Top 20 PHP Interview Questions for 2020

1. What’s the difference between the include() and require () functions?

Both include() and require() function demands a specific file to work on. But on require() function the process exits with a lethal error if the file can’t be included. On the other hand, include() statement passes through and jumps to the next step in the execution.

2. How can we get the IP address of the client?

The$_SERVER["REMOTE_ADDR"]command helps us to get to the IP address of the client.

3. What’s the difference between unset() and unlink()

unset() is used forsetting a variable to “undefined”. On the other hand,unlink()is used to delete a file being passed to it from the file system.

4. How do the main error types in PHP differ?

In PHP, there are several types of errors, each serving different purposes and levels of severity. Here's a breakdown of the main error types

5. What is the difference between GET and POST?

GET requests are used to retrieve data from a server, while POST requests are used to send data to the server to create or update a resource.GET requests are typically used for retrieving data, while POST requests are used for submitting data.

6. How can you enable error reporting in PHP?

First, you need to check if “display_errors” is equal “on” in the php.ini or declare “ini_set('display_errors', 1)” in your script.

After that, include “error_reporting(E_ALL)” in your code to display all types of error messages during the script execution.

7. What are Traits?

Traits are a mechanism that allows you to create reusable code in languages like PHP that does not support multiple inheritances. A Trait cannot be instantiated on its own.

8. Can the value of a constant be changed during the script’s execution?

If the value of a constant is declared, it can’t be changed during the script’s execution.

9. Can you extend a Final defined class?

AFinalclass or method declaration works towards preventing child class or method overriding. Hence it can’t be extended.

10. What are the __construct() and __destruct() methods in a PHP class?

(Question provided byAgli Pançi)

The Constructor method helps in initializing class properties and is called immediately after a new instance of the class is being created.

The Destructor method doesn’t take any parameters.

11. How we can get the number of elements in an array?

Thecount()function helps to return the number of elements in an array.

12. What are the 3 scope levels available in PHP and how would you define them?

The 3 scope levels available in PHP are:

• Private – It is visible only in its own class
• Public – It is visible to any other code accessing the class
• Protected – This one is visible only to classes, parent(s) and classes that extend the current class

13. How can you execute PHP script from the command line?

PHP command can be used in the command line to execute a PHP script. For example, A PHP file named test.php will use the following command to run the script from the command line.

14. What is meant by variable variables in PHP?

If the value of a variable is being used as the name of any other variable, it is called variable variables. We use $$ to declare variable variables in PHP.

15. How many types of arrays are there in PHP?

There are 3 types of arrays in PHP:

• Numeric arrays
• Associative arrays
• Multidimensional arrays.

16. Which function can be used to exit from the script after displaying the error message?

exit() or die() function is used to exit from the current script after displaying the error message.

17. Which function is used in PHP to check the data type of any variable?

You can use gettype() function to check the data type of any variable.

18. How can you increase the maximum execution time of a script in PHP?

To increase the maximum execution time of a script, you have to change the value of the max_execution_time directive in the php.ini file.

19. How can you make a connection with MySQL server using PHP?

To make a connection with MySQL server, you have to provide MySQL hostname, username, and password to make a connection with the MySQL server in mysqli_connect() method or declaring database object of the mysqli class.

20. How can you retrieve data from the MySQL database using PHP?

Answer: Few functions to retrieve the data from the MySQL database using PHP are mentioned below:

• mysqli_fetch_array() –Used to fetch the records as a numeric array or an associative array.
• mysqli_fetch_row() –Used for fetching the records in a numeric array.
• mysqli_fetch_assoc() –Used to fetch the records in an associative array.
• mysqli_fetch_object() –Used to fetch the records as an object.

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