This is either "picky" or "iggerant" but the statement (above) that...

"You can also add elements anywhere in the array by just storing something at the new index."

... seems to me to be, at once, true, and "possibly confusing."

In short, I don't know any function that will add an element to an array at any arbitrary index nor any technique (aside from the one below) for doing so.

#!usr/perl/bin
use strict;
use warnings;
use Data::Dumper;

my $file0 = "foo.txt";
my $file1 = "bar.txt";
my $file2 = "blivitz.txt";

my @array1 = ($file0, $file1, $file2);

print "Initial array:\n";
my $elementindex = 0;
for my $file(@array1) {
    print "\$elementindex $elementindex is $file\n";
    $elementindex++;
}
print "\n";

# Now adding an interior element to the array, in this case, arbitrari
+ly inserting "new element" 
# after "foo.txt" and before "bar.txt"
#(to add to beginning or end, see push and unshift)

my @temp_array = @array1;    # copy all elements to new array

@temp_array = ($array1[0], "new element", $array1[1], $array1[2]); 

@array1 = @temp_array;         # copy revisions back to @array1

$elementindex = 0;
for my $file(@array1) {
    print "After revisions, \$elementindex $elementindex is $file\n";
    $elementindex++;
}

print "\n";

# This REPLACES the latest content of $array1[1], "new element", with 
+$addelement.txt
# BUT  note it's NOT "add"(ing) an element "anywhere"

my $addelement = "addelement.txt";

$array1[1] = $addelement;   #

$elementindex = 0;
for my $file(@array1) {
    print "now \$elementindex $elementindex is $file\n";
    $elementindex++;
}
[download]

Output:

$elementindex 0 is foo.txt
$elementindex 1 is bar.txt
$elementindex 2 is blivitz.txt

After revisions, $elementindex 0 is foo.txt
After revisions, $elementindex 1 is new element
After revisions, $elementindex 2 is bar.txt
After revisions, $elementindex 3 is blivitz.txt

now $elementindex 0 is foo.txt
now $elementindex 1 is addelement.txt
now $elementindex 2 is bar.txt
now $elementindex 3 is blivitz.txt
[download]

Perhaps splice() ( perldoc -f splice ) is also an option but thus far /me does not see how to implement it.

Perhaps I was less than careful with my use of the word "add". I simply meant you can do this:

my @arr;
$arr[78] = "foo";
[download]

But it is actually pretty straightforward to insert elements into an array, shifting all later elements, using splice:

my @a = ('foo','baz');
splice(@a,1,0,'bar');
print "@a\n";
[download]


--
sgifford's Web page

++, sgifford and many thanks!

And, note the clarity (and, in this case, the particularity and relevance) of sgifford's explanation, as contrasted with

perldoc -f splice
 splice ARRAY,OFFSET,LENGTH,LIST
 splice ARRAY,OFFSET,LENGTH
 splice ARRAY,OFFSET
 splice ARRAY
         Removes the elements designated by OFFSET and LENGTH from an
         array, and replaces them with the elements of LIST, if any. I
+n
         list context, returns the elements removed from the array. In
         scalar context, returns the last element removed, or "undef" 
+if
         no elements are removed. The array grows or shrinks as
         necessary. If OFFSET is negative then it starts that far from
         the end of the array. If LENGTH is omitted, removes everythin
+g
         from OFFSET onward. If LENGTH is negative, removes the elemen
+ts
         from OFFSET onward except for -LENGTH elements at the end of 
+the
         array. If both OFFSET and LENGTH are omitted, removes
         everything. If OFFSET is past the end of the array, perl issu
+es
         a warning, and splices at the end of the array.

         The following equivalences hold (assuming "$[ == 0 and $#a >=
         $i" )

             push(@a,$x,$y)      splice(@a,@a,0,$x,$y)
             pop(@a)             splice(@a,-1)
             shift(@a)           splice(@a,0,1)
             unshift(@a,$x,$y)   splice(@a,0,0,$x,$y)
             $a[$i] = $y         splice(@a,$i,1,$y)

         Example, assuming array lengths are passed before arrays:

             sub aeq {   # compare two list values
                 my(@a) = splice(@_,0,shift);
                 my(@b) = splice(@_,0,shift);
                 return 0 unless @a == @b;       # same len?
                 while (@a) {
                     return 0 if pop(@a) ne pop(@b);
                 }
                 return 1;
             }
             if (&aeq($len,@foo[1..$len],0+@bar,@bar)) { ... }
[download]

For me (and for others?) the first sentence, Removes the elements designated by OFFSET and LENGTH from an array, and replaces... certainly does nothing to suggest that splice provides this elegant alternative to the overhead and verbosity of my lines 24..28 (above). Again, ++!