Hello John, > The % operator is well-defined for unsigned integer numbers. This is news to me, but I've never used C/C++ for any kind of modular arithmetic which would involve negatives. I shall have to be wary if I do :-) > It is > platform dependent when dealing with negatively signed integer numbers. Yikes, that sucks. > Rather depends on if you want Knuth modulus, or Euclidean modulus. Never heard of Knuth modulus, but there again I don't know Knuth's works/ideas much beyond the TeX Book. Also, presumably by Euclidean modulus you mean the Gaussian modulus, such as a = b (mod c) is equivalent to the statement that c|(a-b) (where = is equivalent [i.e. three equal marks] and | means 'divides without remainder'). > int r = abs(n) % abs(d); > return ((n < 0) != (d < 0)) ? ((abs(d)-r)%abs(d)) : r; I see the intention. > There is probably a more efficient way of doing this same thing in > Hacker's Delight by Henry S. Warren > <http://www.amazon.com/dp/0201914654>. I don't have it at my > fingertips right now. Thanks - added to my wishlist - one for a rainy day. > Or you can use the Standard C Library modf() function. So, you're saying modf() will work for signed and unsigned, floating and integer types? Thanks, David.
