I have read the below post which gives a very good insight into move semantics:

> 
> [Can someone please explain move semantics to me?](https://stackoverflow.com/questions/3106110/can-someone-please-explain-move-semantics-to-me) 
> 
> 
> 

but I am still fail to understand following things regarding move semantics -

1. Does copy elision and RVO would still work for classes without move constructors?
2. Even if our classes doesn't have move constructors, but STL containers has one. For operation like

`std::vector<MyClass> vt = CreateMyClassVector();`

and to perform operations like sorting etc. Why can't STL internally leverage move semantics to improve such operations internally using operations like copy elision or RVO which doesn't require move constructors?

3.
Do we get benefited by move semantics in below case -

`std::vector< int > vt1(1000000, 5); // Create and initialize 1 million entries with value 5`

`std::vector< int > vt2(std::move(vt1)); // move vt1 to vt2`

as integer is a primitive type, moving integer elements will not offer any advantage.
or here after move operation vt2 simply points to vt1 memory in heap and vt1 is set to null. what is actually happening? If latter is the case then even point 2 holds that we may not need move constructor for our classes.

4.
 When a push\_back() is called using std::move on lvalue for e.g :

```
    std::vector<MyClass> vt;

    for(int i=0; i<10; ++i)
    {
        vt.push_back(MyClass());
    }

    MyClass obj;

    vt.push_back(std::move(obj));

```

now as vector has contiguous memory allocation, and obj is defined somewhere else in memory how would move semantics move the obj memory to vector vt contiguous memory region, wouldn't moving memory in this case is as good as copying memory, how does move justifies vectors contiguous memory requirements by simply moving a pointer pointing to a memory in different region of a heap.?

Thanks for explanation in advance!

[Originally posted as [Move semantics clarification](https://stackoverflow.com/questions/14603669/move-semantics-clarification) but now as the context is changed a bit posting it as new question shall delete the old one ASAP.]