Hi All,

Task
I am passing a array as a reference to a subroutine which does some checking and returns a scalar.

Method1: 
my $variable = my_subroutine(\@my_array);
sub my_subroutine
{
    my $array = shift;
    # involves dereferencing the array_reference
    ...
    
    return(\$variable);
}

[download]
I get the expected output. Array dereferencing can be quite expensive and I wanted to refine the code further.

Method2:
I thought that I can gain some speed by passing just the array indices and access the array defined outside the subroutine as a global array. Again, I get the expected result. 
my $variable = my_subroutine(\$array_start_idx, \$array_end_idx);
sub my_subroutine
{
    my $start_idx = shift;
    my $end_idx = shift;
    # involves accessong the global array using the indices passed
    ...
    
    return(\$variable);
}

[download]
Problem
When I use Devel-NYTProf to profile both methods, passing the whole array as an array reference is much faster than passing the array indices. I was expecting the opposite of this!
I have to emphasize that innards of the subroutine is dereferencing an array reference in the first option and accessing the global array using the array indices passed to the subroutine.
Any insight into this is greatly apppreciated!

In reply to Pass an array reference or array indices to a subroutine? by umasuresh

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