...one of the most highly
regarded and expertly designed C++ library projects in the
world.

— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards

**Header: ** <boost/math/common_factor_ct.hpp>

template < unsigned long Value1, unsigned long Value2 > struct boost::math::static_gcd { static unsigned long const value = implementation_defined; }; template < unsigned long Value1, unsigned long Value2 > struct boost::math::static_lcm { static unsigned long const value = implementation_defined; };

The boost::math::static_gcd and boost::math::static_lcm class templates take two value-based template parameters of the unsigned long type and have a single static constant data member, value, of that same type. The value of that member is the greatest common factor or least common multiple, respectively, of the template arguments. A compile-time error will occur if the least common multiple is beyond the range of an unsigned long.

#include <boost/math/common_factor.hpp> #include <algorithm> #include <iterator> int main() { using std::cout; using std::endl; cout << "The GCD and LCM of 6 and 15 are " << boost::math::gcd(6, 15) << " and " << boost::math::lcm(6, 15) << ", respectively." << endl; cout << "The GCD and LCM of 8 and 9 are " << boost::math::static_gcd<8, 9>::value << " and " << boost::math::static_lcm<8, 9>::value << ", respectively." << endl; int a[] = { 4, 5, 6 }, b[] = { 7, 8, 9 }, c[3]; std::transform( a, a + 3, b, c, boost::math::gcd_evaluator<int>() ); std::copy( c, c + 3, std::ostream_iterator<int>(cout, " ") ); }