If your list is a scalar then the previous replies will work excellently, if you mean 'list' as an array reference, i.e.: my ($temp) = [121, 122, 123, 124, 125, etc...] you could use

foreach $id (@$temp) {
# do things with $id
}
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or if you wanted a different way, you could assign it to a hash:

@hash{@$temp}=@$t;
foreach $id (keys %hash) {
# do things with $id
}
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with this method you can use the hash to determine if your id exists using the id itself, e.g.

if ($hash{120}) {
# id 120 exists
}
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TMTOWTDI!

--
hiseldl