Default Arguments

A subroutine can fill in a missing argument with a default value.

default_arguments.pl

use strict;
use warnings;

sub count_label {
    my ($count, $noun) = @_;
    $noun //= "item";
    my $label = $count == 1 ? $noun : $noun . "s";
    return "$count $label";
}

my $count = ;
my $text = count_label($count);

print "count=$count\n";
print "text=$text\n";

use strict;
use warnings;

sub count_label {
    my ($count, $noun) = @_;
    $noun //= "item";
    my $label = $count == 1 ? $noun : $noun . "s";
    return "$count $label";
}

my $count = ;
my $text = count_label($count);

print "count=$count\n";
print "text=$text\n";

use strict;
use warnings;

sub count_label {
    my ($count, $noun) = @_;
    $noun //= "item";
    my $label = $count == 1 ? $noun : $noun . "s";
    return "$count $label";
}

my $count = ;
my $text = count_label($count);

print "count=$count\n";
print "text=$text\n";

default argument A default argument supplies a fallback when the caller omits a value.