Perl Tutorial

Fundamentals

Input and Output

Control Flow

Arrays and Lists

Hash

Scalars

Strings

Object Oriented Programming in Perl

Subroutines

Regular Expressions

File Handling

Context Sensitivity

CGI Programming

Misc

Arrays in Perl

Arrays are fundamental structures in Perl that allow you to store ordered lists of scalar values. They are versatile and support a range of operations that make manipulating data straightforward.

Here's a tutorial on arrays in Perl:

1. Defining an Array:

You can define an array in Perl by assigning a list of values to an array variable, which is denoted by the @ symbol.

my @fruits = ("apple", "banana", "cherry", "date");

2. Accessing Array Elements:

Array elements can be accessed using their index, with 0 being the index of the first element.

print $fruits[0]; # prints "apple"
print $fruits[2]; # prints "cherry"

3. Adding Elements to an Array:

push: Add one or more elements to the end of an array.
```
push @fruits, "elderberry";
```
unshift: Add one or more elements to the beginning of an array.
```
unshift @fruits, "apricot";
```

4. Removing Elements from an Array:

pop: Remove and return the last element from the array.
```
my $last_fruit = pop @fruits;
```
shift: Remove and return the first element from the array.
```
my $first_fruit = shift @fruits;
```

5. Array Length:

Find out the number of elements in an array using the scalar context.

my $num_fruits = scalar @fruits;

6. Slicing Arrays:

You can extract a sublist from an array using a slice:

my @sublist = @fruits[1, 2]; # gets ("banana", "cherry")

7. Iterating over an Array:

You can use a foreach loop to iterate over each element:

foreach my $fruit (@fruits) {
    print "$fruit\n";
}

8. Modifying Arrays:

Arrays can be modified directly using their indices:

$fruits[1] = "blueberry";

9. Merging Arrays:

You can combine arrays using the list concatenation:

my @vegetables = ("carrot", "broccoli");
my @food = (@fruits, @vegetables);

10. Special Array Variables:

@_: Default array variable for passed subroutine parameters.
$#array_name: Last index of the array. Useful for accessing the last element or determining the size of an array (size = $#array + 1).

Best Practices:

Use strict and warnings: Always start your Perl scripts with use strict; and use warnings;. This will help catch common mistakes.
Iterate with foreach: It's generally clearer and less error-prone to iterate over arrays with foreach than using a traditional for loop and indices.
Lexical Variables: Use my to declare lexical variables, which are restricted in scope to the enclosed block, rather than global variables.

In conclusion, arrays in Perl offer a dynamic way to handle ordered collections of data. The built-in functions and flexibility provided by Perl make array handling and manipulation both efficient and straightforward.

Creating and initializing arrays in Perl:
- Description: Create and initialize arrays with different elements.
- Code:
```
# Creating and initializing arrays
my @numbers = (1, 2, 3, 4, 5);
my @fruits = qw(Apple Orange Banana);
```

Accessing elements in Perl arrays:

Description: Access individual elements from an array using indices.

Code:

my @colors = ('Red', 'Green', 'Blue');
my $first_color = $colors[0];  # Accessing the first element
print "First color: $first_color\n";

Adding and removing elements from Perl arrays:

Description: Add and remove elements from an array.

Code:

my @names = ('Alice', 'Bob', 'Charlie');

# Adding elements
push @names, 'David';

# Removing elements
pop @names;

Perl array functions and operations:

Description: Utilize various built-in functions and operations on arrays.

Code:

my @numbers = (3, 1, 4, 1, 5, 9, 2);

# Array functions
my $count = scalar @numbers;  # Count elements
my $sum = sum @numbers;       # Sum elements (using List::Util)

# Array operations
my @sorted_numbers = sort @numbers;

Multidimensional arrays in Perl:

Description: Create and work with multidimensional arrays.

Code:

# Creating a 2D array
my @matrix = (
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
);

# Accessing elements
my $value = $matrix[1][2];  # Accessing element at row 1, column 2

Sorting and searching in Perl arrays:

Description: Sort and search elements in an array.

Code:

my @scores = (75, 92, 84, 65, 78);

# Sorting
my @sorted_scores = sort @scores;

# Searching
my $index =  grep { $scores[$_] == 84 } 0..$#scores;

Perl array slices and splicing:

Description: Use array slices and splicing for efficient operations.

Code:

my @colors = ('Red', 'Green', 'Blue', 'Yellow');

# Array slices
my @subset = @colors[1..2];

# Splicing
splice @colors, 1, 2, 'Orange', 'Purple';

Iterating through arrays in Perl:

Description: Iterate through array elements using loops.

Code:

my @days_of_week = qw(Monday Tuesday Wednesday Thursday Friday);

# Using foreach loop
foreach my $day (@days_of_week) {
    print "Day: $day\n";
}

# Using for loop
for my $i (0..$#days_of_week) {
    print "Day $i: $days_of_week[$i]\n";
}

Perl associative arrays (hashes):

Description: Use hashes for key-value pairs, also known as associative arrays.

Code:

# Creating and initializing a hash
my %person = (
    'name' => 'Alice',
    'age' => 30,
    'city' => 'Wonderland'
);

# Accessing values
my $name = $person{'name'};