PHP Interview Questions for 5 year Experience

Intermediate Level PHP Interview Questions

It's time to go through some of the medium level PHP interview Questions and answers.

11. Describe a few PHP functions.

Ans: Functions are blocks of statements/code that can be used as many times as we want. It increases the code's reusability and makes the code easy to understand.

count - It counts the number of elements in an array or object(countable).

strlen - It is used to get the length of the string.

substr - It is used to get a part of a string.

in_array - It is used to check whether that particular value exists in an array.

is_array - It is used to check whether the given variable is an array.

sprintf - It is used to return a string in a formatting string format.

12. What are the different types of arrays in PHP?

Ans: Three main types of arrays in PHP are:

Indexed array: This type of array contains numeric data.

Associative array: This array contains strings(For indexing elements).

Multidimensional array: This array contains more than one dimension and index.

13. What are the Data types present in PHP?

Ans: There are in total 8 data types in PHP divided into three categories that define the type of data we are specifying.

Integer - Integers are whole numbers without decimal points.

Boolean - Possible values are only true or false.

String - This is a sequence of characters like "Hello"

Double - Double means Floating point numbers like 4.231

Arrays - Arrays are ordered collections of data.

Objects - An instance of a class.

NULL - Supports NULL data.

Resource: Special variables that hold references to external resources to PHP.

14. What is a Session in PHP?

Ans: A computer will know who you are, whether you are opening an application, modifying it, or closing it. This is what a Session does; it stores information across multiple pages and lasts until the user closes the browser. Session variables will store information about only one person and will be available on multiple pages in one application.

Syntax

session_start()

15. What is the use of PHP Constructors and Destructors?

Ans: These two are the essential concepts in the PHP language. Constructors are used to initialize an object's properties, and Destructors are used when an object is destructed or stopped. To create an object from a class, call the __construct() function, and at the end of the script, the __destruct() function in PHP is called automatically.

16. How is the split() function used in PHP?

Ans: The split() function is used in PHP to split the string into different elements. After split() is applied to the string, it returns an array of strings.

17. Which methods are used to print text using PHP?

Ans: A text can be printed or output on the screen using two methods:

Print: The print method has a return value of 1.

Echo: The echo method has no return value.

Example:

<?php echo "Example- echo";

print "Example- print"; ?>

Note: echo method is faster than the print method.

18. Differentiate between the functions strstr() and stristr() in PHP.

Ans: The methods strstr() and stristr() are used to search a string/pattern within another string. The major difference between these two methods is that:

strstr() - case-sensitive

stristr() - case-insensitive

Syntax of strstr() is: 

strstr( $string, $search, $before )

Syntax of stristr() is:

stristr( $string, $search, $before )

19. What are the main types of errors in PHP?

Ans: The three types of errors in PHP are:

Notices

Notices are the non-critical errors that occur during script execution. This error is not visible to users and occurs when a developer includes something wrong in the program.

Warnings

These are more critical than Notice errors. It only warns you that there is an issue and doesn't prevent you from stopping the execution. It occurs when a developer tries to include a missing file.

Fatal

This is the most critical error, which occurred due to an undefined function. It generally occurs when a function is called without having its definition.

20. In PHP, which function is used to delete a file?

Ans: In PHP the unlink() function is used to delete a file. It contains the file's path that needs to be deleted as a parameter.

Syntax

unlink(filename, context)

Advanced Level PHP Interview Questions

Let us take a look at the advanced questions for preparing php interview questions for 5 year experience.

21. What are PHP Magic Functions?

Ans: Magic Functions/methods are methods that are automatically called when certain actions are performed on an object. These functions are unique and are used to create custom functions that allow complex operations. 

All magic functions need to be declared as public.

22. What is the use of Sessions and Cookies in PHP?

Ans: A session is a file or a database that contains data that a server wants to store for each user. In PHP, sessions are always initialized using session_start().

Cookies are small pieces of data that a client's web browser stores when the web server asks. In PHP, the cookie is set using the setcookie() function. Here the data is organized as key/value pairs.

23. What is the difference between PHP's Get and Post methods?

Ans: The difference between Get and Post Methods in PHP is:

24. Differentiate between PHP and Java.

Ans: The difference between PHP and Java language is as follows:

25. What is the purpose of lambda functions in PHP?

Ans: Lambda or anonymous functions are considered shorthand for defining the function that helps write concise code, eliminating extra lines defining a function.

Syntax

$var=function ($arg1, $arg2) { return $val; };

26. What is the use of callback in PHP?

Ans: A callback function in PHP executes the code in response to an event where a function is passed as an argument into another function and ensures that it is only executed when a specific task is completed. There are four types of callbacks in PHP. They are:

• Simple callback.

• Object method callback.

• Callback using a closure.

27. What do you mean by PHP accelerator?

Ans: PHP accelerators are designed to improve the performance of PHP-based web applications. It is a PHP extension that is worked by caching the compiled bytecode(opcode); therefore, it is also referred to as Opcode Caching.

Some of the best PHP accelerators are:

• PHP OPcache 

• Alternative PHP Cache

• Windows Cache Extension for PHP

28. Differentiate between $message and $$message in PHP.

Ans: The main difference between $message and $$message in PHP is that $message is used to store the variable's data, and $$message is used to store the variable's variable. Or we can say that $message is a simple variable and $$message is a reference variable.

For example:

$var = ‘Hello16’

is equivalent to

$size = Hello;
$$size = ‘Hello16’;

$message in PHP is a variable with a fixed name, and $$message is a variable whose name is stored in $message. 

29. What do PHP's encryption functions do?

Ans: Encryption means encoding and decoding of data. In PHP, there are two types of Encryption:

One way Encryption

In One way Encryption, we can only encode the data and cannot decode it. To do this md5() function is used.

Two-way Encryption

In Two way Encryption, we can encode and decode the data, which means both encrypt and decrypt functions are present. The base64_encode() is used to encode the specified data using base64. 

The base64_decode() function is used to decode previously encoded data using base64. 

30. What is the purpose of the imagetypes() method?

Ans: It is an inbuilt function in PHP with no parameters, whose purpose is to return the imagetypes supported by the current version of PHP.

Syntax

int image types( void )

Conclusion

This article discussed the most asked php interview questions for 5 year experience

and their answers. We have covered all the aspects of the PHP language.

Read out more articles on similar topics for further reading:

1. Functions in PHP
2. Data Types in PHP
3. PHP Interview Questions
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5. C# Interview Questions
6. Html interview questions
7. SQL Query Interview Questions
8. MySQL Interview Questions
9. MongoDB Interview Questions
10. Excel Interview Questions
11. MVC Interview Questions
12. Selenium Interview Questions
13. oop interview questions
14. Four Pillars of OOPS

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