You could use splice and reverse to modify @a in place.

use strict;
use warnings;

my @a = qw{ 0 1 5 7 9 5 3 };
my @b = qw{ a b c y e f z a a };

die qq{Element count mismatch\n}
   unless scalar @b == scalar @a + grep m{[yz]}, @b;

print qq{@a\n@b\n};

my $offA = $#a;
foreach my $offB ( reverse 0 .. $#b )
{
    if( $b[ $offB ] =~ m{[yz]} )
    {
        splice @a, $offA + 1, 0, q{I};
    }
    else
    {
        $offA --;
    }
}

print qq{@a\n};

[download]

The output.

0 1 5 7 9 5 3
a b c y e f z a a
0 1 5 I 7 9 I 5 3

[download]

I hope this is of interest.

Cheers,

JohnGG

In reply to Re: add elements to array at certain positions by johngg
in thread add elements to array at certain positions by coldy

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