Method overriding in C++ - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a virtual function in the base class.

C++

class Base {
public:
    virtual void [1]() {
        std::cout << "Base function" << std::endl;
    }
};

Drag options to blanks, or click blank then click option'

Aoutput

Bdisplay

Cprint

Dshow

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different method name than the one overridden in the derived class.

The method name display is used as the virtual function in the base class.

2fill in blank

medium

Complete the code to override the base class method in the derived class.

C++

class Derived : public Base {
public:
    void [1]() override {
        std::cout << "Derived function" << std::endl;
    }
};

Drag options to blanks, or click blank then click option'

Adisplay

Bprint

Cshow

Doutput

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different method name, which does not override the base method.

The derived class overrides the display method from the base class.

3fill in blank

hard

Fix the error in the code by completing the method declaration to enable overriding.

C++

class Base {
public:
    [1] void display() {
        std::cout << "Base function" << std::endl;
    }
};

Drag options to blanks, or click blank then click option'

Adisplay

Bvirtual void display

Coverride display

Dvirtual

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting the virtual keyword, which disables overriding.

The method must be declared with the virtual keyword to allow overriding.

4fill in blank

hard

Fill both blanks to correctly override the base class method and call it from the derived class.

C++

class Derived : public Base {
public:
    void [1]() override {
        Base::[2]();
        std::cout << "Derived override" << std::endl;
    }
};

Drag options to blanks, or click blank then click option'

Adisplay

Bshow

Dprint

Attempts:

3 left

💡 Hint

Common Mistakes

Using different method names that do not match the base class.

The derived class overrides display and calls the base class display method.

5fill in blank

hard

Fill all three blanks to create a base class with a virtual method, override it in the derived class, and call the method via a base pointer.

C++

class Base {
public:
    [1] void display() {
        std::cout << "Base display" << std::endl;
    }
};

class Derived : public Base {
public:
    void [2]() override {
        std::cout << "Derived display" << std::endl;
    }
};

int main() {
    Base* ptr = new Derived();
    ptr->[3]();
    delete ptr;
    return 0;
}

Drag options to blanks, or click blank then click option'

Avirtual

Bdisplay

Doverride

Attempts:

3 left

💡 Hint

Common Mistakes

Not marking the base method as virtual, so overriding does not work.

Forgetting the override keyword in the derived class.

Calling a wrong method name via pointer.

The base class method is declared virtual. The derived class method uses override. The method called via pointer is display.