头文件

#ifndef MY_STRING_H
#define MY_STRING_H#include <iostream>class My_string
{
private:char *ptr; // 指向字符数组的指针int size;  // 字符串的最大容量int len;   // 字符串的当前长度public:My_string();My_string(const char *src);My_string(const My_string &src);My_string& operator=(const My_string &src);~My_string();void push_back(char value);void pop_back();char &at(int index);void clear();char *data() const;int get_length() const;int get_size() const;bool is_empty() const;// 运算符重载My_string operator+(const My_string &other) const;My_string operator+(char value) const;char &operator[](int index);bool operator>(const My_string &other) const;bool operator<(const My_string &other) const;bool operator==(const My_string &other) const;bool operator>=(const My_string &other) const;bool operator<=(const My_string &other) const;bool operator!=(const My_string &other) const;My_string& operator+=(const My_string &other);My_string& operator+=(char value);friend std::ostream& operator<<(std::ostream &out, const My_string &str);friend std::istream& operator>>(std::istream &in, My_string &str);
};#endif // MY_STRING_H

 源文件

#include "My_string.h"
#include <iostream>
#include <cstring>
#include <stdexcept> // 用于异常处理using namespace std;// 默认构造函数
My_string::My_string() : size(15), len(0)
{this->ptr = new char[size];this->ptr[0] = '\0';
}// 带参数的构造函数
My_string::My_string(const char *src)
{this->len = strlen(src);this->size = this->len + 1;this->ptr = new char[size];strcpy(this->ptr, src);
}// 拷贝构造函数
My_string::My_string(const My_string &src)
{this->len = src.len;this->size = src.size;this->ptr = new char[size];strcpy(this->ptr, src.ptr);
}// 赋值运算符重载
My_string& My_string::operator=(const My_string &src)
{if (this == &src)return *this;delete[] this->ptr;this->len = src.len;this->size = src.size;this->ptr = new char[size];strcpy(this->ptr, src.ptr);return *this;
}// 尾部插入
void My_string::push_back(char value)
{if (len + 1 >= size){size *= 2;char *new_ptr = new char[size];strcpy(new_ptr, ptr);delete[] ptr;ptr = new_ptr;}ptr[len++] = value;ptr[len] = '\0';
}// 尾部删除
void My_string::pop_back()
{if (len > 0){len--;ptr[len] = '\0';}
}// 通过索引访问字符
char &My_string::at(int index)
{if (index < 0 || index >= len){throw out_of_range("Index out of range");}return ptr[index];
}// 清空字符串
void My_string::clear()
{len = 0;ptr[0] = '\0';
}// 返回 C 风格字符串
char *My_string::data() const
{return ptr;
}// 返回字符串长度
int My_string::get_length() const
{return len;
}// 返回最大容量
int My_string::get_size() const
{return size;
}// 判空函数
bool My_string::is_empty() const
{return len == 0;
}// 运算符重载实现
My_string My_string::operator+(const My_string &other) const
{My_string result;result.size = len + other.len; result.ptr = new char[result.size + 1];strcpy(result.ptr, ptr);        // 复制当前字符串strcat(result.ptr, other.ptr);  // 追加另一个字符串result.len = len + other.len;   // 更新长度return result;
}My_string My_string::operator+(char value) const
{My_string result(*this); // 拷贝当前对象result.push_back(value); // 添加字符return result;
}char &My_string::operator[](int index)
{return at(index); // 使用 at 函数检查边界
}bool My_string::operator>(const My_string &other) const
{return strcmp(ptr, other.ptr) > 0;
}bool My_string::operator<(const My_string &other) const
{return strcmp(ptr, other.ptr) < 0;
}bool My_string::operator==(const My_string &other) const
{return strcmp(ptr, other.ptr) == 0;
}bool My_string::operator>=(const My_string &other) const
{return *this >= other;
}bool My_string::operator<=(const My_string &other) const
{return this <= other;
}bool My_string::operator!=(const My_string &other) const
{return *this != other;
}My_string& My_string::operator+=(const My_string &other)
{this->push_back('\0'); // 确保字符串末尾有结束符strcat(this->ptr, other.ptr); len += other.len; // 更新长度return *this;
}My_string& My_string::operator+=(char value)
{push_back(value); // 尾部添加字符return *this;
}// 输入输出运算符重载
ostream& operator<<(ostream &out, const My_string &str)
{out << str.ptr;return out;
}istream& operator>>(istream &in, My_string &str)
{char buffer[1024]; in >> buffer;str.clear(); // 清空当前字符串str.push_back('\0'); // 先设置为结束符for (int i = 0; buffer[i] != '\0'; i++){str.push_back(buffer[i]); }return in;
}// 析构函数
My_string::~My_string()
{delete ptr;
}

 主函数

#include "My_string.h"
#include <iostream>using namespace std;int main()
{My_string s1("hello");My_string s2(" world");My_string s3 = s1 + s2; // 字符串连接cout << "s3: " << s3 << endl; // 输出 "hello world"s1 += '!';cout << "s1 after +=: " << s1 << endl; // 输出 "hello!"// 测试 []cout << "s1[1]: " << s1[1] << endl; // 输出 'e'cout << "s1 > s2: " << (s1 > s2) << endl; // 输出 1 cout << "s1 < s2: " << (s1 < s2) << endl; // 输出 0 cout << "s1 == s2: " << (s1 == s2) << endl; // 输出 0 My_string s4;cout << "Enter a string: ";cin >> s4; // 输入字符串cout << "You entered: " << s4 << endl;return 0;
}