php interview questions: PHP Interview Questions for 2023 (With Example Answers)


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    php interview questions: PHP Interview Questions for 2023 (With Example Answers)


    For those of us who have been using PHP for a while, it can be hard to believe that there are still developers out there who are just learning the language. But you’d be surprised! If you’re reading this guide, then I’ll assume that you’re one of those new developers—and that’s great! It means we have something in common: an interest in making our lives easier by increasing our knowledge about how to best use the programming language we all love so much.

    What’s the difference between an object and a class?

    The biggest difference between an object and a class is that classes are blueprints for objects.

    Classes are used to define what an object will look like and how it behaves, but they don’t actually create any instances of themselves. You can think of them like recipes: you can read the recipe for lasagna or pizza dough without making any food yourself; however, if you want some real lasagna or pizza dough (i.e., an actual instance), then you need to actually make some by following those recipes with your ingredients and time in the kitchen!

    Objects are instances of their respective classes–they’re tangible things that exist in our world outside of our codebase (like your plate full of delicious homemade lasagna).

    What is the difference between a static and non-static method?

    When you call a method in PHP, you can do so either by instantiating the class or by not instantiating it. If you’re calling a static method, then there’s no need to create an object of your class first–you can just call it directly. Non-static methods require an instance of your class before they can be called.

    Static methods don’t have access to any instance variables within their scope; this means that they cannot access non-static members of the same class without using magic tricks like $this->variable or get_class(). With non-static methods, however (also known as “normal” ones), all is fair game: You can access anything from anywhere!

    What are some of the differences between PHP 5, PHP 7 and PHP 8?

    PHP 5 is the version that most people have been using for years. It’s still being updated, but it doesn’t have many new features.

    PHP 7 was released in late 2015 and has many new features, like anonymous classes and an improved engine with better security and performance.

    PHP 8 was released in late 2018 and has even more improvements than PHP 7 did–for example, you can now use scalar type hints with object references instead of just scalar values like integer and string literals!

    Why use a PDO connection over other options?

    You’re probably familiar with PHP’s PDO library, which stands for “PHP Data Objects.” It’s an object-oriented interface for accessing databases and is part of the Zend Framework.

    PDO provides a consistent API across different database systems (MySQL, PostgreSQL, SQLite, etc.) that makes it easier to switch between different database servers while maintaining your codebase.

    PDO allows you to work with multiple databases in one application by abstracting away all the differences between them into a single API layer–it also means less code needed when switching between different types of databases because they share a common interface

    What is meant by saying that “PHP is an interpreted language”?

    PHP is an interpreted language. This means that the server does not need to compile your code before executing it, as it does with a compiled language like C++ or Java. Instead, the PHP interpreter on your web server will read each line of your script as it downloads from the client’s browser and execute that line immediately.

    Why would you use register_globals off when developing your web apps and websites?

    When developing your apps and websites, it is important to know when to use register_globals. In PHP4, register_globals was turned on by default, but in PHP5 it was turned off by default. Registering variables in the global scope can lead to code injection attacks such as cross-site scripting (XSS) or SQL injections.

    You can turn register_globals on or off using php.ini file as shown below:

    register_globals = Off

    How do you use GetInstanceOf to determine if an object is a specific type of subclassed object in PHP?

    The get_instance_of() function is used to determine if an object is a specific type of subclassed object. It returns true if the object is of the given class, or false otherwise.

    This function can be used in situations where you need to check if a variable contains an instance of a certain class or interface, such as when checking whether an argument passed into your function was defined by its constructor before using it:


    // Example 1 – Checking for instances of a specific class (or interface)

    if ($obj instanceof SomeClass) { … }

    // Example 2 – Checking for instances of multiple classes (or interfaces) at once

    if($obj instanceof ArrayObject AND SomeInterface) {…}

    What does the construct $this mean in PHP?

    The $this variable is used in PHP to reference the current object. It’s like saying “I” or “me” when you’re talking about yourself. For example, if you have a class named Student, you could use $this to refer to an instance of that class:

    The following code shows how we would create a new student object called $student1 and then use $student1 as our current object:

    Note that we don’t need any special syntax for accessing properties or methods on this new student; we simply use dot notation (e.g., $student1::name).

    How can you prevent a script from being accessed by users who have no rights to run scripts on your site?

    To prevent unauthorised access to your script, you can use a .htaccess file. This is a configuration file that can be used with Apache web servers to control access to files and directories on your server.

    A .htaccess file can be used in three ways:

    • Block access to all files and subdirectories under the specified directory (example)
    • Block access to all files and subdirectories under the specified directory except for those explicitly allowed by other directives (example) * Allow access only from specific IP addresses

    How can you change the behaviour of an existing function or class within an existing namespace without destroying anything that applies correctly at present (eg. properties, methods)?

    • Use traits. This is the best way to add functionality to an existing class or function. You can also use inheritance, but be wary of the confusion it might cause for those who are new to PHP and don’t know what’s going on.
    • Use namespaces if you want to keep your code organized and separate from other people’s code (you may not have access).
    • Mix all three together!


    With these questions in mind, we hope you will be able to ace your next PHP interview!

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