Introduction to Perl Interview Questions And Answers
Perl is a general-purpose programming language. Perl is open source language. Perl is originally developed for text manipulation. Perl Interview Questions is used in wide range of applications like:
- System administration
- Web development
- Network programming
- GUI development
A typical simple use of Perl Interview Questions would be for extracting information from a text file and printing out a report or for converting a text file into another form. But Perl provides a large number of tools for quite complicated problems, including systems programming. Programs written in Perl are called Perl scripts, whereas the term the Perl program refers to the system program named Perl for executing Perl scripts.
Part 1 – Perl Interview Questions (Basic)
This first part covers basic Interview Questions and Answers.
1. What is Perl?
PERL stands for Practical Extraction and Reporting Language. Perl is a high-level programming language. Perl is written by Larry Wall. Perl is a powerful free interpreter and it is open source tool.
2. What are the features of Perl programming?
The features of Perl Programming are:
- Perl extracts one of the best features from other languages like C, awk, sed, sh, and BASIC.
- Perl also suits for HTML, XML, and other markup languages.
- Perl supports Unicode
- Perl supports object-oriented programming and procedural language.
- Perl is extensible.
- Perl interpreter can be embedded into other systems.
- Perl having simple syntax and is easier to understand
- Perl is a flexible language
- Perl is easily readable
- Perl database can integrate with other third-party databases such as Oracle, Sybase, Postgres, MySQL, and others.
3. What are the advantages and disadvantages of Perl over C?
Advantages of PERL over C
- Perl runs on all platforms and is far more portable than C
- Perl and a huge collection of Perl Modules are free software
- Perl is very much efficient in TEXT and STRING manipulation
- It is a language that combines the best features from many other languages and is very easy to learn if you approach it properly
- Dynamic memory allocation is very easy in PERL, at any point in time we can increase or decrease the size of the array
Disadvantages of PERL over C
- You cannot easily create a binary image (“exe”) from a Perl file.
- Moreover, if you write a script which uses modules from CPAN, and want to run it on another computer, you need to install all the modules on that other computer, which can be a drag
- Perl is an interpretative language, so it’s comparatively slower to other compiled languages like C
4. What are the scalar data and scalar variables in Perl?
A scalar can contain a single value such as a number or a string. Scalar in Perl means a single entity like a number or string. A scalar data might be an integer number, floating point, a character, a string, a paragraph, or an entire web page.
Variables are the reserved memory locations to store values. This means that when you create a variable you reserve some space in memory. A scalar variable will precede by a dollar sign ($) and it can store either a number, a string, or a reference.
5. What happens when you return a reference to a private variable?
Perl keeps track of your variables when we return a reference to a private variable whether it’s dynamic or otherwise. Perl is not going to free things you are done using them.
6. What is the use of -w, strict and -T functions in Perl?
This command -w gives out warnings if there is a possibility of errors in the script. This command is used to warn about the potential to misinterpret syntax that is located in any Perl script.
A user can invoke a STRICT command to verify the definition and usage of variables within the program. A STRICT command will stop the execution of the script instead of just giving warnings if this command finds any unsafe or ambiguous commands in the script.
The -t command is used for switching taint checking. This command forces Perl to check the origin of variables. This command allows outside variables not to be used in system calls and sub-shell executions.
7. Differentiate USE and REQUIRE in Perl?
- USE method is used for modules while REQUIRE method is used for both modules and libraries.
- The objects which are included are varied at compilation time while in REQUIRE the objects are included are verified at runtime.
- You are not supposed to give a file extension in USE and REQUIRE.
Part 2 – Perl Interview Questions (Advanced)
This first part covers advanced Interview Questions and Answers.
8. How would you ensure the re-use and maximum readability of your Perl code?
Below is the list of points to ensure the re-use and maximum readability of your Perl code:
- Perl offers USE command to modularize code and it includes wherever it is required in a program
- Perl also offers subroutines or functions. This command is used to segregate operations and helps code to be reused
- Perl use objects to create programs and this object will be reused again and again
- Perl include comments in their syntaxes as per requirement
- Perl eliminates dereferencing operator
9. Define a Short Circuit Operator?
The C-style operator will carry out a logical operation which is used to tie logical clauses, the overall value of true is returned if either clause is true. This operator is known as a short-circuit operator because you need not check or evaluate right operand if the left operand is true.
10. How can I eliminate duplicate elements from an array?
Use a hash function to eliminate duplicate elements from an array. Hashes allow you to do some rather interesting manipulations on arrays quickly and efficiently.
11. What are the different functions to add and Remove Elements in Array?
Below is the list of following functions to add/remove and elements:
push(): It adds an element to the end of an array.
pop(): It removes the last element of an array.
unshift(): It adds an element to the beginning of an array.
shift(): It removes the first element of an array.
12. What is the easiest way to download the contents of a URL with Perl?
The easiest way to download the contents of a URL with Perl:
You need to check the libwww-Perl library, LWP.pm installed then you can use below code:
use LWP:: Simple;
$url = get ‘http://rahulanand.com’;
13. What are data types that Perl can handle?
Data types that Perl can handle are:
Scalars ($): It stores a single value.
Arrays (@): It stores a list of scalar values.
Hashes (%): It stores associative arrays which use a key value as an index instead of numerical indexes
14. What Are The Different Types Of Perl Operators?
There are four different types of Perl operators they are
- Unary operator like the not operator
- Binary operator like the addition operator
- Tertiary operator like the conditional operator
- List operator like the print operator
This has been a guide to List Of Perl Interview Questions And Answers so that the candidate can crackdown these Perl Interview Questions easily. You may also look at the following articles to learn more –