C++ copy constructor clear up on vector<Base*> of Derived* -

i have class uses class of base pointers derived objects, need have own desructor deleting vector's elements , custom copy , assignment funcitons. i'm not entirely sure preferred way of implementing structure below , writing right copy , assignment constructors , destructors it. may ask guide me? i've read lot , searched i'm still not sure.

class base  {    public:    base();    ~virtual base();     int a;    int type; // derived1 or derived2    std::string b;    ... }  class derived1 : public base  { public:     derived1();     derived1(const base* a);     virtual ~derived1(); }  class derived1  {     derived1::derived1(const base *a) : base(a)      {      } }  class derived2 : public base { public:     derived2();     derived2(const base* a);     virtual ~derived2();      std::string d1;     std::string d2;     int d3; }  class derived2  {     derived2::derived2(const base *a) : base(a) {         this->d1 = ((derived2*)a)->d1;         this->d2 = ((derived2*)a)->d2;         this->d3 = ((derived2*)a)->d3;     } }   class  { public:     a();     ~a();     a(const a& a);     a& operator = (const a& a);      std::string somestring;     std::vector<base*> vect; }  a::~a() {     std::vector<base*>::iterator = vect.begin();     while (it != vect.end()) {         delete (*it);         it++; }  a::a(const &a) {     somestring = a.somestring;     for(std::size_t = 0; < a.vect.size(); ++i {         somestring = a.somestring;         base* base = a.vect.at(i);         if(base->type == base::typed1) {             base = new derived1( a.vect.at(i) );             vect.push_back( base );         }         else {             base = new derived2( a.vect.at(i) );             vect.push_back( base );         }     } } 

your loop in destructor fine in practice, , usual solution. formally, undefined behavior, since leaving objects in vector (pointers deleted objects) aren't copiable, in practice: vector won't copy them unless resize bigger, or insert or erase on it. if want avoid undefined behavior:

for ( auto current = vect.begin(); current != vect.end(); ++ current ) {     base* tmp = *it;     *it = nullptr;     delete tmp; } 

but 1 case wouldn't bother (and tend more sensitive undefined behavior most).