benlaug benlaug - 1 month ago 19
C++ Question

Is std::vector copying the objects with a push_back?

After a lot of investigations with valgrind, I've made the conclusion that std::vector makes a copy of an object you want to push_back.

Is that really true ? A vector cannot keep a reference or a pointer of an object without a copy ?!

Thanks

Answer

Yes, std::vector<T>::push_back() creates a copy of the argument and stores it in the vector. If you want to store pointers to objects in your vector, create a std::vector<whatever*> instead of std::vector<whatever>.

However, you need to make sure that the objects referenced by the pointers remain valid while the vector holds a reference to them (smart pointers utilizing the RAII idiom solve the problem).

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