Capgemini Perl Technical Interview Questions and Answers

Perl (Practical Extraction and Report Language) remains a powerful scripting language, widely used in automation, text processing, system administration, and backend scripting. If you’re preparing for a Capgemini technical interview that involves Perl, you can expect both theoretical questions and hands-on coding challenges.

Below, I’ve compiled a set of frequently asked Perl interview questions with answers, covering basic, intermediate, and advanced levels.

1. Basic Perl Interview Questions

Q1. What is Perl?
Perl is a high-level, general-purpose scripting language known for its text-processing capabilities. It’s widely used in system administration, CGI scripting, network programming, and database interaction.

Q2. What are the main features of Perl?

• Strong text and regular expression handling

• Portable and cross-platform

• Rich CPAN (Comprehensive Perl Archive Network) library

• Supports both procedural and object-oriented programming

• Rapid development for automation scripts

Q3. What is the difference between my, local, and our in Perl?

• my – Declares a lexical (scoped) variable, available only within its block.

• local – Temporarily backs up and replaces a global variable within a block.

• our – Declares a package global variable accessible across the package.

Q4. How do you comment in Perl?

• Single-line comment: # This is a comment

• Multi-line: Use POD (Plain Old Documentation) format with =begin and =cut.

Q5. What are scalar, array, and hash variables in Perl?

• Scalar ($) – Stores a single value. Example: $x = 10;

• Array (@) – Stores an ordered list. Example: @arr = (1, 2, 3);

• Hash (%) – Stores key-value pairs. Example: %hash = ('name' => 'John', 'age' => 30);

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2. Intermediate Perl Interview Questions

Q6. What are Perl’s data types?

• Scalars – Numbers, strings

• Arrays – Ordered list of scalars

• Hashes – Key-value mappings

• References – Pointers to arrays, hashes, or functions

Q7. How are regular expressions used in Perl?
Perl is famous for its regex support. Example:

if ($text =~ /Perl/) {
   print "Found Perl!";
}

Here, =~ checks if $text contains the word "Perl".

Q8. How do you read input from the user in Perl?

print "Enter your name: ";
my $name = <STDIN>;
chomp($name);  # Removes newline
print "Hello $name\n";

Q9. What is the difference between use, require, and do in Perl?

• use – Loads modules at compile time.

• require – Loads files at runtime, used mainly for libraries.

• do – Executes a file as a Perl script.

Q10. How do you connect Perl to a database?
Using DBI module:

use DBI;
my $dbh = DBI->connect("DBI:mysql:database=test;host=localhost","user","password");

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3. Advanced Perl Interview Questions

Q11. What is context in Perl?
Perl evaluates expressions based on context:

• Scalar context – Returns a single value.

• List context – Returns a list of values.
  Example:

my @arr = (1,2,3);
print scalar @arr; # prints 3

Q12. What are Perl references?
References act as pointers to variables, arrays, or hashes. Example:

my @arr = (1, 2, 3);
my $ref = \@arr; 
print $ref->[0]; # prints 1

Q13. What is CPAN in Perl?
CPAN (Comprehensive Perl Archive Network) is a large collection of Perl modules contributed by the community. It allows developers to easily install and use prebuilt libraries.

Q14. How do you handle exceptions in Perl?
Using eval block:

eval {
   die "Something went wrong!";
};
if ($@) {
   print "Error: $@";
}

Q15. Explain object-oriented programming (OOP) in Perl.

• Perl does not have built-in OOP syntax like Java or C#, but uses packages and bless function.

• Example:

package Student;
sub new {
   my $class = shift;
   my $self = { name => shift };
   bless $self, $class;
   return $self;
}
sub getName {
   my $self = shift;
   return $self->{name};
}
1;

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4. Real-Time Perl Scenario-Based Questions

Q16. How do you process a large log file efficiently in Perl?

• Use filehandles with while(<FH>) instead of reading whole file at once.

• Apply regex filters for line-by-line matching.

Q17. How do you pass command-line arguments to a Perl script?
Arguments are stored in the @ARGV array. Example:

print "First argument: $ARGV[0]\n";

Q18. How do you find duplicate entries in an array using Perl?

my @arr = (1,2,2,3,4,4);
my %seen;
foreach my $i (@arr) { $seen{$i}++ }
foreach my $k (keys %seen) {
   print "$k is duplicate\n" if $seen{$k} > 1;
}

Q19. How do you handle file operations in Perl?

open(my $fh, "<", "file.txt") or die "Can't open file: $!";
while (my $line = <$fh>) {
   print $line;
}
close $fh;

Q20. What’s the difference between Perl and Python?

• Perl is stronger in regex and text processing, Python is better for general-purpose scripting.

• Perl uses sigils ($, @, %) for variables, Python does not.

• Python is more readable, Perl is more flexible but sometimes cryptic.

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Final Thoughts

At Capgemini Perl interviews, you can expect:

• Questions on regex, arrays, hashes, and file handling

• Hands-on coding for automation tasks

• Real-world problem-solving involving text parsing and database connectivity

If you master Perl fundamentals, advanced concepts, and best practices, you’ll have a strong edge in clearing the interview.