-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 06/17/2010 07:10 AM, Stewart, Robert wrote:
What about making the difference between two unsigned integers a signed integer?
That sounds like a useful behavior, but if the developer using the library says it should be an unsigned number, I don't think the library should override that.
According to an old C book I have (C: A Reference Manual, 2nd ed, Harbison and Steele), "the result of subtracting one unsigned integer from another is always unsigned and therefore cannot be negative."
Yes, that's the way I've always understood it. I've often taken advantage of that too -- typecasting -1 to an unsigned type gives a value with all bits on, and doesn't require you to know how many bits that type has beforehand. (Yes, there are other ways to do it, like with operator~.)
That may not be definitive, and the C++ standard doesn't dictate the type of the result other than, perhaps, by incorporating the C standard to which I have no access, but it certainly sets expectations that your library ought not violate.
Pretty much what I was thinking. - -- Chad Nelson Oak Circle Software, Inc. * * * -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkwaR3IACgkQp9x9jeZ9/wRuJwCgtAfWrgJyNbq9BH3Sn3Cl/Vpu bO0AoPy4wtImsWECayMJgqmcfcdtWVnm =WIg2 -----END PGP SIGNATURE-----