the part where i'm stuck is..getting all the numbers between.

use strict;
use warnings;

my $n1 = 1;
my $n2 = 100;
for ($n1 .. $n2) {
    print "$_\n";
}
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Please update your node title: How do I compose an effective node title?

for my $num ($first .. $last) {
    # do something with $num
}
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That for loop will iterate over the numbers in the range, $first to $last.

It sounds like you aren't using a book to learn from. I'd recommend Learning Perl.

You can start with this, then add in the START number and some error checking ...

#!/usr/bin/perl

use strict;

my $end = $ARGV[0] || 1;
my $sum = 0;

for (1..$end) {
    $sum += $_
}

print "Summation = $sum\n";
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... and some example runs ...

{Z} \\vmware-host\Shared Folders > test
Summation = 1

{Z} \\vmware-host\Shared Folders > test 4
Summation = 10
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my $sum = ($n2 + $n1) * ($n2 - $n1 + 1) / 2;
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O(1) for the win. :)





jeffa

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)

(If you're not interested in computer science subtleties, please ignore this node - for normal programming tasks the O(1) estimate is good).

For big numbers the algorithm is slower than O(n), while the summing all the values is O(2^n).

In computer science, if you are talking about O(f(n)), n is the input length, not the number that the input presents.

So adding two numbers with length n is O(n), multiplying two numbers naively is O(n^2), there are a few more elaborate algorithms that do it a bit faster.

Summing all numbers from 1 to $number is O(2^n), because the length of $number is what we call n.

(This calculation kinda assumes use bigint;, because otherwise on the perl vm adding and multiplying is O(1) indeed)

You could do this easily.As others said, you can use range operator to get all the intermediate numbers.If you're getting the start and end numbers from user.You need to check whether the end no is greater than start no.If not, you can't get the range in between them.

my $x = 1;
my $y = 100;

my $sum += $_ for $x..$y;

print $sum;

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use List::Util qw[sum ];<br>
my $totalSum = sum (1..100); 
print "$totalSum\n";
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#!/usr/bin/perl -w

use strict;
use warnings 'all';

my ($n1, $n2) = @ARGV;
die "Usage:\n$0 <n1> <n2>\n"
  unless defined($n1) && defined($n2);
my $total = 0;
map { $total += $_ } $n1..$n2;
print "Total from $n1 to $n2: $total\n";
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