operator about the string of C + + =

In C + + primer 5, in the section on string, there is this sentence:

string " Hiya ";  // Copy Initialization

In other words, this is the copy initialization, which is called the copy constructor. And the following sentence:

string S6 ("hiya"//  Direct Initialization

But it is also directly initialized, and then I think, in the initialization of C + + above these two are not equivalent? In addition I am also very curious in the implementation of the string string s5 = "Hiya"; If it is true that the copy is initialized, there is no intermediate generation of a temporary variable (though it is unlikely that the write efficiency is obviously very low). So go to see the SGI STL source code, find about operator = part is this:

  operator= (const _chart* __s)  /  WC: = char*    return Assign (__s, _ _s + _traits::length (__s)); }

It is clear that there is no intermediate variable to produce.

I used these two ways to step through vs:

int Main (intChar* argv[]) {       int0;    string " WC " ;    string str2 ("wcww");          return 0

It is then found that both of these initialization statements enter the same constructor, which is the following:

    Basic_string (const _elem *_ptr)        : _mybase ()        {    //  construct from [_ptr, <null>)        _tidy ();        Assign (_ptr);        }

And this is not a copy constructor, just a general constructor. So the structure of the top two sentences belongs to the direct structure without copy construction.

operator about the string of C + + =