下标运算符重载

重载该运算符用于增强操作C++数组的功能。

/***
subscript.cpp
***/
#include<iostream>
using namespace std;
const int SIZE = 10;

class safearay
{
    private:
        int arr[SIZE];
    public:
        safearay()
        {
            register int i;
            for(i = 0; i < SIZE ;i++)
            {
                arr[i] = i;
            }   
        }
        int& operator[](int i)
        {
            if(i > SIZE)
            {
                cout << "the index is too big" << endl;
                return arr[0];
            }
            return arr[i];
        }
};

int main()
{
    safearay A;
    cout << "A[2] = " << A[2] << endl;
    cout << "A[5] = " << A[5] << endl;
    cout << "A[12] = " << A[12] << endl;
    return 0;
}

运行结果：

exbot@ubuntu:~/wangqinghe/C++/20190809$ g++ subscript.cpp -o subscript

exbot@ubuntu:~/wangqinghe/C++/20190809$ ./subscript

A[2] = 2

A[5] = 5

the index is too big

A[12] = 0