第十三章——模板

1.模板使类的成员为一个可变的参数

template <模板的形式参数表>
class类名 {...}

#include <iostream>

using namespace std;



    template<class T>
    class Array {

    int low;
    int high;
    T *storage;

public:
    Array(int lh=0,int rh=0):low(lh),high(rh)
    {
        storage=new T[high-low+1];//
    }

    Array(const Array &arr);

    Array &operator=(const Array &a);

    T &operator[](int index);

    ~Array(){if(storage) delete []storage;}

    };





template <class T>
Array<T>::Array(const Array<T> &arr)//不指明返回值类型
{
    low=arr.low;
    high=arr.high;
    storage=new T[high-low+1];
    for(int i=0;i<high-low+1;i++)
        storage[i]=arr.storage[i];
}

template <class T>
Array<T> &Array<T>::operator=(const Array &other)
{
    if(this==&other) return *this;
    delete []storage;
    low=other.low;
    high=other.high;
    storage=new T[high-low+1];
    for(int i=0;i<high-low+1;i++)
        storage[i]=other.storage[i];

    return *this;


}

template <class T>
   T &Array<T>::operator[](int index)
   {
       if(index<low||index>high)
       {
           cout<<"下标越界";
       }
       return storage[index-low];


   }



   int main()
   {
       Array<int> array1(20,30);//类模板的实例化Array<int>
       for(int i=20;i<30;i++)
        cout<<array1[i]<<endl;

   }

//模板类
#include<iostream>
using namespace std;
template <class T>
class B
{
private:
    T x;
public:
    T f(T x) {return x;}
};

int main()
{
  B<char> b;
  cout<<b.f('c');
}

3.类模板的定义和实现都应在.h文件