#include <iostream>
#include <string.h>

using namespace std;

class myString{
private:
    char *str;  //记录c风格的字符串
    int size;   //记录字符串的实际长度
public:
    //无参构造
    myString():size(10){
        str=new char[size];
        strcpy(str,"");
    }
    //有参构造
    myString(const char* s){
        size = strlen(s);
        str = new char[size+1];
        strcpy(str,s);
    }
    //析构函数
    ~myString(){
        cout<<"myString::析构函数"<<endl;
    }
    //拷贝构造
    myString(const myString& other):
        str(new char( *(other.str) )),
        size(other.size){
        cout<<"myString::拷贝构造"<<endl;
    }
    //拷贝赋值函数
    myString& operator =(const myString& other){
        if(this != &other){
            this->str=other.str;
            this->size=other.size;
        }
        cout<<"myString::拷贝赋值函数"<<endl;

        return *this;
    }
    //判空函数
    bool isempty(){
        return (this->size<=0)? 0:1;
    }
    //size函数
    int mySize(){
        return this->size;
    }
    //c_str
    char *c_str(){
        return this->str;
    }
    //at
    char& at(int pos){
        if(pos>=this->size || pos<0){
            return (this->str[0]);
        }else{
            return this->str[pos];
        }
    }
    //成员函数版实现加号运算符重载
    const myString operator+ (const myString &s)const{
        myString temp;
       // delete temp;
        strcat(temp.str,strcat(this->str,s.str));
        temp.size = this->size + s.size;
        return  temp;
    }
};

int main()
{
    myString s1("123abc");
    if(!s1.isempty()){
        cout<<"为空"<<endl;
    }else {
        cout<<"不为空"<<endl;
    }
    cout<<"size="<<s1.mySize()<<endl;
    cout<<"c_str="<<s1.c_str()<<endl;
    cout<<"at="<<s1.at(2)<<endl;

    myString s2;
    s2 =s1 + s1;
    cout<<"s2->size="<<s2.mySize()<<endl;

    return 0;
}