Why can't I use reference types as the value type of a container type?

Question

For example, std::vector<int&> vec_int; this seems to be invalid in c++. Why is this invalid?

Answer 1

STL containers need to be able to construct objects with default constructor. You cannot do that with a reference. A reference is guaranteed to be valid, therefore it always has to be initialized with assignment.

You need to use a pointer instead.