>>182-183
num2 無しにしたらどうよ

class num {
double a;
public:
num(double src) : a(src) { }
operator double() const { return a; }
const num *operator *() const { return this; }
const num operator *(const num *p) const { return pow(a, *p); }
const num operator *(const num &b) const { return a * b; }
};

int main()
{
num a(3.0), b(4.0), x(0), y(0);
double c = a * b; //12
double d = a ** b; //81
x = a * b; //12
y = a ** b; //81
return 0;
}