c++ - 为 mystring 类重载数组运算符

Question

我需要帮助弄清楚如何为我必须创建的 MyString 类重载数组运算符。我已经把其他一切都弄清楚了，但出于某种原因，阵列给我带来了麻烦。

这是我的头文件:

#ifndef MYSTRING_H
#define MYSTRING_H

#include <iostream>
#include <cstring>  // For string library functions
#include <cstdlib>  // For exit() function
using namespace std;

// MyString class: An abstract data type for handling strings
class MyString
{
private:
    char *str;
    int len;
public:
    // Default constructor.
    MyString()
    { 
        str = 0; 
        len = 0;
    }
     
    // Convert and copy constructors. 
    MyString(char *);
    MyString(MyString &);
    
    // Destructor. 
    ~MyString()
    { 
        if (len != 0)
            delete [] str;
        str = 0;
        len = 0;
    }
     
    // Various member functions and operators.   
    int length() { return len; }
    char *getValue() { return str; };
    MyString operator+=(MyString &);
    MyString operator+=(const char *);
    MyString operator=(MyString &);
    MyString operator=(const char *);
    bool operator==(MyString &);
    bool operator==(const char *);
    bool operator!=(MyString &);
    bool operator!=(const char *);
    bool operator>(MyString &);
    bool operator>(const char *);
    bool operator<(MyString &);
    bool operator<(const char *);
    bool operator>=(MyString &);
    bool operator>=(const char*);
    bool operator<=(MyString &);
    bool operator<=(const char *);
    MyString operator [](MyString *);
    
    // Overload insertion and extraction operators.
    friend ostream &operator<<(ostream &, MyString &);
    friend istream &operator>>(istream &, MyString &);
};
#endif

MyString::operator [] 的正文会是什么样子？

MyString MyString::operator [](MyString *)
{
    ... what goes here
}

Answer 1

对给定类的对象使用数组运算符的语法是:

MyString s("Test");
char c = s[0];

函数的参数是一个整数值。

因此，运算符需要声明为:

// The non-const version allows you to change the 
// content using the array operator.
char& operator [](size_t index);

// The nconst version allows you to just get the 
// content using the array operator.
char operator [](size_t index) const;