不必要背代码，语法到处都是，但是要熟悉实现逻辑，需求分析，以及对于具体的实现细节进行推敲，比如扩容机制、上下界限等问题的处理。

1.需求分析

• 构造操作
  1.三个构造：构造函数、（深）拷贝构造函数和移动构造函数。
  2.两个赋值：（深）拷贝赋值运算符和移动赋值运算符。
  3.一个析构：析构函数释放内存，防止内存泄漏。

• 运算符：
  1.重载 [] 运算符，用于访问字符串中的字符，并提供 const 和非 const 版本。
  2.重载 + 运算符，用于字符串拼接。
  3.重载 == 和 != 运算符用于字符串比较。
  4.重载 << 和 >> 运算符，用于输入输出操作。
  5.重载 =

• 异常
  1.越界异常

知识点：三个构造、动态内存管理、RAII、深拷贝与移动语义、运算符重载、异常处理等。

2.代码实现

#include <iostream>
#include <cstring>  // For strlen, strcpy, etc.class MyString {
private:char* data;  // Pointer to the dynamically allocated arraysize_t length;  // Length of the string (not including null terminator)public:// Default constructorMyString() : data(nullptr), length(0) {}// Constructor from C-stringMyString(const char* str) {if (str) {length = std::strlen(str);data = new char[length + 1];  // Allocate memory for stringstd::strcpy(data, str);  // Copy string into memory} else {data = nullptr;length = 0;}}// Copy constructor (deep copy)MyString(const MyString& other) {length = other.length;if (other.data) {data = new char[length + 1];std::strcpy(data, other.data);} else {data = nullptr;}}// Move constructor (no deep copy, just transfer ownership)MyString(MyString&& other) noexcept : data(other.data), length(other.length) {other.data = nullptr;  // Release ownership of the old stringother.length = 0;}// Copy assignment operator (deep copy)MyString& operator=(const MyString& other) {if (this == &other) {return *this;  // Handle self-assignment}// Free existing memorydelete[] data;// Perform deep copylength = other.length;if (other.data) {data = new char[length + 1];std::strcpy(data, other.data);} else {data = nullptr;}return *this;}// Move assignment operator (transfer ownership)MyString& operator=(MyString&& other) noexcept {if (this == &other) {return *this;  // Handle self-assignment}// Free existing memorydelete[] data;// Transfer ownershipdata = other.data;length = other.length;other.data = nullptr;other.length = 0;return *this;}// Destructor (free the allocated memory)~MyString() {delete[] data;}// Get length of the stringsize_t size() const {return length;}// Overload operator[] to access characterschar& operator[](size_t index) {if (index >= length) {throw std::out_of_range("Index out of bounds");}return data[index];}const char& operator[](size_t index) const {if (index >= length) {throw std::out_of_range("Index out of bounds");}return data[index];}// Overload operator+ for string concatenationMyString operator+(const MyString& other) const {MyString newStr;newStr.length = length + other.length;newStr.data = new char[newStr.length + 1];// Copy first stringstd::strcpy(newStr.data, data);// Concatenate second stringstd::strcat(newStr.data, other.data);return newStr;}// Overload operator== for string comparisonbool operator==(const MyString& other) const {return std::strcmp(data, other.data) == 0;}// Overload operator!= for string comparisonbool operator!=(const MyString& other) const {return !(*this == other);}// Output stream overload (printing the string)friend std::ostream& operator<<(std::ostream& os, const MyString& str) {if (str.data) {os << str.data;}return os;}// Input stream overload (reading the string)friend std::istream& operator>>(std::istream& is, MyString& str) {char buffer[1000];  // Assume max input sizeis >> buffer;str = MyString(buffer);  // Use the constructor to assignreturn is;}
};int main() {// Example usage of MyString classMyString str1("Hello");MyString str2(" World");// ConcatenationMyString str3 = str1 + str2;std::cout << "Concatenated string: " << str3 << std::endl;// Comparisonif (str1 == MyString("Hello")) {std::cout << "str1 is equal to 'Hello'" << std::endl;}// AssignmentMyString str4;str4 = str3;std::cout << "Assigned string: " << str4 << std::endl;// Input and OutputMyString inputStr;std::cout << "Enter a string: ";std::cin >> inputStr;std::cout << "You entered: " << inputStr << std::endl;return 0;
}

3.编译运行

[jn@jn build]$ ./a.out
Concatenated string: Hello World
str1 is equal to 'Hello'
Assigned string: Hello World
Enter a string: WWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW
You entered: WWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW
[jn@jn build]$