boost의 static_gcd / static_lcm 흉내내기

Intro

  TMP로 유클리드 호제법을 구현해서 최대공약수와 최소공배수를 컴파일 타임에 얻어보자.

#include <iostream> using namespace std; template <size_t A, size_t B> struct StaticGreatestCommonDivisor { enum { kValue = StaticGreatestCommonDivisor<B, A % B>::kValue }; }; template <size_t A> struct StaticGreatestCommonDivisor<A, 0> { enum { kValue = A }; }; template <size_t A, size_t B> struct StaticLeastCommonMultiplier { private: static const size_t kGCD = StaticGreatestCommonDivisor<A,B>::kValue; static const size_t kA = A/kGCD; static const size_t kB = B/kGCD; public: enum { kValue = kA * kB * kGCD }; }; int main(int argc, char* argv[]) { const size_t kValue = StaticLeastCommonMultiplier<10, 18>::kValue; char array[kValue]{0}; cout << sizeof(array) << endl; return 0; }