Perl Programming Language Cheatsheet

Perl, Practical Extraction and Reporting Language, is a versatile and powerful programming language known for its text processing capabilities. Initially developed by Larry Wall in 1987, Perl has evolved into a robust language used in various domains, including system administration, web development, and bioinformatics. This cheat sheet aims to provide a quick reference for Perl programmers, highlighting essential syntax and features.

Hello World in Perl

#!/usr/bin/perl
use strict;
use warnings;

print "Hello, World!\n";

Variables and Data Types

# Scalar variables
my $scalar_var = "Perl";

# Arrays
my @array = (1, 2, 3);

# Hashes
my %hash = ('key1' => 'value1', 'key2' => 'value2');

# Special variable: $_
while (<>) {
    print if /pattern/;
}

Control Structures

# If statement
if ($condition) {
    # code block
} elsif ($another_condition) {
    # code block
} else {
    # code block
}

# For loop
for my $i (1..10) {
    # code block
}

# While loop
while ($condition) {
    # code block
}

# Switch statement (using given-when)
given ($variable) {
    when ($value1) { # code block }
    when ($value2) { # code block }
    default { # code block }
}

Subroutines

sub greet {
    my ($name) = @_;
    print "Hello, $name!\n";
}

greet("Perl");

Regular Expressions

# Matching
if ($string =~ /pattern/) {
    # code block
}

# Substitution
$string =~ s/old/new/;

# Global substitution
$string =~ s/old/new/g;

# Capture groups
if ($string =~ /(pattern1)(pattern2)/) {
    my $group1 = $1;
    my $group2 = $2;
}

File Handling

# Open a file for reading
open my $file_handle, '<', 'filename.txt' or die $!;

# Read from a file
while (<$file_handle>) {
    # code block
}

# Close the file
close $file_handle;

Modules and Packages

# Using a module
use Module::Name;

# Import specific functions
use Module::Name qw(function1 function2);

# Creating a package
package MyPackage;

sub my_subroutine {
    # code block
}

1;  # Required to indicate a successful module

Error Handling

# Die function
open my $file_handle, '<', 'filename.txt' or die $!;

# Eval block
eval {
    # code block
};

if ($@) {
    # handle error
}

Object-Oriented Programming (OO)

# Define a class
package MyClass;

sub new {
    my $class = shift;
    my $self = {};
    bless $self, $class;
    return $self;
}

# Create an object
my $object = MyClass->new();

This cheat sheet covers the basics of Perl programming, providing a quick reference for both beginners and experienced developers. Remember that Perl’s strength lies in its text processing capabilities and flexibility, making it a valuable tool for a wide range of applications. Explore the extensive Perl documentation for more in-depth information and advanced features. Happy coding in Perl!

This cheat sheet provides a basic overview of some essential features in Perl. Refer to the official Perl documentation for more in-depth information and advanced topics.