const vector implies const elements?

Question

Does const vector mean that its elements are constas well?

In the code below,

v[0].set (1234); in void g (

Answer 1

So a const object can only call const methods. That is:

class V {
  public:
    void foo() { ... }        // Can't be called
    void bar() const  { ... } // Can be called
};

So let's look at a vector's operator[]:

reference       operator[]( size_type pos );
const_reference operator[]( size_type pos ) const;

So when the vector object is const, it will return a const_reference.

About: (*v[0]).set(1234);

Let's break this down:

A * const & ptr = v[0];
A & val = *ptr;
val.set(1234);

Note that you have a constant pointer to variable data. So you can't change what is pointed at, but you can change the value that the pointer points at.