On 21.12.2011 07:08, Caligo wrote:
1. The % operator, just like in C/C++, calculates the remainder, but it doesn't handle negative numbers properly. It's not a mod operator, even though sometimes it's called that.assert(-6 % 20 == -6); assert( 6 % -20 == 6); assert(-6 % -20 == -6); I use my own mod function whenever I need to handle negative numbers. It looks like this: pure T mod(T)(T n, T d) if(isIntegral!(T)){ T r = n % d; return sgn(r) == -(sgn(d)) ? r + d : r; } assert(mod(-6, 20) == 14); assert(mod( 6, -20) == -14); assert(mod(-6, -20) == -6); I'm hoping to see something like the above mod function in Phobos someday. And perhapse a 'rem' or 'remainder' function that's a wrapper for the % operator, just to stay consistent. 2. With the above, the math.fmod then would have to be renamed to 'frem' because, just like the % for integrals, it doesn't handle negative numbers properly only calculates the remainder. assert(fmod(-6, 20) == -6); assert(fmod( 6, -20) == 6); assert(fmod(-6, -20) == -6); I'm not so sure why we have 'remainder` and `remquo` in std.math when there is 'fmod`, though. What do you guys think?
Those names and semantics all come from C. We can't change them without an extremely good reason. Note that things are a bit more complicated than you describe -- there is also the IEEE754 remainder function, which is really wierd.
A mod() function might not be a bad idea.
