C++私有成员

#include <iostream>

using namespace std;

class Box {
   public:
      double length;
      voID setWIDth( double wID );
      double getWIDth( voID );

   private:
      double wIDth;
};

// Member functions deFinitions
double Box::getWIDth(voID) {
   return wIDth ;
}

voID Box::setWIDth( double wID ) {
   wIDth = wID;
}

// Main function for the program
int main() {
   Box Box;

   // set Box length without member function
   Box.length = 10.0; // OK: because length is public
   cout << "Length of Box : " << Box.length <<endl;

   // set Box wIDth without member function
   // Box.wIDth = 10.0; // Error: because wIDth is private
   Box.setWIDth(10.0);  // Use member function to set it.
   cout << "WIDth of Box : " << Box.getWIDth() <<endl;

   return 0;
}