Namespaces qualified with :: in C++

Question

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

Answer 1

If :: is used on the left side it means the global scope.

If you want an analogy with the filesystem, testing::Test would be a kind of relative path (with respect of König lookup) whereas ::testing::Test would be an absolute path. I hope this analogy makes it clearer and doesn't mess up your mind :-).