Method which

unittests/catch.hpp:10612–10620

            enum Arch { Big, Little };

            static Arch which() {
                union _{
                    int asInt;
                    char asChar[sizeof (int)];
                } u;

                u.asInt = 1;
                return ( u.asChar[sizeof(int)-1] == 1 ) ? Big : Little;
            }
        };
    }