In general, classes that possess pointers, file handles, and other resources need a user-defined constructor to avoid aliasing. For example:

 class Person {private:  int age;  char * name;public:   // the following three member functions must be defined by the class implementer   Person (const char * name, int age);  Person & operator= (const Person & other);   Person (const Person& other);};

Seemingly, there’s no escape from explicitly defining a copy constructor and assignment operator for class Person, or else the compiler-generated copy constructor and assignment operator will result in aliasing. However, the aliasing problem in this case results from the reliance on low-level language constructs (a bare pointer). Had class Person possessed an embedded std::string object instead of a pointer to char, the user-written copy constructor and assignment operator wouldn’t be needed. When a class needs user-defined assignment operator and copy constructor, it may indicate a design flaw rather than an unavoidable necessity.