Are classes namespaces in C++?

Question

Are classes namespaces in C++? I am asking this because the following code is valid. Could someone explain why?

Code:

#include <iostream>

class MainClass{
public:
  enum Bool{False, True};

  MainClass(){
    std::cout << "MainClass constructor" << True << std::endl;
  }
  ~MainClass(){
    std::cout << "MainClass destructor" << std::endl;
  }
};

int main(){
  MainClass::Bool myvar = MainClass::False << std::endl; //Why is this line valid?
  std::cout << myvar;
  return 0;
}

Answer 1

Classes are not namespaces. However the Bool enum is defined in MainClass's scope, so the scope resolution operator :: applies.

Answer 2

In C++ there is a namespace and there is also a class, a namespace is not a class. Your code is valid because you can nest enums, structs, classes, etc, within classes.