What is the meaning of prepended double colon "::"?

Question

I found this line of a code in a class which I have to modify: ::Configuration * tmpCo = m_configurationDB;//pointer to current db and I don't know what exactly means the double colon prepended to the class name. Without that I would read: declaration of `tmpCo` as a pointer to an object of the class `Configuration`... but the prepended double colon confuses me. I also found: typedef ::config::set ConfigSet;

Answer 1

Double colons are used to refer to types of namespaces for example without using the std namespace you would have to type "std::cout << 'Hello, World' << endl;" instead of a normal "cout << 'Hello, World' << endl;"