深入解析C++编程中范围解析运算符的作用及使用

namespace NamespaceA{
  int x;
  class ClassA {
  public:
    int x;
  };
}

int main() {

  // A namespace name used to disambiguate
  NamespaceA::x = 1;

  // A class name used to disambiguate
  NamespaceA::ClassA a1;
  a1.x = 2;

}

namespace NamespaceA{
  int x;
}

int x; 

int main() {
  int x;

  // the x in main()
  x = 0; 
  // The x in the global namespace
  ::x = 1; 

  // The x in the A namespace
  NamespaceA::x = 2; 
}

namespace NamespaceB {
  class ClassB {
  public:
    int x;
  };
}

namespace NamespaceC{
  using namespace B;

}
int main() {
  NamespaceB::ClassB c_b;
  NamespaceC::ClassB c_c;

  c_b.x = 3;
  c_c.x = 4;
}

namespace NamespaceD{
  namespace NamespaceD1{
    int x;
  }
}

namespace NamespaceE{

  class ClassE{
  public:
    class ClassE1{
    public:
      int x;
    };
  };
}

int main() {
  NamespaceD:: NamespaceD1::x = 6;
  NamespaceE::ClassE::ClassE1 e1;
  e1.x = 7 ;
}

class ClassG {
public:
  static int get_x() { return x;}
  static int x;
};

int ClassG::x = 6;

int main() {

  int gx1 = ClassG::x;
  int gx2 = ClassG::get_x(); 
}

enum class EnumA{
  First,
  Second,
  Third
};

int main() {

  EnumA enum_value = EnumA::First;
}