#include<iostream.h>
#include<string.h>
class mystring{
 int length;
 char* string;
public:
 mystring(){string=NULL;length=0;}
 mystring(const char*);
 mystring(const mystring&);
 ~mystring(){delete string;}
 mystring& operator=(const mystring&);
 friend ostream& operator<<(ostream&,mystring&);
 void operator+=(char*);
 friend void operator+=(char*,mystring&);
 void operator+=(mystring&);
 char& operator[](int x);
};
mystring::mystring(const char* str)
{
 length=strlen(str)+1;
 string=new char[length];
 strcpy(string,str);
}
mystring::mystring(const mystring& str)
{
 length=str.length;
 string=new char[length];
 strcpy(string,str.string);
}
mystring& mystring::operator =(const char& str)
{
 if(this != &str){
  length=str.length;
  string=new char[length];
  strcpy(string,str.string);
 }
 return *this;
}
void mystring::operator +=(char* str)
{
 char* buffer;
 length+=(strlen(str)+1);
 buffer=new char[length];
 strcpy(buffer,string);
 strcat(buffer,str);
 delete string;
 string=buffer;
}
void operator+=(char* str,mystring& obj)
{
 obj.length=obj.length+strlen(str)+1;
 char* buffer;
 buffer=new char[obj.length];
 strcpy(buffer,str);
 strcat(buffer,obj.string);
 delete obj.string;
 obj.string=buffer;
}
void mystring::operator +=(mystring& str)
{
 char* buffer;
 length+=(strlen(str.string)+1);
 buffer=new char[length];
 strcpy(buffer,string);
 strcat(buffer,str.string);
 delete string;
 string=buffer;
}
ostream& operator<<(ostream& sout,mystring x)
{
 sout<<x.string<<endl;
 return sout;}
inline char& mystring::operator [](int x)
{
 return string[x];
}
void main()
{
 mystring object("William"),
  lesson("Joseph"),grid("Heinze");
 cout<<object;
 object+="Heinze";
 cout<<object;
 cout<<lesson;
 "William"+=lesson;
 cout<<lesson;
 lesson+=grid;
 cout<<lesson;
 lesson[0]=\'w\';
 cout<<lesson;
}

왜안돌아가는지 모르겠어요 고쳐주세요 ㅠ