*** 类模板sample code

#include <iostream>
using namespace std;

template <class T1, class T2>
class Point
{
public:
    Point(T1 x=0, T2 y=0):a(x), b(y){}
    Point(const Point<T1,T2> & x)
    {
        a = x.a;
        b = x.b;
    }
    ~Point(){}
    
    Point<T1,T2> & operator= (const Point<T1,T2> & x)
    {
        a = x.a;
        b = x.b;
        return *this;
    }
    
    Point<T1,T2> operator+ (const Point<T1,T2> & x) //注意返回值不是引用而是值传递
    {
        Point<T1,T2> temp;
        temp.a = a + x.a;
        temp.b = b + x.b;
        return temp;
    }

    T1 a;
    T2 b;
};

template <class T1, class T2>
ostream & operator<< (ostream & out, Point<T1,T2> &x)
{
    out << "(" <<x.a << ", " << x.b << ") " << endl;
    return out;
}
    
int main()
{
    Point<int, double> a1(3, 2.4);
    Point<int,double> b1(2, 1.1);
    Point<int, double> c1;

    c1 = a1 + b1;
    cout << a1 << b1 << c1 << endl;
    
    Point<double, float> a2(1.11, 5.43);
    Point<double, float> b2(11.7,9.2);
    Point<double, float> c2 = a2 + b2;
    
    cout << a2 << b2 << c2 << endl;
    
    return 0;
}

 下面代码展示通过继承方式把模板中与参数无关的代码分离出来

#include <iostream>
using namespace std;

template<class T>
class Base
{
public:
    Base(T x):value(x){}
    virtual void print(void)
    {
        cout << "Base::value = " << value << endl;
    }

    T value;
    int k=0;
};

template<class T, T num>
class Derived: public Base<T>
{
public:
    Derived():Base<T>(num){}
    virtual void print(void)
    {
        cout << "Derived::k = " << this->k << endl;
    }
};

int main()
{
    Derived<int, 1> a;
    Derived<int, 2> b;
    Derived<int, 3> c;
    a.print();
    b.print();
    c.print();
    
    return 0;
}