Factorial in Perl

Published on 28 April 2022 (Updated: 25 September 2022)

Factorial in Perl

Welcome to the Factorial in Perl page! Here, you'll find the source code for this program as well as a description of how the program works.

Current Solution

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

# no input
usage() unless @ARGV == 1;

# accept input as argument
my ($number) = @ARGV;

# if not provided, read from standard input
if (!defined $number) {
	$number = <STDIN>;
	chomp $number;
}

if (!defined $number || $number !~ /^\d+$/ || $number < 0) {
	usage();
}

my $factorial = 1;

for (my $i = 1; $i <= $number; $i++) {
	$factorial = $factorial * $i;
}

print "$factorial\n";

sub usage {
	print "Usage: please input a non-negative integer\n";
	exit;
}

Factorial in Perl was written by:

If you see anything you'd like to change or update, please consider contributing.

Note: The solution shown above is the current solution in the Sample Programs repository as of Oct 16 2019 15:02:04. The solution was first committed on Oct 14 2019 22:44:32. As a result, documentation below may be outdated.

How to Implement the Solution

No 'How to Implement the Solution' section available. Please consider contributing.

How to Run the Solution

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