Respected Monks,

Came across this question on LinkeIn for Perl. Someone asked how to find a missing number if in a list of numbers. I came up with following. 

use warnings;
use strict;

my @arr = (19,17,22,23,24,15,16,25..35);


sub find_missing {
        my @stuff = @_;
my @sorted_arr = sort {$a <=> $b} @stuff;

foreach my $num(0..$#sorted_arr-1) {

    my $current = $sorted_arr[$num];
    my $next    = $sorted_arr[++$num];
    my @missing =  ($current+1..$next-1);
    print "$current,";

    if ($next - $current != 1) {
        print "(missing: [@missing]),";
    } 
    
     }

print "$sorted_arr[-1]";
}


&find_missing(@arr);

[download]

The output is shown below: 

C:\>perl findmissing.pl
15,16,17,(missing: [18]),19,(missing: [20 21]),22,23,24,25,26,27,28,29
+,30,31,32,33,34,35

[download]

Is there a better way to write this? I have to do a -1 on the $#sorted_array. I am sure there is a better way, but just dont seem to get it.

On a side node, quite disappointingly, It took me quite a while to write this one. I've started re learning perl and thought I was doing good, till this one came up and shattered my confidence. :) I am glad I figured it out, but it sure took me a long time.

Update:I did several updates to the script so please pardon them.
Thinkpad T430 with Ubuntu 16.04.2 running perl 5.24.1 thanks to plenv!!

In reply to Better way of writing "find the missing number(s)" by pritesh_ugrankar

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