Base class pointer pointing to derived class object

Last Updated : 13 Apr, 2021

Pointers are the variable that stores the address of another variable is called a pointer.

The pointer of Base Class pointing different object of derived class:

Approach:

A derived class is a class which takes some properties from its base class.
It is true that a pointer of one class can point to other class, but classes must be a base and derived class, then it is possible.
To access the variable of the base class, base class pointer will be used.
So, a pointer is type of base class, and it can access all, public function and variables of base class since pointer is of base class, this is known as binding pointer.
In this pointer base class is owned by base class but points to derived class object.
Same works with derived class pointer, values is changed.

Below is the C++ program to illustrate the implementation of the base class pointer pointing to the derived class:

C++

// C++ program to illustrate the
// implementation of the base class
// pointer pointing to derived class
#include <iostream>
using namespace std;
 
// Base Class
class BaseClass {
public:
    int var_base;
 
    // Function to display the base
    // class members
    void display()
    {
        cout << "Displaying Base class"
             << " variable var_base: " << var_base << endl;
    }
};
 
// Class derived from the Base Class
class DerivedClass : public BaseClass {
public:
    int var_derived;
 
    // Function to display the base
    // and derived class members
    void display()
    {
        cout << "Displaying Base class"
             << "variable var_base: " << var_base << endl;
        cout << "Displaying Derived "
             << " class variable var_derived: "
             << var_derived << endl;
    }
};
 
// Driver Code
int main()
{
    // Pointer to base class
    BaseClass* base_class_pointer;
    BaseClass obj_base;
    DerivedClass obj_derived;
 
    // Pointing to derived class
    base_class_pointer = &obj_derived;
 
    base_class_pointer->var_base = 34;
 
    // Throw an error
    base_class_pointer->display();
 
    base_class_pointer->var_base = 3400;
    base_class_pointer->display();
 
    DerivedClass* derived_class_pointer;
    derived_class_pointer = &obj_derived;
    derived_class_pointer->var_base = 9448;
    derived_class_pointer->var_derived = 98;
    derived_class_pointer->display();
 
    return 0;
}

Output:

Displaying Base class variable var_base: 34
Displaying Base class variable var_base: 3400
Displaying Base classvariable var_base: 9448
Displaying Derived  class variable var_derived: 98

Conclusion:

A pointer to derived class is a pointer of base class pointing to derived class, but it will hold its aspect.
This pointer of base class will be able to temper functions and variables of its own class and can still point to derived class object.

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