C++中声明类的class与声明结构体的struct关键字详解

   [template-spec]
    class [ms-decl-spec] [tag [: base-list ]]
{
  member-list
} [declarators];
[ class ] tag declarators;

// class.cpp
// compile with: /EHsc
// Example of the class keyword
// Exhibits polymorphism/virtual functions.

#include <iostream>
#include <string>
#define TRUE = 1
using namespace std;

class dog
{
public:
  dog()
  {
   _legs = 4;
   _bark = true;
  }

  void setDogSize(string dogSize)
  {
   _dogSize = dogSize;
  }
  virtual void setEars(string type)   // virtual function
  {
   _earType = type;
  }

private:
  string _dogSize, _earType;
  int _legs;
  bool _bark;

};

class breed : public dog
{
public:
  breed( string color, string size)
  {
   _color = color;
   setDogSize(size);
  }

  string getColor()
  {
   return _color;
  }

  // virtual function redefined
  void setEars(string length, string type)
  {
   _earLength = length;
   _earType = type;
  }

protected:
  string _color, _earLength, _earType;
};

int main()
{
  dog mongrel;
  breed labrador("yellow", "large");
  mongrel.setEars("pointy");
  labrador.setEars("long", "floppy");
  cout << "Cody is a " << labrador.getColor() << " labrador" << endl;
}

[template-spec] struct[ms-decl-spec] [tag [: base-list ]]
{ 
  member-list 
} [declarators];
[struct] tag declarators;

 #include <iostream>
using namespace std;

struct PERSON {  // Declare PERSON struct type
  int age;  // Declare member types
  long ss;
  float weight;
  char name[25];
} family_member;  // Define object of type PERSON

struct CELL {  // Declare CELL bit field
  unsigned short character : 8; // 00000000 ????????
  unsigned short foreground : 3; // 00000??? 00000000
  unsigned short intensity : 1; // 0000?000 00000000
  unsigned short background : 3; // 0???0000 00000000
  unsigned short blink   : 1; // ?0000000 00000000
} screen[25][80];    // Array of bit fields 

int main() {
  struct PERSON sister;  // C style structure declaration
  PERSON brother;  // C++ style structure declaration
  sister.age = 13;  // assign values to members
  brother.age = 7;
  cout << "sister.age = " << sister.age << '\n';
  cout << "brother.age = " << brother.age << '\n';

  CELL my_cell;
  my_cell.character = 1;
  cout << "my_cell.character = " << my_cell.character;
}
// Output:
// sister.age = 13
// brother.age = 7
// my_cell.character = 1