when you do not know the name of the variable.

55. What are the various constants predefined in PHP?

PHP consists of many constants, and the following are some of the more widely used ones:

  • _METHOD_: Represents the class name
  • _CLASS_: Returns the class name
  • _FUNCTION_: Denotes the function name
  • _LINE_: Denotes the working line number
  • _FILE_: Represents the path and the file name

56. Differentiate between variables and constants in PHP.

Variable Constant
Variables can have changed paths Constants cannot be changed
The default scope is the current access scope Constants can be accessed throughout without any scoping rules
The $ assignment is used for definition Constants are defined using the define() function
Compulsory usage of the $ sign at the start No need for the $ sign for constants

To learn more about React JS check out Intellipaat’s React JS Course.

57. Differentiate between static and dynamic websites.

Static Website Dynamic Website
The content cannot be manipulated after the script is executed The content can be changed even at the runtime
No way to change the content as it is predefined The content can be changed easily by manipulation and reloading

58. What are the variable-naming rules you should follow in PHP?

There are two main rules that you have to follow when naming a variable in PHP. They are as follows:

  • Variables can only begin with letters or underscores.
  • Special characters such as +, %, -, &, etc. cannot be used.

59. What is the meaning of break and continue statements in PHP?

Break: This statement is used in a looping construct to terminate the execution of the iteration and to immediately execute the next code snippet outside the scope of the iterating statement.

Continue: This statement is used to skip the current iteration of the loop and continue to execute the next iteration until the looping construct is exited.

60. What is the use of the final class and the final method in PHP?

The ‘final’ keyword, if present in a declaration, denotes that the current method does not support overriding by other classes. This is used when there is a requirement to create an immutable class.

Note: Properties cannot be declared as final. It is only the methods and classes that get to be final.

Next up on this core PHP interview questions and answers blog, let us take a look at the intermediate questions.

61. What are the types of arrays supported by PHP?

There are three main types of arrays that are used in PHP.

  • Indexed arrays: These are arrays that contain numerical data. Data access and storage are linear in indexed arrays.
  • Associative arrays: There are arrays that contain strings for indexing elements.
  • Multidimensional arrays: These are arrays that contain more than one index and dimension.

62. How does the ‘foreach’ loop work in PHP?

The foreach statement is a looping construct used in PHP to iterate and loop through the array data type. The working of foreach is simple; with every single pass of the value, elements get assigned a value and pointers are incremented. This process is repeated until the end of the array.

The following is the syntax for using the foreach statement in PHP:

foreach(array)
{
Code inside the loop;
}

63. What are the data types present in PHP?

PHP supports three types of data handling, and they are as shown in the following table:

Scalar Data Types Compound Data Types Special Data Types
●       Boolean

●       Integer<>

●       Float

●       String

●       Array

●       Object

●       NULL

●       Resource

If you are looking to become proficient in PHP and learn all of the concepts thoroughly, make sure to check out Intellipaat’s PHP Course.

64. How can a text be printed using PHP?

Text can be output onto the working environment using the following methods:

  • Echo
  • Print

The following code denotes the usage of both:

<?php echo "Using echo";
print "Using print"; ?>

65. What is the use of constructors and destructors in PHP?

Constructors are special methods in PHP that are automatically invoked at the time of object creation. Their primary purpose is to initialize the object’s properties and perform any necessary setup tasks. Constructors are particularly useful for ensuring that an object is in a valid and usable state upon instantiation. They allow developers to define and set initial values for the object’s properties or perform other initialization logic. By using constructors, the object can be properly configured and ready to be utilized immediately.

Destructors are automatically invoked when an object goes out of scope. Their primary objective is to execute cleanup operations prior to the object’s destruction and the subsequent release of its memory. Destructors prove valuable in releasing resources, closing database connections, and performing any essential cleanup tasks. Through the implementation of destructors, developers can ensure the proper management and release of resources when they are no longer needed, effectively preventing memory leaks and other potential issues.

66. What are some of the top Content Management Systems (CMS) made using PHP?

There are many CMS that are made using PHP. The popular ones are as mentioned below:

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67. How are comments used in PHP?

There are two ways to use comments in PHP. They are single-line comments and multi-line comments.

Single-line comments can be left using the conventional ‘#’ sign.

Example:

<?php
# This is a comment
echo "Single-line comment";
?>
Multi-line comments can be denoted using ‘/* */’ in PHP.

Example:

<?php
/*
This is
a
Multi-line
Comment
In PHP;
*/
echo "Multi-line comment";
?>

Now to find out the difference between an indexed and an associative array.

Also check out Exception Handling in Python

68. Differentiate between an indexed array and an associative array.

Indexed arrays have elements that contain a numerical index value.

Example: $color=array("red","green","blue");

Here, red is at index 0, green at 1, and blue at 2.

Associative arrays, on the other hand, hold elements with string indices as shown below:

Example: $salary=array("Jacob"=>"20000","John"=>"44000","Josh"=>"60000");

69. Is typecasting supported in PHP?

Yes, typecasting is supported by PHP and can be done very easily. Following are the types that can be cast in PHP:

  • (int), (integer): Cast to integer
  • (bool), (boolean): Cast to boolean
  • (float), (double), (real): Cast to float
  • (string): Cast to string
  • (array): Cast to array
  • (object): Cast to object

70. Does PHP support variable length argument functions?

Yes, PHP supports the use of variable-length argument functions. This simply means that you can pass any number of arguments to a function. The syntax simply involves using three dots before the argument name as shown in the following example:

<?php
function add(...$num) {
$sum = 0;
foreach ($num as $n) {
$sum += $n;
}
return $sum;
}
echo add(5, 6, 7, 8);
?>

Output: 26

71. What is the use of session_start() and session_destroy() functions?

In PHP, the session_start() function is used to start a new session. However, it can also resume an existing session if it is stopped. In this case, the return will be the current session if resumed.

Syntax:

session_start();

The session_destroy() function is mostly used to destroy all of the session variables as shown below:

<?php
session_start();
session_destroy();
?>

72. How can you open a file in PHP?

PHP supports file operations by providing users with a plethora of file-related functions.

In the case of opening a file, the fopen() function is used. This function can open a file or a URL as per requirement. It takes two arguments: $filename and $mode.

Syntax:

resource fopen ( string $filename , string $mode [, bool $use_include_path = false [, resource $context ]] )

73. What is the use of $message and $$message in PHP?

Both $message and $$message are variables in PHP and the difference lies in the name. While $message is a variable with a fixed name, $$message is a variable with a name that is actually stored in $message.

Consider the following example:

If $message consists of ‘var’, then $$message is nothing but ‘$var’.

Next up on these core PHP interview questions, you have to know a very important difference in PHP.

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74. What is the use of lambda functions in PHP?

Being an anonymous function, the lambda function is used to first store data into a variable and then to pass it as arguments for the usage in other methods or functions.

Consider the following example:

$input = array(2, 5, 10);
$output = array_filter($input, function ($x) { return $x > 2; });

The lambda function definition here:

function ($x) { return $x > 2; });

This is used further to store data into a variable, and then you can use it when required without the requirement of defining it again.

Also check out lambda function in Python

75. Differentiate between compile-time exception and runtime exception in PHP.

As the name suggests, if there is an occurrence of any sort of exception while the script is being compiled, it is called a compile-time exception. The FileNotFoundException is a good example of a compile-time exception.

An exception that interrupts the script while running is called a runtime exception. The ArrayIndexOutOfBoundException is an example of a runtime exception.

Also, check our blog on CRUD Operations in PHP using MySQL.

76. What is the meaning of type hinting in PHP?

Type hinting is used in PHP when there is a requirement to explicitly define the data type of an argument when passing it through a function.

When this function is first called, PHP will run a quick check to analyze the presence of all the data types that are specified. If it is different, then the runtime will stop as an exception will be raised.

Next up you have to understand how to connect a URL with PHP.

77. How is a URL connected to PHP?

Any URL can be connected to PHP easily by making use of the library called cURL. This comes as a default library with the standard installation of PHP.

The term ‘cURL’ stands for client-side URL, allowing users to connect to a URL and pick up information from that page to display.

78. What rules are there for determining the

A value is said to be “true” if it is either a non-empty string or a non-zero number. Anything else, such as a null value or an empty string, is regarded as false. Additionally, an array is false if it is open and correct if it has at least one entry. Null is also thought to be incorrect.

To learn full-stack development in detail, sign up for Intellipaat’s Full Stack Developer Online Course and learn from industry experts.

79. Explain how to submit a form without a submit button.

A form can be posted or submitted without the button in the following ways:

  • On the OnClick event of a label in the form, a JavaScript function can be called to submit the form.
    Example:
document.form_name.submit()
  • Using a Hyperlink: On clicking the link, a JavaScript function can be called.

Example:

Q5 php IQA code

  • A form can be submitted in the following ways as well without using the submit button:
    • Submitting a form by clicking a link
    • Submitting a form by selecting an option from the drop-down box with the invocation of an onChange event
    • Using JavaScript:
document.form.submit();
  • Using header(“location:page.php”);

80. What is meant by PEAR in PHP?

PEAR is an acronym for PHP Extension and Application Repository. The purpose of PEAR is to provide:

  • A structured library of open-sourced code for PHP users
  • A system for code distribution and package maintenance
  • A standard style for writing code in PHP
  • PHP Foundation Classes (PFC)
  • PHP Extension Community Library (PECL)
  • A website, mailing lists, and download mirrors to support the PHP/PEAR community

Also check out the blog on forms

81. Explain soundex() and metaphone().

The soundex() function calculates the soundex key of a string. A soundex key is a 4-character long alphanumeric string that represents the English pronunciation of a word. The soundex() function can be used for spelling applications.

<?php 
$str= “hello”;
Echo soundex($str);
?>

The metaphone() function calculates the metaphone key of a string. A metaphone key represents how a string sounds if it is pronounced by an English (native) person. This function can also be used for spelling applications.

php 
echo metaphone(“world”);

82. What is Memcache?

Memcache is a technology that caches objects in memory such that a web application can get to them really fast. It is used by sites, such as Digg, Facebook, and NowPublic, and is widely recognized as an essential ingredient in scaling any LAMP.

PHP Coding Interview Questions

83. Write a program to reverse a string without using built-in functions for php

<!--?php 

function reverseString($str) {
  $reversedStr = ''; 
  $strLen = strlen($str);
  for($i=$strLen-1; $i>=0; $i--){
    $reversedStr .= $str&#91;$i&#93;; 
  }
  return $reversedStr;
}

$input = "Hello World";

$output = reverseString($input);

echo "Reversed String: " . $output;

?-->

84. Find duplicates in an array and return an array with duplicates removed.

<!--?php 
function removeDuplicates($array) {
    return array_unique($array);
}

$inputArray = &#91;1, 2, 3, 4, 5, 2, 3, 6&#93;;
$outputArray = removeDuplicates($inputArray);

print_r($outputArray);
?-->

85. How can we encrypt a password using PHP?

The crypt () function is used to create one-way encryption. It takes one input string and one optional parameter. The function is defined as:

crypt ($input_string, $salt)

Here, $input_string consists of the input string that has to be encrypted and $salt is also a string parameter that is used to generate a strong password and it acts as the base of the hashing process here. PHP uses DES for encryption. The format is as follows:

php code

PHP MCQ Questions with Answers

86. Which of the following is used to get data from forms?

  1. Get
  2. Request
  3. Post
  4. Fetch

Post

87. Which PHP function is used to find files?

  1. filename
  2. file_exist
  3. find
  4. file_exists

file_exists

88. Which function can be used to escape special characters in a string?

  1. esc()
  2. escape()
  3. backslash()
  4. htmlspecialchars()

htmlspecialchars()

89. Which of the following is not a valid PHP variable name?

  1.  $my_Var
  2. $MYVAR
  3. $my var
  4. $myVar_1

$my var

90. Which built-in PHP function returns the length of a string?

  1. length()
  2. sizeof()
  3. strlen()
  4. str_length()

strlen()

Download the PHP Interview Questions and Answers PDF to prepare for interviews offline.

PHP Developer Salary Trends

Job Role  Average   Salary in India Average Salary in the USA
PHP Developer

(0-9 years of experience)

Minimum – ₹49T /mo Minimum – $86T /yr
Average –  ₹88T /mo Average – $92T /yr
Highest –   ₹1L /mo

(estimated)

Highest – $1L /yr

PHP Developer Job Trends

Big giants like Facebook and Zoom even today use PHP for their server-side language. According to the Bureau of Labor Statistics, there will be a 15% growth in web development, including PHP.

  1. Global Trend: Despite the popularity of Python and other fast-growing technologies, the demand for PHP developers is expected to stay strong.
  2. Growth Projections: Many assume that PHP is declining;  however,  around 76.5% of the world’s websites run on PHP. The Bureau of Labor Statistics predicts a 15% rise in jobs related to web development, including PHP roles.

PHP Developer Roles and Responsibilities

Job Opportunities as a Web Developer

According to the job posted on LinkedIn by Ideagen

Role: PHP Developer

Responsibilities 

  • Building full-stack applications for the clients
  • Coordinating with other teams for designs and requirements.
  • Add in data from many different sources and make sure it is accurate.
  • Work concerning SDLC (Software Development Life Cycle) to launch and maintain the product.
  • Be updated with the advancements in the field of tech requirements for development.

Skills Required

  • Should be proficient in PHP
  • Hands-on experience with AWS services like EC2, S3, and RDS
  • For the ETL process, one should have a good understanding of ETL concepts for the integration and migration of the data.
  • Should have a strong hold on the OOPs concept.
  • Familiarity with MVC architecture

Conclusion

We hope this set of PHP Developer Interview Questions will help you prepare for your interviews. Best of luck!

Looking to start your career or even elevate your skills in the field of web development? You can enroll in our PHP, MySQL, HTML, and jQuery Training – Website Development Master’s Program or PHP and MySQL Training and get certified today.

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