1. Basic Syntax

• Hello World:
  
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  print "Hello, World!\n";
  

• Comments:
  
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  # This is a single-line comment
  

2. Variables

• Scalar Variables: $ for single values
  
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  my $name = "Alice";
  my $age = 30;
  
  

• Array Variables: @ for lists
  
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  my @fruits = ("apple", "banana", "cherry");
  

• Hash Variables: % for key-value pairs
  
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  my %colors = ("red" => "#FF0000", "green" => "#00FF00");
  

3. Control Structures

• • If Statement:
    
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    if ($age > 18) {
        print "Adult\n";
    } elsif ($age == 18) {
        print "Just turned adult\n";
    } else {
        print "Minor\n";
    }
    
    

  • Switch Statement (given as given/when):
    
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    given ($color) {
        when ("red") { print "Color is red\n"; }
        when ("blue") { print "Color is blue\n"; }
        default { print "Unknown color\n"; }
    }
    
    

    Loops:

  • For Loop:
    
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    for (my $i = 0; $i < 5; $i++) {
    print "$i\n";
    }
    

  • Foreach Loop:
    
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    foreach my $fruit (@fruits) {
    print "$fruit\n";
    }
    

  • While Loop:
    
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    my $count = 0;
    while ($count < 5) {
    print "$count\n";
    $count++;
    }
    

4. Subroutines

• Defining and Calling Subroutines:
  
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  sub greet {
  my ($name) = @_;
  print "Hello, $name!\n";
  }greet("Alice");
  

5. File I/O

• Reading from a File:
  
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  open(my $fh, '<', 'file.txt') or die "Cannot open file: $!";
  while (my $line = <$fh>) {
  print $line;
  }
  close($fh);
  

• Writing to a File:
  
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  open(my $fh, '>', 'output.txt') or die "Cannot open file: $!";
  print $fh "Hello, File!\n";
  close($fh);
  

6. Regular Expressions

• Matching:
  
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  if ($string =~ /pattern/) {
  print "Match found!\n";
  }
  

• Substituting:
  
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  $string =~ s/old/new/g; # Replace all occurrences
  

7. Error Handling

• Using eval:
  
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  eval {
  # Code that may fail
  };
  if ($@) {
  print "Error: $@\n";
  }
  

8. Modules and Packages

• Using Modules:
  
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  use strict;
  use warnings;
  use Some::Module;Some::Module::function();
  

• Creating a Module:
  
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  package MyModule;
  
  sub hello {
  return "Hello from MyModule!";
  }
  
  1; # End of module
  

9. Common Built-in Functions

• Length of a String:
  
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  my $length = length($string);
  

• Array Size:
  
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  my $size = @array; # Number of elements in the array
  

• Sorting an Array:
  
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  my @sorted = sort @array;
  

10. Useful Commands

• Run a Perl Script:
  
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  perl script.pl
  

• Check Syntax:
  
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  perl -c script.pl
  

• Install CPAN Modules:
  
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  cpan Module::Name
  

11. Useful Resources

• Official Documentation: Perl Documentation
• Perl Monks: Community support and discussion.
• CPAN: Comprehensive Perl Archive Network for modules.