Perl - Foreach Loop

The Perl foreach loop is used to loop through each element of a list. In each iteration of the loop, current list element can be accessed using user-defined variable if provided. If the variable is not provided, the current list element can be accessed using topic variable $_.

Syntax

#method 1
foreach variable (list){
  statements;
} 

#method 2
foreach (list){
  statements;
}

Flow Diagram:

Foreach loop over an array

In the example below, the foreach loop is used to access all elements of a given array.

@numbers = (10, 20, 30, 40, 50);  

foreach $i (@numbers) {
  print "i = $i\n";
}

The output of the above code will be:

i = 10
i = 20
i = 30
i = 40
i = 50

Foreach loop over a range

In this example, the foreach loop is used over a range. Elements of the range is accessed using topic variable $_.

foreach (1..5) {
  print "\$_ = $_\n";
}

The output of the above code will be:

$_ = 1
$_ = 2
$_ = 3
$_ = 4
$_ = 5

Foreach loop over a Hash

Consider one more example where the foreach loop is used to access all key/value pairs of a given hash.

%colors = (1 => "Red",
           2 => "Blue",
           3 => "Green",
           4 => "Black",
           5 => "White");

foreach $i (keys %colors) {
  print "$i : $colors{$i} \n";
}

The output of the above code will be:

1 : Red 
2 : Blue 
5 : White 
4 : Black 
3 : Green