c++模板类

#include <iostream>
using namespace std;

template <class T> class A /* T is template type */
{
        public:
                A();
                A(T _a, T _b);
                T sum();
        private:
                T a;
                T b;
};

template <class T> A<T>::A()
{
        a = 0;
        b = 0;
}

template <class T> A<T>::A(T _a, T _b)
{
        a = _a;
        b = _b;
}

template <class T> T A<T>::sum()
{
        return (a + b);
}

int main()
{
        A<int> ai(3, 4);
        A<double> ad(3.1, 4.0);

        cout << ai.sum () << " " << ad.sum () << endl;

        return 0;
}