LANGUAGE PROTECTED MEMBERS

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C++ LANGUAGE PROTECTED MEMBERS

The protected Members 


A protected member variable or function is very similar to a private 
member but it provided one additional benefit that they can be 
accessed in child classes which are called derived classes. 
You will learn derived classes and inheritance in next chapter. 
For now you can check following example where I have derived one 
child class SmallBox from a parent class Box. 
Following example is similar to above example and here width member 
will be accessible by any member function of its derived class SmallBox. 


#include <iostream> 
using namespace std; 
  
class Box 
{ 
   protected: 
      double width; 
}; 
  
class SmallBox:Box // SmallBox is the derived class. 
{ 
   public: 
      void setSmallWidth( double wid ); 
      double getSmallWidth( void ); 
}; 
  
// Member functions of child class 
double SmallBox::getSmallWidth(void) 
{ 
    return width ; 
} 
  
void SmallBox::setSmallWidth( double wid ) 
{ 
    width = wid; 
} 
  
// Main function for the program 
int main( ) 
{ 
   SmallBox box; 
  
   // set box width using member function 
   box.setSmallWidth(5.0); 
   cout << "Width of box : "<< box.getSmallWidth() << endl; 
  
   return 0; 
} 


When the above code is compiled and executed, 
it produces the following result: 


Width of box : 5