:: Story about range resolution operators

Abput Author：

• Global scope（::name）：Used before a type name (class, class member, member function, variable, etc.), indicates that the scope is a global namespace
• Class scope（class::name）：The scope used to represent the specified type is class specific
• Namespace scope（namespace::name）: The scope used to represent the specified type is a namespace specific

Code ：maohao.cpp