Top 20 PHP Interview Questions and Answers

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PHP is one of the most popular programming languages used for web development. It is widely used to create dynamic and interactive web applications. If you are preparing for a PHP interview, it is essential to be well-prepared with the common questions and answers that are frequently asked by interviewers.

1. What is PHP?

PHP stands for Hypertext Preprocessor. It is an open-source server-side scripting language that is used to develop dynamic web applications.

2. What are the advantages of using PHP?

PHP offers several advantages, including:

  • Easy to learn and use
  • Platform-independent
  • Supports a wide range of databases
  • Large community support
  • Great documentation

3. What is the difference between include() and require() in PHP?

The include() statement includes and evaluates a specified file, whereas the require() statement includes and evaluates a specified file, but generates a fatal error if the file cannot be found or accessed.

4. What is the difference between GET and POST methods in PHP?

The GET method sends data as a part of the URL, while the POST method sends data as a separate HTTP request. GET is less secure and has a limitation on the amount of data that can be sent, whereas POST is more secure and has no limitation on data size.

5. What is the use of isset() function in PHP?

The isset() function is used to check if a variable is set and not null. It returns true if the variable exists and has a value, and false otherwise.

6. Explain the difference between echo and print in PHP.

Both echo and print are used to output data in PHP. The main difference is that echo can output multiple values at once, while print can only output a single value. Echo is slightly faster than print.

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

The == operator checks if the values of two operands are equal, while the === operator checks if the values and types of two operands are equal.

8. What is a session in PHP?

A session is a way to store information (variables) that can be used across multiple pages. It allows you to store user-specific data and track user activity on a website.

9. How can you prevent SQL injection in PHP?

To prevent SQL injection in PHP, you can use prepared statements or parameterized queries. These methods ensure that user input is properly sanitized and treated as data rather than executable code.

10. What is the difference between htmlentities() and htmlspecialchars()?

The htmlentities() function converts all applicable characters to HTML entities, while the htmlspecialchars() function converts only the predefined HTML entities (<, >, &, “, ‘) to their corresponding entities.

11. What is the use of the header() function in PHP?

The header() function is used to send a raw HTTP header to the browser. It is often used for redirection, setting cookies, and controlling caching.

12. How can you upload files using PHP?

You can upload files using the $_FILES superglobal array and the move_uploaded_file() function. The $_FILES array contains information about the uploaded file, and the move_uploaded_file() function moves the uploaded file to a specified location on the server.

13. What is the use of the explode() function in PHP?

The explode() function is used to split a string into an array based on a specified delimiter. It is commonly used to parse CSV files or separate values in a string.

14. What is the use of the implode() function in PHP?

The implode() function is used to join the elements of an array into a string using a specified delimiter. It is the opposite of the explode() function.

15. How can you handle errors in PHP?

You can handle errors in PHP by using the error_reporting() function to specify which types of errors should be reported, and the error_log() function to log errors to a file. Additionally, you can use try-catch blocks to catch and handle exceptions.

16. What is the use of the unset() function in PHP?

The unset() function is used to unset or destroy a specified variable. It frees up memory by removing the variable and its value from the current scope.

17. What is the use of the count() function in PHP?

The count() function is used to count the number of elements in an array or the properties in an object.

18. How can you connect to a database in PHP?

You can connect to a database in PHP using the mysqli_connect() or PDO (PHP Data Objects) extension. These extensions provide functions and methods to establish a connection, execute queries, and retrieve data from a database.

19. What is the use of the $_SESSION variable in PHP?

The $_SESSION variable is a superglobal variable that is used to store session data. It allows you to store and retrieve data across multiple pages during a user’s session on a website.

20. How can you send email using PHP?

You can send email using the mail() function in PHP. The mail() function takes several parameters, including the recipient’s email address, subject, message, and additional headers.


These are some of the most commonly asked PHP interview questions and their answers. By familiarizing yourself with these questions, you can better prepare for your PHP interview and demonstrate your knowledge and skills in the language. Remember to practice and understand the concepts behind these questions to ace your PHP interview.

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