This:

my $gser2= join ';', $gser[0],$gser[1],$gser[2],$gser[3],$gser[4];
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Can be shortened to this:

my $gser2 = join ';', @gser[0..4];
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or even this:

my $gser2 = join ';', @gser;
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Update: Another way is to use the special variable $" to stringify an array:

use strict;
use warnings;

{
    local $"  = q{;};       # locally redefine list separator
    my @gser  = 1..5;
    my $gser2 = "@gser";    # the double quotes force interoplation
    print "gser2 = $gser2\n";
}

__END__
gser2 = 1;2;3;4;5
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