Multiple ways iterate an array in Perl with an example

Perl arrays are a group of ordered values assigned to a variable. values are scalar types in Perl.

The array can be declared with the @ sign

@numbers = (11, 22, 33,44,55,66);

A single element can be read using an array variable with the dollar($) sign with an index.

print "$numbers[0]\n";

This tutorial explains multiple ways to iterate an array in Perl.

Iterate an array using for loop

• Array is declared and assigned with a list of numbers
• used for loop and do iteration, assign an iterated element to $item
• Print each element using the print statement

Here is an example

@numbers = (11, 22, 33,44,55,66);

for my $item (@numbers) {
  print "$item\n";
}

Output:

11
22
33
44
55
66

Iterate an array with index and element using for loop

• Array is declared and assigned with the list of numbers
• used for loop, Loop values with starting index=0, followed by range operator(..) and end index. The end index can be retrieved with $= array variable. So, Generates sequential index numbers
• Iterate with index variable $i
• Print each element using the print statement, which contains syntax to retrieve an element using index $numbers[$i]

Here is an for loop with index and element example

@numbers = (11, 22, 33,44,55,66);

for my $i (0 .. $#numbers) {
  print "$i - $numbers[$i]\n";
}

Output:

0 - 11
1 - 22
2 - 33
3 - 44
4 - 55
5 - 66

• Loop an array using while and each

These examples are required when you need an index and element for looping an array in Perl. This works in Perl 5.12 version onwards.

• used each with array variable in the while loop
• Each iteration returns an object of index and element
• Print an index and element

Here is an example

@numbers = (11, 22, 33,44,55,66);

while (my ($index, $element) = each @numbers) {
  print "$index - $element\n";

}

Loop elements in an array using a foreach loop

• Array is declared and assigned with a list of numbers
• used foreach loop and do iteration, assign iterated element to $item
• Print each element using the print statement

Here is an example

@numbers = (11, 22, 33,44,55,66);

foreach my $item (@numbers) {
  print "$item\n";
}

Output:

11
22
33
44
55
66

Conclusion

In terms of speed, foreach iteration is faster compared with all other approaches.