#include<iostream>
#include<cstring>
/*
1.串声明
创建
删除
获取长度
串索引
串赋值
串比较
串拷贝
串拼接
串输出
*/

using namespace std;
class MyString{
    private:
        char* m_string;
        size_t size;
    public:
    //串输出
        friend ostream& operator<<(ostream& os,MyString& str);
    //默认构造
        MyString() : size(0) {
            m_string = new char[1];
            m_string[0] = '\0';
        }
    //参数构造
        MyString(const char* value) : size(strlen(value)) {
            m_string = new char[size+1];
            strcpy(m_string,value);
        }
    //拷贝构造
        MyString(MyString& other) : size(other.size) {
            m_string = new char[other.size+1];
            strcpy(m_string,other.m_string);
        }
    //移动构造
        MyString(MyString&& other) noexcept : size(other.size),m_string(other.m_string){
            other.m_string = nullptr;
            other.size = 0;
        }
    //析构
        ~MyString(){
            delete[] m_string;
        }

    //获取长度
        size_t getLength() const;
    //串的赋值string a =“”
        MyString& operator=(const char* string);
        //string a
        //string b a=b
        MyString& operator=(MyString& string);
        MyString& operator=(MyString str);
    //串的比较 
        bool operator==(MyString& str);
        bool operator!=(MyString& str);

    //串索引
        char& operator[](size_t index);

    //串拼接
        MyString operator+(MyString& str);
 
};

size_t MyString::getLength() const{
    return size;
}


bool MyString::operator==(MyString& str){
    return strcmp(m_string,str.m_string) == 0;
}

bool MyString::operator!=(MyString& str){
    return strcmp(m_string,str.m_string) != 0;
}
//若干个=重载
MyString& MyString::operator=(const char* string){
    if(this->m_string != string){
    size_t new_size = strlen(string);
    delete[] m_string;
    m_string = new char[new_size + 1];
    strcpy(m_string,string);
    size = strlen(string);

    }
       return *this;
  
}

MyString& MyString::operator=(MyString& string){
    if(*this != string){
    delete[] m_string;
    m_string = new char[string.size + 1];
    strcpy(m_string,string.m_string);
    size = string.size;

    }
       return *this;
  
}

MyString& MyString::operator=(MyString string){
    if(*this != string){
    delete[] m_string;
    m_string = new char[string.size + 1];
    strcpy(m_string,string.m_string);
    size = string.size;

    }
       return *this;
  
}
//////////////////////
char& MyString::operator[](size_t index){
    return m_string[index];
}

 MyString MyString::operator+(MyString& str){
    MyString result;
    size_t new_size = strlen(m_string) + strlen(str.m_string);
    char* new_string = new char[new_size+1];
    strcpy(new_string,m_string);
    strcat(new_string,str.m_string);
    result = new_string;
    return new_string;
 }

ostream& operator<<(ostream& os,MyString& str){
    os << str.m_string;
    return os;
 }

 int main(){
    MyString str;//测试默认构造
    MyString str1("BISTU");//测试参数构造
    str = "ABCD";//测试赋值运算符重载
    MyString str2(str); //测试拷贝构造
    cout << "str1:" << str1 << endl;
    cout << "str:" << str << endl;
    cout << "str2:" << str2 << endl;
    cout << "str1的长度为:" << str1.getLength() << endl;//测试getlength()
    //测试比较运算符重载
    if(str1 == str2){ 
        cout << "str1 = str2" << endl;
    }else cout << "str1 != str2" << endl;

    if(str != str2){ 
        cout << "str != str2" << endl;
    }else cout << "str = str2" << endl;

    MyString str3(str1 + str);//同时测试移动构造和+重载
    cout << str3 << endl;
    return 0;
 }