Protected access modifier is similar to that of private access modifiers, the difference is that the class member declared as Protected are inaccessible outside the class but they can be accessed by any subclass(derived class) of that class.
Example:
// C++ program to demonstrate // protected access modifier #include <bits/stdc++.h> using namespace std;
// base class class Parent {
// protected data members
protected :
int id_protected;
}; // sub class or derived class class Child : public Parent {
public :
void setId( int id)
{
// Child class is able to access the inherited
// protected data members of the base class
id_protected = id;
}
void displayId()
{
cout << "id_protected is: "
<< id_protected << endl;
}
}; // main function int main()
{ Child obj1;
// member function of the derived class can
// access the protected data members of the base class
obj1.setId(81);
obj1.displayId();
return 0;
} |
id_protected is: 81
The class members declared as private can be accessed only by the functions inside the class. They are not allowed to be accessed directly by any object or function outside the class. Only the member functions or the friend functions are allowed to access the private data members of a class.
Example:
// C++ program to demonstrate private // access modifier #include <iostream> using namespace std;
class Circle {
// private data member
private :
double radius;
// public member function
public :
void compute_area( double r)
{
// member function can access private
// data member radius
radius = r;
double area = 3.14 * radius * radius;
cout << "Radius is: " << radius << endl;
cout << "Area is: " << area;
}
}; // main function int main()
{ // creating object of the class
Circle obj;
// trying to access private data member
// directly outside the class
obj.compute_area(1.5);
return 0;
} |
Radius is: 1.5 Area is: 7.065
Difference between Private and Protected
Private | Protected |
---|---|
The class members declared as private can be accessed only by the functions inside the class. | Protected access modifier is similar to that of private access modifiers. |
Private members keep implementation details in a program. | Protected members enhanced access for derived classes. |
Only the member functions or the friend functions are allowed to access the private data members of a class. | The class member declared as Protected are inaccessible outside the class but they can be accessed by any subclass(derived class) of that class. |
Private member are not inherited in class. | Protected member are inherited in class. |