Home Interview Questions Top 55 Perl Interview Questions with Answers in 2019

Top 55 Perl Interview Questions with Answers in 2019

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Top 55 Perl Interview Questions with Answers in 2019

Top 55 Perl Interview Questions with Answers: Here are the top interview questions of Perl. Be prepared for the interview. You can download the entire questions in a pdf format. so guys All the best for your interview.

Q1) Compare Perl with C Language.

S.NoPerlC
1There are several development tools in Perl as compare to CDevelopment tools are less and are not very advanced
2It executes in a slower manner than C in a few situationsC has speed almost equal to that of Perl
3Code can be hidden in PerlThe same is not possible in case of C
4Executable can be created without depending on the additional toolsAdditional tools is the prime requirement 

Q2) Can you name the variables in which the chomp works? Also, how they are different from one another?

These are: Scalar and Array

Scalar is generally denoted by symbol $ and it can have a variable which can either be a strong or a number. An array on the other side is denoted by @ symbol. An array is always a number. Both these variables have different namespace. The scalar variables are capable to hold a value of 1 digit while array can have more values. Both of them can be executed in the function whenever there is a need of the same. 

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Q3) Is it possible in the Perl to use code again and again? If so, which feature enable user to that?

Yes, it is possible in Perl. However, there is a limit on usage of the same code in the same program. The users need not to worry about the complexity either as Perl is equipped with a code trimming feature. It automatically guides users on how to keep the code as short as possible. Code reusability is a prime example of this. The feature that enables users to simply keep up the pace towards this is “Inheritance”. The child class in this feature can use the methods of their parent class. 

Q4) How can you represent the warning signs in the Perl in case of an error and what are the options through which this task can be performed?

There is an option in Perl which is known as WCommand Line. All the warning messages can be displayed using this and the pragma function simply makes sure that the user can declare the variables during appearance of warning messages. The entire program can be scrolled easily and in fact, in a very short span of time using the in-built debugger. 

Q5) While writing a program, why the code should be as short as possible?

Complex codes are not always easy to handle. They are not even easy to be reused. Moreover, finding a bug in them is not at all a difficult job. Any software or application if have complex or lengthy code couldn’t work smoothly with the hardware and often have compatibility issues. Generally, they take more time to operate and thus becomes useless or of no preference for most of the users. The short code always makes sure that the project can be made user-friendly and it enables programmers to save a lot of time. 

Q6) What are the advantages and disadvantages of Perl language?

Perl advantages:Its syntax is simple, which makes it easy to understand.It supports OOP concepts.Perl programs run easily on the system.It is more flexible to use.It supports all platforms and is much more portable.It has a rich set of Perl modules and free software.It is much more efficient to work on text and string manipulation as it is a scripting language.Perl combines features of many other languages which make it easy to understand.

Perl disadvantagesA Perl program containing CPAN modules will not run on another system which doesn’t have CPAN modules installed.It is an interpretative language, so it is slower in comparison with other languages.It has untidy and unreadable codes.It starts creating problems when the code is larger than 200 lines.It is not portable.


Q7) Define print() function in Perl?

The Perl print() function prints anything it gets as its argument.


Q8) Define say() function in Perl?

The Perl say() function is not supported by older Perl versions. It is like Perl print() function with only one difference that it automatically adds a new line at the end.


Q9) Define dynamic scoping.

The assignment of temporary values to the global variables is called as dynamic scoping.


Q10) Explain lexical variables.

The variables which are created by the use of ‘my’ operator and private in nature are called as lexical variables.

Q11) Can you add module file in Perl and what are the functions that simply enable you to do so?

Yes, it is possible and there are “Require” “Or” and “Use”

Q12) What are the guidelines about the Perl Modules which a use should pay attention to and follow?

Top 55 Perl Interview Questions with Answers: There are various things that a user should pay attention to. A few important ones are as follow:

1. The user must always make it user that a Package Name should always begin with a capital Letter
2. If there is a file name, the extension for the same could be .pm
3. The package should come from exporter class in case the object is not considered for the same

Q13) For executing a program in Perl, is there any basic condition which the users have to fulfill?

The users must make sure that the program they have accomplished should be passed through the interpreter before its actual execution. It actually compiles the program in a reliable manner and the best part is the users are free to ignore any spaces or marks in the same. 

Q14) How can you say that Perl is compiler?

It is because the interpreter in the Perl is actually free to convert simply the program into the small codes.

(OR)

Is Perl a compiler or Interpreter?

The programming language can also be used both as a compiler and as an interpreter. It takes in the source codes and converts the same into bytecode that is understandable by the programming language. You can then execute and run the program. Therefore, the programming language can both be regarded as an interpreter and a compiler.

Q15) What does CPAN means?

It stands for Comprehensive Perl Archive Network and is a large collection of all the documents and software related to Perl. The programmers can access the same and can avoid the difficulties they face.  CPAN is of significance use for the programmers and they are free to derive a lot of useful information from the same. 

Q16) What does the qq{ } operator do?

The operator encloses a string in the double quotes.


Q17) What does the qx{ } operator do?

The operator encloses a string in the inverted quotes.


Q18) How many data types are there in Perl?

Perl has three data types:

  • Scalars
  • Arrays
  • Hashes

Q19) What are Perl variables?

A variable is a place to store values reserving some memory space. Perl treats the same variables differently based on context.

There are three types of Perl variables:

  • Scalars
  • Arrays
  • Hashes

Q20) What are scalars?

A scalar contains a single unit of data. They are preceded with a ($) sign. A scalar contains a number, character, reference or a string. A reference is the address of the variable.

Q21) What is the significance of the warning messages in Perl and how they are helpful to the users?

These are generally the messages that simply let the user keep an eye on the quality of code. With the appropriate messages, it becomes simple for a user to highlight problems. The user can set the messages as optional while working on the programs. 

Q22) How the information can be inserted into the hashes in Perl?

There is no literal representation in the content of a hash. The users have to make sure that the unwinding of the hash before it is actually filled with the data. The value pairs can be created simply and they can then be converted. In the process of conversion, the hashes can be selected randomly.

(OR)

This hash in this programming language is a group of key-values. These are scalar values. The hashes are used after a % sign and can be created only by assigning a value to it.

For incorporating information in hashes, the key-value pairs should be created which is known as the unwinding of hash. In this case, the even number items are listed on the right called as values, and the ones stored on the left are termed as keys

Q23) Tell one reason why Perl aliases are good enough to be considered and is faster than references?

Top 55 Perl Interview Questions with Answers: They don’t need dereferencing and that is one of the best things about it. A lot of tasks that are not required or are not usual can be avoided easily.

Q24) Tell something about memory management in Perl?

When the programmers make use of a variable in Perl, some memory get occupies. The users have to make sure that the memory is utilized in the best possible manner. After a program is executed, the files can be divided into the sections easily and can then be managed. 

Q25) When you can make use of Perl Grep?

It is basically an important function in Perl that simply let the programmers make sure that the elements that are considered in Perl can be trusted for the long run. It enables programmers to get the elements that are actually suitable with the criteria set by the users on the functions. 

Q26) What is Perl shift array function?

The Perl shift array function removes the leftmost element from the array shortening array by 1.


Q27) What is Perl unshift array function?

The Perl shift array function adds a new element at the start of an array.


Q28) How to replace Perl array elements?

The Perl splice array function removes elements and replaces them with the specified list of elements.


Q29) How to convert strings into an array in Perl?

The Perl split array function splits a string into an array of strings. Thus converting strings into an array.


Q30) How to convert arrays into a string in Perl?

Top 55 Perl Interview Questions with Answers: The Perl join array function combines more than one array into a single string. Thus converting arrays into a string.

Q30) What is Closure in Perl and how it is helpful?

It is defined as the block of code in Perl which is used for capturing the lexical variable which can be accessed at a later section in a program.

Q31) What do you understand by Perl scripting?

It can be regarded as one an important script programming language similar to that of C and C++ language implemented in the IT market. It is mainly used for network operations. The use of Perl scripting depends on the compiler and not on the interpreter. The Perl is used mainly for network operations, developing websites and OS programs.

Q32) Why is Perl scripting used?

Top 55 Perl Interview Questions with Answers: Perl Scripting is used for designing 76 operating systems at the same time and 3000 modules. Other functional concepts can also be done with the help of this programming language. For extending its support to operating systems and modules, it is also known as comprehensive perl archive network modules. In simple words, the use of the language is to extract information from any text file and result in a printing form of the same by converting the text file.

Q33) Explain some advantages and disadvantages of programming using Perl script language?

Advantages – Perl is a high-level programming language that is simpler to understand due to its syntax. It is also easier to use due to its flexibility, and easy readability. In addition, the language also supports OOP. It also becomes easier to understand since it has the ability to combine many languages.

Disadvantages – This software is not portable and has some unreadable codes. It is slower compared to another programming language since it is an interpretative language. When you apply any code which is more than 200 lines, it starts to give in problem within the program. It also contains CPAN module which makes it incompatible to run on the system in which CPAN is not installed.

Q34) What is the importance of Perl warnings and how to turn them on?

Top 55 Perl Interview Questions with Answers: In order to check the quality of any coding in the language, warnings are the basic methods to check the wrong codes. During the lexical analysis stage, some usual mandatory problems are highlighted. Therefore, the time spent for researching weird results are very high which can be minimized by turning on the warnings.

There are several ways to turn on the warnings.

  • -w option is used on the command line for Perl one-liner
  • -w option is also used on shebang line on OS such a UNIX or windows. The Windows Perl interpreter does not require warnings.

For another operating system, the compiler warnings should be selected.

Q35) State the difference between Use and Require?

Both Use and require is used for importing modules and file extension is not required for any of them.

In case of use, the objects included are different at the time of compilation and in case of require, the objects are verified during the runtime.

Q36) What does delete function do in Perl?

To remove a hash element, use delete function. It removes both key and value element from the hash.


Q37) What does undef function in Perl?

The undef function removes the value from the hash, but its key remains there.


Q38) What is the difference between Perl array and Perl hash?

Perl array: They are an ordered list of elements, positioned by index number. It is denoted with @ sign.

Perl hash: They are an unordered list of elements, positioned by their key values. It is denoted with a % sign.


Q39) What is the difference between Perl list and Perl array?

Perl list is a method to organize data in the Perl source code. It is a fixed collection of scalars. They are always one dimensional.

Perl array is a method to store data in the form of variables. They are multi-dimensional.


Q40) What is the difference between use and require in Perl?

Use: It is used only for the Perl modules. The included modules are verified at the time of compilation. It does not need the file extension.

Require: It is used for both Perl modules and libraries. The included objects are verified at runtime. It does need the file extension.

Q41) How many types of primary data structure are there? What do they denote?

There are three types of the primary data structure in this programing language. They are arrays, the scalar, associative arrays.

1. Arrays – It is denoted with ‘@’ sign.
2. Scalar – It is capable of holding one information at one time, and it is denoted by the $ symbol.  Further, this symbol is followed by Perl identifier that can be in the form of underscores or alphanumeric. It should not start with a digit.
3. Associative arrays – These are also called hashes which work similar to that of hash tables used by programmers in other languages.

Q42) How to use a variable in the programming language?

Top 55 Perl Interview Questions with Answers: When you assign a value to a variable with the help of equal sign, a declaration is made. In case of this language, there is no need to declare Perl variable to backup memory space within the application.

Q43) Explain some features of this programming language?

Some features of this programming language are as follows:

1. It is a simple object-oriented programming syntax
2. It helps in designing Unicode
3. It supports 25,000 open modules at the same time
4. It is an open source software and a cross-platform language
5. It also supports databases such as Oracle, MySQL, etc.
6. Vital personal data can be protected with the help of this language such as in e-commerce transactions.
7. It makes use of tools that help in converting a text file into other forms such that it is compatible with HTML or XML.
8. Regular expression engine is offered by the language that is used for changing any type of text file

Q44) Explain the difference between Perl hash and Perl array?

Perl hash is an unordered list of elements where is used by the key values. It is symbolized by a % sign.

Perl array is ordered list of elements used in the programming language which are used by index numbers and symbolized by @ sign.

Q45) How to use modules while working with this language?

A module usually refers to a namespace which is mentioned in a file. Modules are a collection of function, and there are certain guidelines that should be followed while implementing the same in Perl scripting language.

1. The file name assigned should be same as that of the package name.
2  The name of the package should begin with a capital letter.
3. The file names should have ‘pm’ as its extension.
4. The package should be derived from Exporter class in case no object-oriented technique is implemented in the module.
5. For the non-object techniques used in the modules, the functions and variables should be derived from namespace with the help of @EXPORT and @EXPOR_OK arrays.

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Q46) What is the importance of Perl warnings?

Perl warnings help us to check errors in our code by giving warnings.

To enable them use -w :

  1. perl -w scriptName.pl  

Alternatively, you can also supply it within the “shebang” line:

  1. #/usr/local/bin/perl -w  

Q47) Why do we use “use strict” in Perl?

The “use strict” command in Perl calls strict pragma. This pragma helps to catch some bugs or errors in our script and stops the program execution.


Q48) What are Perl strings?

Top 55 Perl Interview Questions with Answers: Strings are an essential part of Perl. They are scalars, so they start with $ sign. Strings can be placed inside single or double quote.

Two types of string operators are there:

  • Concatenation (.)
  • Repetition (x)

Q49) What is an interpolation in Perl?

Interpolation means inserting something with different nature. It can be defined as replacing a variable with its value.


Q50) What is the difference between single (‘) and double (“) quote in a string in Perl?

In the single quote, the value is printed as it is given inside the string without interpolation.

In the double quote, the value is printed with interpolation given inside the string.

Q51) Explain the use of –i, -n, and –p options?

Among all the options, -n and –p is used to include scripts within the loop. The first option is used to enables the programming language implements the script inside the loop. The –p option function in the same manner with addition of continuation. The –i option is used to change the files in the right place. Using this option, the name of the input file can be changed, and the output file would open with the original file name. With this option, no backup of any file is created.

Q52) What does the word subroutine stand for?

It is a block of code used in the above-mentioned programming language which is implemented together in order to task any task. It can be executed at any point in time in any program. To mention some of its advantages, it helps to execute modular programming making it simpler to understand. It also helps to eliminate duplication of any program reusing the same code in the programming language.

53) How to determine strings length in Perl?

String length can be determined with length() function.


54) How to print escaping characters inside a string in Perl?

Escaping characters are the special characters like @, \, /, &, $, “, etc. To print escaping characters put a backslash (\) before escaping characters.


Q55) What is qq (double q)operator in Perl?

The qq operator replaces double quote surrounding a string by its parentheses. You can use qq instead of (“”).

Top 55 Perl Interview Questions with Answers pdf

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