in reply to converting from str to int

You're opening the file wrong. Try this: 
open(FILE, "-|", "bc < res.txt");
@res=<FILE>;
print "@res";

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Re^2: converting from str to int
by Anonymous Monk on Jul 04, 2014 at 21:16 UTC
    bc may be a good hint, but regarding your wording, there's technically nothing wrong with the way the OP is opening the file. The only thing that might be "wrong" with it is that there's no error checking - which your example doesn't do either. e.g. open(FILE, "-|", "bc < res.txt") or die "failed to pipe: $!";
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