6 Perl Interview Questions With Sample Answers (Plus Tips)

Updated 27 September 2022

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Perl is an open-source, high-level and stable programming language with cross-platform compatibility and many features borrowed from C and shell scripts. When employers interview candidates for Perl programming positions, they may ask about their experience in using Perl for networking, system administration and various applications involving user interfaces. By understanding the types of questions employers are likely to ask, you can practise answering technical questions and increase your chances of getting a job offer. In this article, we provide Perl interview questions with answers to assist your interview preparation.

6 Perl Interview Questions With Sample Answers

Here are some Perl interview questions that interviewers might ask during a programming interview, along with the sample answers:

1. What are the features of Perl?

The interviewers may begin the interview with this question to assess your basic understanding of the Perl programming language. As a programmer working in Perl, it is essential for you to be familiar with its features. You can answer the question by listing some features of Perl.

Example: 'The Perl programming language has adopted many of its features such as expressions, variables, statements, expressions, subroutines and control structures from C. Its database integration interface can support several third-party databases, making it a versatile option. Perl supports Unicode and complies with Y2K, along with various markup languages. It is also capable of object-oriented, procedural and functional programming.

By using XS or SWIG, you can interface Perl with external C and C++ libraries. You can extend Perl with the various third-party modules available from the Comprehensive Perl Archive Network (CPAN). Perl offers auto-data typing and memory management. The Perl interpreter, which you can embed into other systems, can identify the storage and memory requirements for each data type and can allocate or deallocate memory per usage. It can support complex data structures and has powerful text manipulation utilities and also offers a high level of security.'

2. What are the applications of Perl?

Interviewers ask this question to check your in-depth knowledge of the various applications of the Perl programming language. Knowing these applications is necessary for doing programming work in Perl. You can respond to the question by listing the various applications of Perl that make it popular with programmers.

Example: 'Due to its portability and its ability to customise to an extent between different operating systems, Perl is popular with programmers and has various applications. You can write Common Gateway Interface or CGI scripts with it and use it as a departmental glue to enable smooth interactions between multiple non-homogeneous or non-interoperable systems. Instead of writing entire programmes for systems administration, you can accomplish goals with single commands.

It can process text files and large volumes of data sets, generate SQL queries and analyse strings. Perl is also useful for developing Graphical User Interfaces or GUI, managing cloud data, serving web pages and testing software with the Test Anything Protocol (TAP). In addition, you can use it for speech recognition and text-to-speech translation.'

3. What are the advantages of Perl?

It is an often-asked interview question to assess your understanding of the advantages of working with Perl. Knowing these advantages can help you determine when to use Perl in your programming work. You can answer the question by listing some of the main advantages of the Perl programming language.

Example: 'The main advantages of Perl are that it is open-source, has cross-platform compatibility and is compatible with multiple mark-up languages. You can embed it in web and database servers and extend it with the over 25,000 open-source modules available on the Comprehensive Perl Archive Network (CPAN). It has efficient text manipulation abilities and can handle e-commerce transactions and other encrypted data.'

4. What are the disadvantages of Perl?

Through this question, the interviewer may assess your knowledge of the programming language's drawbacks. In your answer, you can briefly list some disadvantages you may have encountered at work.

Example: 'While Perl is good at scripting, from my experience, it has a lower usability factor than other programming languages and often is unable to manage larger-scale programming. If your code runs over 200 lines, you may face issues. The programmes may run slowly, and every time you make changes to a program, it is necessary to interpret it. As you can use different ways to achieve the same result, you may have an untidy and unreadable code, which can make it difficult to fix the bugs if you do not have extensive programming knowledge.'

5. What are arrays in Perl and how do they differ from lists?

An understanding of arrays is necessary for programming in Perl, so you can expect this question during a job interview. In your answer, you can define an array and explain the purpose of arrays. Follow that by listing the differences between arrays and lists.

Example: 'An array is a type of variable in Perl that can store a list of values. Every object on the list is called an element, and these elements can be a string, a number, another variable or scalar data. An array can only contain scalar elements in Perl. Arrays cannot contain other arrays. To access these ordered lists of scalars, you require a numeric index starting with zero. When writing an array, it is necessary to precede it with an "at" sign.

A list also contains a set of elements, but they differ from an array. A list is immutable, while an array is mutable, which means once you create a list, you cannot directly make changes to it. You can easily make changes to an array and increase or reduce its contents. So, if you want to alter a list, you can do so only after you have stored it as an array.'

6. Can you explain scalar data and scalar variables in Perl?

It is another question that fresher or experienced Perl programmers can expect during a job interview. The purpose of the question is to test your understanding of storing data using scalar variables. In your answer, you can explain what you understand by scalar data and scalar variables in Perl.

Example: 'In Perl, a scalar is a variable that can store different types of scalar data, such as a number, a character, a string, a group of strings, a floating point, a reference or a web page. Scalar variables can represent integers, pointers and other individual fixed-size data objects. You can also use them to stand for one or more primitive type fixed-sized objects or composite type fixed-size objects. Regardless of the data type, a scalar can only store a single data unit at a given time. It uses a "$" sign that precedes one or more alphanumeric characters or an underscore and is case-sensitive.

A scalar data can contain only a single value and serves as the information base you are storing or manipulating with the use of Perl. The two main scalar data types in Perl are string and numeric.'

Perl Interview Preparation Tips

Besides preparing for Perk interview questions, the following tips may help you improve your chances of securing a job:

Research the job. Aside from reading the company's job description, read job descriptions for similar positions with other companies to get a better understanding of the daily job responsibilities that the employer expects you to undertake.
Get informed about the company. You can make a good impression during the interview if you demonstrate familiarity with the company and its products and services. Gather relevant information from the company website, social media platforms, business articles and other online sources.
Review the interview format. Find out about the type of interview you are going to have and prepare accordingly. Ask a family member, friend or colleague to conduct similar mock interviews to help you practise.
Compile a list of questions to ask the interviewer. Asking the right questions can show your interest in the job and let the interviewer know you are sincere about your application.

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