#!/usr/bin/perl -w
# test.pl --
use strict;
use warnings;
use diagnostics;

my @a = (
'one',
'two',
'three'
);

print join("\n",@a),"\n__________\n";
setmode('add_test',@a);
print join("\n",@a);

sub setmode {
    my $val = shift(@_);
    my @a = @_;
    splice(@a,1,0,$val);
    $_[$_] = $a[$_] for (0..@a);
}

##</code><code>##

C:>test
one
two
three
__________
one
add_test
two

##</code><code>##

sub setmode {
    my($val,$ref) = @_;
    splice(@$ref,1,0,$val);
}