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To me, the key question is whether the signed 0 shows through the interface. I would consider it a mistake if it did so. Besides any "purity" arguments, doing so would eliminate the option of using some otherwise plausible internal representation, such as 2s-complement [...]
Good point. Do you have any references to such packages? I'm curious about the implementation advantages and disadvantages of using 2s-complement vs sign+magnitude.
I tried it with the first large-integer library I developed, many years ago. As I recall, it made addition and subtraction slightly easier to implement, but multiplication and division were slightly harder, as were any more-advanced functions that needed to access the internals of the number (like exponentiation). It was slightly more efficient storage-wise to use 2s-complement, you could just allocate an array instead of having to have a struct *and* an array. (Though if that's all you're after, you could do the same thing with sign+magnitude, if you're willing to engage in some pointer trickery.) It was slightly less efficient for processing, because for anything other than addition and subtraction, you had to remove the sign bit, then calculate, then re-add the sign bit. Overall there wasn't much difference. I prefer sign+magnitude because it's easier to write readable code that way. - -- Chad Nelson Oak Circle Software, Inc. * * * -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAku7lVYACgkQp9x9jeZ9/wRq9QCeNLESN3qXOlHgEhKVFLdhnSn4 Pw4An3SxilFV4IPNaskDGz7HHNZW48P9 =60mH -----END PGP SIGNATURE-----