Question

namespace MyNamespace
{
    static void foo1()
    {

    }
}

using namespace MyNamespace;

class MyClass
{
    void foo2()
    {
        ::foo1();
    }    
};

The scope resolution operation :: means using method in the global namespace. Here we can use ::foo1(). This means method foo1() is in the global namespace, am I right?

My question is, does using namespace ANAMESPACE_NAME mean we import all elements form the namespace ANAMESPACE_NAME into the global namespace?

Answer 1

Section 3.4.3.4 of the C++2003 standard has an answer:

A name prefixed by the unary scope operator :: (5.1) is looked up in
global scope, in the translation unit where it is used. The name shall
be declared in global namespace scope or shall be a name whose
declaration is visible in global scope because of a using-directive
(3.4.3.2).

This paragraph is almost identical in the C++11 FDIS, so this probably also holds in C++11.