c++--class static member data

    // defines a static member data in a class that does not belong to this class object, and all programs share this member     // the member's memory is in the global data area and is not placed    inside the stack. // through the class, the object is given directly, and the object is    in the stack area; // a new object is created by the object pointer in the heap    area; // a static function in a class can only access static data members, and ordinary data members in a class cannot be accessed. 

c++--class static member data