Namespaces qualified with :: in C++

Question

What does it mean if namespace in C++ is qualified with ::? For example ::testing::Test.

Answer 1

I if you precede a variable name with ::, it resolves the variable to the global scope. In this way, you can have both a local variable testing and global variable testing and differentiate between them.

#include 

using namespace std;
int testing = 37;

int main()
{
   int testing = 42;

   cout << ::testing << ' ' << testing << endl;
}

Output will be 37 42