#include <cstdlib>

 #include <cstring>

 class Mystring

 {

 public:

     Mystring(const char * pdata)

     {

         if(pdata==NULL)

         {

             data = new char[];

             *data = '\0';

         }

         else

         {

             int len = strlen(pdata);

             data = new char[len+];

             strcpy(data,pdata);

         }

     }

     Mystring(const Mystring &str)

     {

         int len = strlen(str.data);

         data = new char[len+];

         strcpy(data,str.data);

     }

     Mystring &operator=(const Mystring &str)

     {

         if(this!=&str)

         {

             Mystring strTemp(str);

             char *pTemp = strTemp.data;

             strTemp.data = this->data;

             this->data = pTemp;

         }

         return this;

     }

     ostream & operator<<(ostream &os,const Mystring &str)

     {

         os<<str.data;

         return os;

     }

     Mystring & operator+(const Mystring & str)const

     {

         if(str.data!=NULL)

         {

             int len1 = strlen(str.data);

             int len2 = strlen(this->data);

             Mystring strTemp(*(this->data));//创建一个临时对象保存原来对象的数据

             delete []data;//删除原来的数据

             data=NULL;

             data = new char[len1+len2+];//开闭新的空间

             strcpy(data,strTemp.data);//复制

             strcat(data,str.data);//拼接

         }

         return this;

     }

     char & operator[](int index)//char返回引用，是为了我们之后可以修改字符串

     {

         int len = strlen(data);

         if(index>len||index<)

         {

             perror("index is not in the cope!");

             exit();

         }else

             return *((this->data)+index);

     }

     ~Mystring()

     {

         delete []data;

     }

 private:

     char * data;

 };