CODEWITHSUNDEEP
c++pointersvector
user3443903
user3443903

Reputation:

Vector of pointers to objects c++

I have a base class with 2 derived classes and another one which store objects of the derived classes type:

class X
{};

class X1 : public X
{};

class X2 : public X
{};

class Y
{
std::vector<X*> V;
};

why doesn't this method of introducing elements in V work?

X1 object;
X *ptr = &object;
V.push_back(ptr);

Upvotes: 0

Views: 1699

Answers (1)

πάντα ῥεῖ
πάντα ῥεῖ

Reputation: 1

I suppose you have put your sample code inside a function of class Y and can access the class member variable V.
The pointer to the locally declared object variable is invalid when the function returned. You can fix this by allocating an object from the heap:

X *ptr = new X();
V.push_back(ptr);

Or even better instead of using raw pointers, use smart pointers if possible, e.g:

class Y {
    std::vector<std::shared_ptr<X> > V;
};

V.push_back(std::make_shared<X>());

Upvotes: 3

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