my @dirs = ('/path/to/dir1', '/some/other/path/to/dir2', '/dir3');
for my $dir (@dirs) {
    ...
}

##</code><code>##

my @dirs = map { sprintf 'abc_%03d', $_ } 1 .. 100;

##</code><code>##

for my $i (0 .. $#dirs) {
    my $dir = $dirs[$i];
    ...
}