Talk:Even or odd

Silly recursive solution

I made this for Java, but maybe it's not that bad in languages with recursion optimizations: <lang java>public static boolean isEven(int i){ if(i == 0) return true; if(i < 0) i = -i; return !isEven(i - 1); }</lang> --Mwn3d 18:47, 1 December 2011 (UTC)

I'd be quite surprised if anything optimized that very much, as it depends on applying an operation to the result of each recursive call which is usually a sign that the compiler won't be able to figure things out. A human could split that into a pair of functions that are the logical inverse of each other (i.e., isEven and notIsEven) which could then admit optimization, but I suspect that sort of analysis isn't done by compilers (on the grounds that it would so rarely lead to real optimizations in practice). –Donal Fellows 09:48, 2 December 2011 (UTC)