In this post, we are going to learn about access modifiers behaves from the parent-child relationship.
The private member cannot be passed down through the generations. If we change the visibility mode to the public, however, we lose the benefit of data hiding.
Protected is a third visibility modification introduced by C++. All member functions inside the class, as well as the class that is directly derived from it, will have access to the protected member.
There are three different types of visibility modes:
public:
When a member is made public, it is available to all of the program’s operations.
private:
When a member is marked private, it can only be accessed by other members of the class.
protected:
When a member is designated protected, it is available both within its own class and the class that is derived from it immediately.
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The Inherited Visibility Members Are:
| Base class visibility | Derived class visibility | ||
|---|---|---|---|
| Public | Private | Protected | |
| Private | Not Inherited | Not Inherited | Not Inherited |
| Protected | Protected | Private | Protected |
| Public | Public | Private | Protected |
Parent Class Inherited To Child Class As Public:
//Access Modifiers In C++
#include <iostream>
using namespace std;
class Parent
{
public:
Parent()
{
cout << "Parent Constructor." << endl;
}
};
class Child : public Parent
{
public:
Child()
{
cout << "Child Constructor." << endl;
}
};
int main()
{
Child C;
return 0;
}Output:
Parent Constructor.
Child Constructor.Parent Class Inherited To Child Class As Private:
//Access Modifiers In C++
#include <iostream>
using namespace std;
class Parent
{
public:
Parent()
{
cout << "Parent Constructor." << endl;
}
};
class Child : private Parent
{
public:
Child()
{
cout << "Child Constructor." << endl;
}
};
int main()
{
Child C;
return 0;
}Output:
Parent Constructor.
Child Constructor.Join Our Community
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Parent Class Inherited To Child Class As Protected:
//Access Modifiers In C++
#include <iostream>
using namespace std;
class Parent
{
public:
Parent()
{
cout << "Parent Constructor." << endl;
}
};
class Child : protected Parent
{
public:
Child()
{
cout << "Child Constructor." << endl;
}
};
int main()
{
Child C;
return 0;
}Output:
Parent Constructor.
Child Constructor.Now, To Change Parent Class Members As Public, Private and Protected:
Parent Class Member As Public And Inherited As Public
//Access Modifiers In C++
#include <iostream>
using namespace std;
class Parent
{
public:
int x = 90;
Parent()
{
cout << "Parent Constructor." << endl;
}
};
class Child : protected Parent
{
public:
Child()
{
cout << x << endl;
cout << "Child Constructor." << endl;
}
};
int main()
{
Child C;
return 0;
}Output:
Parent Constructor.
90
Child Constructor.Parent Class Member As Private And Inherited As Public:
//Access Modifiers In C++
#include <iostream>
using namespace std;
class Parent
{
private:
int x = 90;
Parent()
{
cout << "Parent Constructor." << endl;
}
};
class Child : public Parent
{
public:
Child()
{
cout << x << endl;
cout << "Child Constructor." << endl;
}
};
int main()
{
Child C;
return 0;
}Output:
access_modifiers.cpp: In constructor 'Child::Child()':
access_modifiers.cpp:20:5: error: 'Parent::Parent()' is private within this context
{
^
access_modifiers.cpp:11:5: note: declared private here
Parent()
^~~~~~
access_modifiers.cpp:21:17: error: 'int Parent::x' is private within this context
cout << x << endl;
^
access_modifiers.cpp:10:13: note: declared private here
int x = 90;In the above output, if parent class members are private then they can’t access outside of class.
Parent Class Member As Protected And Inherited As Protected:
//Access Modifiers In C++
#include <iostream>
using namespace std;
class Parent
{
protected:
int x = 90;
Parent()
{
cout << "Parent Constructor." << endl;
}
};
class Child : protected Parent
{
public:
Child()
{
cout << x << endl;
cout << "Child Constructor." << endl;
}
};
int main()
{
Child C;
return 0;
}Output:
Parent Constructor.
90
Child Constructor.
