Common PHP Interview Questions With Examples

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Computer programming interviews tend to include common questions used to determine the applicant’s suitability for the position. PHP programmers should prepare for these interview questions in advance to highlight their skills and qualifications for the job. Discover some of the most common PHP interview questions and sample answers in this article.

What are PHP interview questions?

PHP interview questions are common questions posed to PHP job seekers during the application process. Usually, these questions are a combination of basic knowledge questions and problem-solving situations. PHP stands for Hypertext Preprocessor, which is a recursive acronym. It is a computer programming language used for web development and server-side scripting. PHP is a popular language for programmers as it is relatively straightforward to learn as a newcomer but offers advanced programmers challenges.

Why do interviewers ask PHP interview questions?

Interviewers ask specific PHP interview questions to establish the applicant’s skill set, qualifications, and general suitability for the position. PHP can require solving technical issues, so interviewers will often provide problem-solving situations as part of the interview to ascertain the applicant’s ability to apply technical skills to real-world issues.

Common PHP questions to prepare for before an interview

Here are some of the most common questions asked during a PHP interview:

What is PHP, and why is it used?

An interviewer may ask this basic question to establish that you understand the basics of PHP and can clearly explain how it relates to the company’s work. In your answer, you should respond with an example of how PHP can be used specifically for the company for which you are interviewing, if possible.

Example: PHP is an open-source scripting language often used for web development. It can easily be used to code websites for clients as the programmer can use PHP to code, but the client will see it displayed as HTML.

What is the default file extension for PHP?

This is another basic question, but it will demonstrate to the interviewer your understanding of how PHP relates to other computer programs. PHP defaults to .php, but these files can be saved to a variety of extensions. Provide an example of when you might save PHP in some other way.

Example: The default file extension for PHP is .php, but some information is easier to manage as a PDF rather than a PHP file. PHP files can be saved as PDFs pretty easily. Often, you can just navigate to ‘file’ and then ‘print’ and then ‘save as a PDF’ to convert your .php file to a PDF file.

How can we access the client’s IP address?

Interviewers tend to like this question because there are many correct answers. The answer or answers you choose should demonstrate your creativity and an awareness of the practices of the company for which you are interviewing.

Example: There are a few different ways to get the client’s IP address. I would recommend starting by running the command $_SERVER[“REMOTE_ADDR”];.

What is the difference between ‘include’ and ‘require’ in PHP?

Interviewers often use this question in PHP interviews to establish the applicant’s depth of knowledge regarding PHP. A well-explained answer to this question will demonstrate that you know more than just basic definitions regarding PHP but that you can also apply PHP knowledge to problems.

Example: The use of ‘include’ and ‘require’ constructs are extremely similar, but they differ in a major way in execution. If you run ‘include’ and the file cannot be found, then you will receive a warning, but the script will keep running. If you run ‘require’ and the file cannot be found, then you will receive an error, and the script will stop running.

Describe the four main errors in PHP

Error knowledge is valuable for PHP programmers. Understanding the most common errors and why they occur will demonstrate to the interviewer that you are capable of diagnosing problems within PHP and will be able to solve problems that may occur on the job. You might include an example of these errors as they relate specifically to the company for which you are interviewing.

Example: The four main errors in PHP are notice, warning, parse, and fatal. Notice errors are non-critical errors that do not impact the running script. Warning errors are also non-critical. Often, they identify a small error that may become problematic in the future. Parse errors identify missing or incorrect symbols in the code and cause the script to terminate. Fatal errors are critical errors and shut down your whole program.

Describe PHP traits

Traits are a valuable tool in PHP. Understanding and being able to accurately explain how traits function shows the interviewer that you not only possess the necessary knowledge to work with PHP, but you are also a strong communicator and will be able to explain complex technical issues to colleagues or clients.

Example: Traits allow you to group several methods together in order to include them in a class despite the single inheritance structure of PHP. Basically, traits make it easier to code neatly without the excessive duplication that sometimes accompanies single inheritance programming languages.

How does PHP differ from other coding languages?

PHP is a relatively unique coding language with some similarities and many differences from other languages. Interviewers often want applicants to explain how PHP functions in comparison to other languages to demonstrate their general computer science knowledge.

Example: Most computer languages can be sorted into two categories: developing and scripting. PHP can work for both developing and scripting and allows programmers to maximize their time. As it is open-source, it can be applied to many different applications and will not incur the renewal fees that some other languages might require. Overall, PHP is one of the most flexible computer languages for coders.

Is image function supported in PHP?

PHP is often used to add enhancements to websites through various forms and inputs. PHP can also be used to include images with the help of another application. Interviewers like to ask this question to ensure that applicants understand the range of possibilities PHP allows.

Example: PHP can support image function with the assistance of the GD Graphics Library. It supports a variety of file types, including JPEGs, GIFs, and PNGs.

PHP interview tips

Use these PHP interview tips to best prepare for your next interview:

Be creative

Use creativity to solve the problems presented in your interview. Hiring managers will be looking for programmers who can find multiple solutions to one problem.

Stay updated on industry trends

Know the latest updates in the industry. Coding and programming are constantly evolving, so you should stay abreast of any changes that impact PHP.

Solve problems

Prepare to solve complex problems during your interview. Practice problems can be found online to help you get ready for your interview.

Embrace any challenges

Stay positive in the face of challenges. Show the interviewer that you look forward to finding a solution to the problems they present to you.

Use common sense

Some problems will have simple solutions. Give the most logical answer or provide a few different solutions with explanations of their pros and cons.

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