Hi Zeljko,
On 8/17/08, Zeljko Vrba
On Sat, Aug 16, 2008 at 11:50:05PM +0300, dizzy wrote:
.................................. times in the past by implicit signed -> unsigned conversions in relational comparisons. The most sane thing would be to throw an exception at runtime if one compares a negative integer with some unsigned quantity, instead of getting false for '-1 < 2U', which is a mathematical nonsense. signedness of a type *should not* affect its numerical value in mathematical operations.
I would like to explain explicitly that the int to unsigned int conversion is NOT by accident - it is a "Standard Conversion" and you can find it in Appendix "C" of the book "The C++ Programming Language, 3rd Ed." (TC++PL) by Bjarne Stroustrup. In appendex C of TC++PL, almost all types of conversions are defined, AFAIK. Once you _know_ that it happens then writing something like "-1 < 2U" is entirely your problem to take care of as compiler, IMO, is not likely to issue any warnings because you are explicitly specifying 2 as an unsinged constant by suffixing "U" to it which will automatically convert the -1 to an unsigned bitwise (as a Standard Conversion) because of closeness of the language to the machine which was a huge factor in the language design (you can read Stroustrup's book: "Design and Evolution of C++" to verify that). As you and others have already said earlier, you can always design a new class if you want to make mathematical sense. -Asif