C++下标运算符详解

返回值类型 & operator[ ] (参数);

    #include <iostream>
    using namespace std;
    class Array{
    public:
        Array(int length = 0);
        ~Array();
    public:
        int & operator[](int i);
        const int & operator[](int i) const;
    public:
        int length() const { return m_length; }
        void display() const;
    private:
        int m_length;  //数组长度
        int *m_p;  //指向数组内存的指针
    };
    Array::Array(int length): m_length(length){
        if(length == 0){
            m_p = NULL;
        }else{
            m_p = new int[length];
        }
    }
    Array::~Array(){
        delete[] m_p;
    }
    int& Array::operator[](int i){
        return m_p[i];
    }
    const int & Array::operator[](int i) const{
        return m_p[i];
    }
    void Array::display() const{
        for(int i = 0; i < m_length; i++){
            if(i == m_length - 1){
                cout<<m_p[i]<<endl;
            }else{
                cout<<m_p[i]<<", ";
            }
        }
    }
    int main(){
        int n;
        cin>>n;
        Array A(n);
        for(int i = 0, len = A.length(); i < len; i++){
            A[i] = i * 5;
        }
        A.display();
        const Array B(n);
        cout<<B[n-1]<<endl;  //访问最后一个元素
        return 0;
    }