In this tutorial we will see most commonly asked PHP interview questions.
Most commonly asked PHP interview questions (2023)
Here are some common PHP interview questions and their answers:
Question 1: What is PHP?
Answer: PHP (Hypertext Preprocessor) is a server-side scripting language designed for web development.
Question 2: What is the difference between PHP and HTML?
Answer: HTML is a markup language used for creating web pages but PHP is a scripting language used for creating dynamic web pages.
Question 3: What is the use of echo in PHP?
Answer: The echo statement is used to output text and variables to the screen.
Question 4: What is the difference between double quotes and single quotes in PHP?
Answer: In PHP, single quotes are used to create a string literal but double quotes allow for the embedding of variables and special characters within a string.
Question 5: What is the use of the include() and require() functions in PHP?
Answer: The include() and require() functions are used to include external files in a PHP script. The difference between the two is that require() will cause a fatal error if the file cannot be found, while include() will only generate a warning.
Question 6: What is a session in PHP?
Answer: A session is a way to store information across multiple requests to a PHP script. Session data is stored on the server and is accessible across different pages on the same website.
Question 7: What is the use of the isset() function in PHP?
Answer: The isset() function is used to check whether a variable has been set or not.
Question 8: What is the difference between POST and GET methods in PHP?
Answer: The GET method is used to send data to the server as part of the URL, while the POST method sends data as part of the HTTP request body.
Question 9: What is the use of the header() function in PHP?
Answer: The header() function is used to send a raw HTTP header to the client.
Question 10: What is the difference between abstract interfaces and classes in PHP?
Answer: A class can implement multiple interfaces, but can only inherit from one abstract class. An abstract class can have both abstract and non-abstract methods, while an interface can only have abstract methods.
Question 11: What is the difference between private, protected and public visibility in PHP?
Answer: Private, protected and public are access modifiers used to restrict access to class properties and methods. Private properties and methods can only be accessed within the same class, protected properties and methods can be accessed within the same class and its subclasses, and public properties and methods can be accessed from anywhere.
Question 12: What is a constructor in PHP?
Answer: A constructor is a special method that is called when an object of a class is created. Iinitialize the object with default values is use of this.
Question 13: What is inheritance in PHP?
Answer: Inheritance is a feature of object-oriented programming which allows a class to inherit properties and methods from the another class. The class that inherits from another class is called the subclass, and the class that is inherited from is called the superclass.
Question 14: What is polymorphism in PHP?
Answer: Polymorphism is the ability of objects of different classes to be used interchangeably.Polymorphism is achieved through inheritance and interfaces in PHP.
Question 15: What is the static keyword use in PHP?
Answer: The static keyword is used to define properties and methods that belong to the class rather than to individual objects. Static properties and methods can be accessed without creating an object of the class.
Question 16: What is the final keyword use in PHP?
Answer: The final keyword is used to prevent a class or method from being overridden by a subclass.
Question 17: What is exception handling in PHP?
Answer: Exception handling is a way to handle errors and exceptions that occur during the execution of a PHP script. It allows you to catch and handle errors in a more structured and controlled way.
Question 18: What is a namespace in PHP?
Answer: A namespace is a way to group related classes, functions, and constants together to avoid naming conflicts. It allows you to use the same name for different elements in different namespaces.
Question 19: What is the use of the autoload function in PHP?
Answer: The autoload function is used to automatically load PHP classes when they are needed. It eliminates the need to include class files manually in every script.
Question 20: What is the use of the $_SESSION variable in PHP?
Answer: The $_SESSION variable is used to store session data that can be accessed across different pages on the same website. It is a superglobal variable, which means that it can be accessed from anywhere in a PHP script.
Question 21: What is a closure in PHP?
Answer: A closure is a function that can access variables outside of its scope. It is often used for creating anonymous functions and for passing functions as parameters.
Question 22: What is the use of the use keyword in PHP closures?
Answer: The use keyword is used to pass variables from the parent scope into a closure. This allows the closure to access variables that are not defined within its own scope.
Question 23: What is the difference between array() and  in PHP?
Answer: Both array() and  are used to create arrays in PHP. The difference is that  is a shorthand notation introduced in PHP 5.4, while array() is the traditional way of creating arrays in PHP.
Question 24: What is the use of the array_push() function in PHP?
Answer: The array_push() function is used to add one or more elements to the end of an array.
Question 25: What is the difference between explode() and implode() in PHP?
Answer: The implode() function is used to join array elements into a string, while the explode() function is used to split a string into an array.
Question 26: What is the use of the preg_match() function in PHP?
Answer: The preg_match() function is used to perform a regular expression match on a string. It returns true if the string matches the regular expression, and false otherwise.
Question 27: What is the use of the strip_tags() function in PHP?
Answer: The strip_tags() function is used to remove HTML and PHP tags from a string. This is often used to prevent cross-site scripting (XSS) attacks.
Question 28: What is the use of the file_get_contents() function in PHP?
Answer: The file_get_contents() function is used to read the contents of a file into a string.
Question 29: What is the use of the file_put_contents() function in PHP?
Answer: The file_put_contents() function is used to write a string to a file. It will be created , if the file does not exist.
Question 30: What is the use of the JSON functions in PHP?
Answer: The JSON functions in PHP are used to encode and decode JSON data. JSON is a lightweight data interchange format that is widely used for transmitting data between web servers and clients.