【玩转腾讯云】C++学习笔记-模板

//类模板的写法
template <class T>
class Cml
{
public:
    Cml(T _age = 18, T _weight = 90): age(_age), weight(_weight){}
    T getAge() const {return age;}
    T getWeight() const {return weight;}
    //类模板中成员函数在类内的写法
    Cml& operator+=(const Cml& ss)
    {
        this->age += ss.age;
        this->weight += ss.weight;
        return *this;  
    }
private:
    T age, weight;
};

//成员函数在类外
template <class T>
Cml<T>& Cml<T>::operator+=(const Cml<T>& ss)
{
    this->age += ss.age;
    this->weight += ss.weight;
    return * this;
}

//main函数调用
    Cml<double> cml(80, 160);
    Cml<double> cml1(-70, -50);
    cml += cml1;
    std::cout << cml.getAge() << endl;
    //输出结果是10

template <class T>
class Cml
{
public:
    Cml(T _age = 18, T _weight = 90): age(_age), weight(_weight){}
    T getAge() const {return age;}
    T getWeight() const {return weight;}
    Cml& operator+=(const Cml& ss);
    bool operator <(const Cml& ss) const {return age < ss.age;}//为下列的min函数服务
//    {
//        this->age += ss.age;
//        this->weight += ss.weight;
//        return *this;
//    }
private:
    T age, weight;
};

template <class T>
Cml<T>& Cml<T>::operator+=(const Cml<T>& ss)
{
    this->age += ss.age;
    this->weight += ss.weight;
    return * this;
}

//函数模板
template <class T>//这个T与上面的T表达的意思不一样，名字可以随便起
inline const T& min(const T& a, const T& b)
{
    return b < a ? b : a;
}

//先看main里的调用
    Cml<double> cml(80, 160);
    Cml<double> cml1(-70, -50);
    cml += cml1;
    std::cout << cml.getAge() << endl;
    //以上是类模板，传递的T是double需要在类名后面表明
    //而下面传递的是cml类型，，也就是Cml<double>类型，故而T是不一样的
    //函数模板需要指定类型，编译器会对其进行实参推导，推导出T为Cml<T>故而调用operator<
    Cml<double> a = min(cml, cml1);
    cout << a.getAge() << endl;
    //输出70

template <class T>
class Cml1 : public Cml<T>
{
    template<class T1>
    explicit Cml1(T1 _age, T1 _weight):Cml<T>(_age, _weight){}
};

//在main函数里就可以实现这样一种写法,技术Base是父类，dep是子类
Cml1<Base> ss = new dep(..., ...);//模拟up_cast