8 PHP Logical Interview Questions With Example Answers

Indeed Editorial Team

Updated 19 March 2023

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PHP is a scripting language that web developers use to create websites and dynamic webpages for various applications. As PHP is a common scripting language that is compatible with various kinds of databases, hiring managers often assess candidates' knowledge of this topic during interviews. Knowing how to answer PHP interview questions can help you distinguish yourself from other candidates and improve your chances of securing employment.

In this article, we provide eight PHP logical interview questions with explanations of why interviewers ask them and example answers for you to study.

8 PHP Logical Interview Questions

Here are eight PHP logical interview questions and example answers:

1. What does PHP mean?

A hiring manager may ask this question to assess your basic familiarity with this scripting language. In your answer, explain what it is and its purpose. You may also state what the acronym 'PHP' previously meant and how it has changed since its inception.

Example: 'PHP once stood for the "Personal Home Page Tools," and one of its very first versions helped its developer, Rasmus Lerdorf, monitor who was viewing his resume online. Today, PHP means "Hypertext Preprocessor." PHP has developed significantly since its inception. Modern developers use it in their web development processes. PHP works with many popular databases, so its use is widespread amongst web developers who work for large and small organisations alike.'

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2. What are the differences between static and dynamic websites?

Individuals who work with PHP create static and dynamic websites, so a hiring manager may enquire about their differences. In your response, you can state how they differ from a developer's and an internet user's perspectives. You may also describe specific use cases so that a hiring manager knows that you understand when to implement each type.

Example: 'Static websites feature content that is the same for every visitor. Each visitor gets an identical experience when they visit a static website. From a developer's perspective, a static website features content that they cannot alter once they run the associated script because all of the content is pre-established. Alternatively, dynamic websites feature unique information that caters to different users' online activities and preferences. The content within a dynamic website can change within the runtime. Search engine results pages are examples of dynamic websites.'

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3. What is the primary difference between PHP4 and PHP5?

A hiring manager may ask this question during an interview to assess your understanding of which PHP version is compatible with the Object-Oriented Programming & System (OOPS) concepts in Java. As a web developer, you may be responsible for working with multiple programming languages, so it is important for you to be able to communicate the differences between PHP4 and PHP 5 compatibility. In your response, explain which version is and which version is not compatible with the OOPS concepts in Java.

Example: 'The main difference between PHP4 and PHP5 is their ability to support the OOPS concepts in Java. PHP4 does not support these concepts, and it uses the Zend Engine 1. PHP4 is no longer active in the web development field, but its use is still relatively popular, so you can still access Zend Engine 1 documentation. PHP5 does support the OOPS concepts in Java, and it uses the Zend Engine 2 that is currently active in the web development industry.'

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4. What are the differences between the 'echo' and 'print' commands in PHP?

Your response to this question can indicate to a hiring manager that you know the key differences between these seemingly related but different commands. In your answer, provide a brief description and discuss their differences, like output values. You may explain that they share statuses as constructs rather than functions.

Example: 'Both "echo" and "print" in PHP are similar in that they are constructs rather than functions. "Echo" does not have a return value, but it can output more than one string. You do not have to use parentheses to add an input, but you can input more than one parameter with the use of parentheses. Unlike "echo," "print" outputs a single string. When you use "print," you do not need to use parentheses. It always produces a return value of 1. Another key difference is that it is much quicker to execute "echo" than it is to execute "print."'

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5. How do you define constants in PHP?

A hiring manager may ask this question to assess if you can create constants that do not change during the script execution. This skill is essential to web development, as it allows you to create components of static web pages. In your response, you can explain constants and offer the two main ways you can define them in PHP.

Example: 'Constants are identifiers or names that do not change during script execution. One of the ways to define a constant is with the define() function. The other way to define a constant is with the const() function.'

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

Arrays are important data structures in PHP that let users amass similar value types within a single value. A hiring manager may ask you to define the different types so that they know you can work with various arrays. In your answer, list the three main types of arrays and state what each array contains.

Example: 'The first type of array in PHP is an indexed array. This array contains a numeric key. The second type of array is the associative array. Within an associative array, you can find each key with its own unique value. The final type of array is the multidimensional array. As its name implies, this type of array holds one or several arrays inside of itself.'

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7. How to produce the length of a string in PHP?

PHP has many functions, and one of them involves acquiring the length of a string. A hiring manager may test your knowledge of this process to learn if you know how to read a string in terms of the number of bytes it has. In your response, provide the function for the number of bytes in a string. You can also provide the function for the number of characters a string contains.

Example: 'The function strlen() produces the number of bytes that a string contains. Knowing the number of bytes in a string can help you determine storage availability and solve related issues. If you prefer to know the string length in terms of the number of characters it has rather than the number of bytes it has, there is a separate function to find this output. You can use the function mb_strlen() rather than strlen() to produce the number of characters within a string.'

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8. What are magic constants in PHP?

Your response to the question can help a hiring manager determine your understanding of the types of constants that challenge the traditional definition. When you know magic constants, you can be a more versatile user of PHP. In your response, you can briefly state their definition and provide the notation that indicates that one is present in your script.

Example: 'A magic constant is a pre-established constant that can change depending on its use in your script. There are nine main magic constants, and they resolve themselves at compile time. This characteristic makes them different from regular constants that resolve themselves at runtime. All magic constants are case insensitive and begin and end with double underscores.'

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