Function overriding in C++ - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a base class function that can be overridden.

C++

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

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

Arun

Bshow

Cprint

Ddisplay

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different function name that does not match the derived class function.

The function name display is used in the base class and will be overridden in the derived class.

2fill in blank

medium

Complete the code to override the base class function 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'

Aprint

Bdisplay

Cshow

Drun

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different function name or missing the override keyword.

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

3fill in blank

hard

Fix the error in the base class function declaration to allow overriding.

C++

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

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

Arun

Bshow

Cdisplay

Dprint

Attempts:

3 left

💡 Hint

Common Mistakes

Changing the function name so it does not match the derived class.

The base class function must be declared virtual to allow overriding, but here the blank is the function name which must be display to match derived class.

4fill in blank

hard

Fill both blanks to complete the derived class overriding the base class function.

C++

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

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

Avoid

Bint

Cdisplay

Dshow

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different return type or function name.

The function must have the same return type void and the same name display as in the base class to override it.

5fill in blank

hard

Fill all three blanks to call the overridden function through a base class pointer.

C++

Base* ptr = new Derived();
ptr->[1]();
delete [2];
[3] = nullptr;

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

Aptr

Bdisplay

DbasePtr

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong pointer names or function names.

We call the overridden function display through the base class pointer ptr, then delete and nullify the pointer.