Why specify class name when declaring member functions?

Question

class C : public B
{
public:
    void C::Test();
};

What is the point of specifying C in the declaration of the member function?

Answer 1

You shouldn't do this. Many modern compilers will treat this as a syntax error, for example, g++ 4.2.1 will!

Answer 2

This is only neccessary when defining the method outside of the class:

class C : public B
{
public:
    void Test();
};

void C::Test() { ... }