Perl last Statement

Summary: in this tutorial, you will learn how to use the Perl last statement to exit a loop immediately.

Introduction to the Perl last statement

The Perl last statement is used inside a loop to exit the loop immediately. The last statement is like the break statement in other languages such as C/C++, and Java.

In practice, you often use the last statement to exit a loop if a condition is satisfied e.g., you find an array element that matches a search key, therefore, it is not necessary to examine other elements.

Because of this, you typically use the last statement in conjunction with a conditional statement such as if or unless .

The following illustrates how to use the last statement inside a while or for loop statement.

Inside a while statement (the same for the until statement):

while(condition){
  # process something
  last if(expression);
  # some more code
}Code language: Perl (perl)

Inside a for loop statement:

for(@a){
   # process current element
   last if(condition);
   # some more code
}Code language: Perl (perl)

For the do while and do until statement, you have to use an additional block {} as described in more detail in the corresponding tutorial.

The following flowchart illustrates how the last statement works inside a while loop statement.

Perl last statement examples

Let’s start with a simple example to find an element in a hash by a given key.

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

my ($key, $value);

my %h = ("apple" => 1,
	 "orange" => 2,
	 "mango" => 3,
	 "coconut" => 4);

print("Please enter a key to search:\n");
$key = <STDIN>;

chomp($key);

$value = 0;

# searching
foreach(keys %h){
    if($_ eq $key){
       $value = $h{$_};
       last;  # stop searching if found
    }
}

# print the result
if($value > 0){
   print("element $key found with value: $value\n");
}else{
   print("element $key not found\n");
}Code language: Perl (perl)

How program works.

• First, we looped over the elements of the hash and compared each hash key with the search key.
• Second, inside the loop, if we found the match, we exited the loop immediately by using the last statement without examining other elements.
• Third, we displayed the result of the search.

Perl last statement with loop label example

If you use the last command alone, it exits only the innermost loop. In case, you have a nested loop that is a loop, called inner loop, nested inside another loop, called outer loop. If you want to exit both the inner and outer loop you need to:

• Put a label in the outer loop.
• Pass the label to the last statement.

The following example demonstrates how to use the last statement with a label:

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

my ($key, $value);

my %h = ("apple" => 1,
	 "orange" => 2,
	 "mango" => 3,
	 "coconut" => 4);

$value = 0;

print("Please enter a key to search:\n");

OUTER: while(<STDIN>){
   # get input form user
   $key = $_;
   chomp($key);

   # seaching
   INNER: foreach(keys %h){
            if($_ eq $key){
		$value = $h{$_};
		last OUTER;  # exit the while loop
            }
   }  # end for
   print("Not found, Please try again:\n") if($value == 0);

}# end while

print("element found with value: $value\n");Code language: Perl (perl)

In this tutorial, we have shown you how to exit the loops immediately by using the Perl last statement.