Base and derived classes in C++ - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a base class named Animal.

C++

class [1] {
public:
    void speak() {
        std::cout << "Animal sound" << std::endl;
    }
};

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

ADog

BAnimal

CCat

DBird

Attempts:

3 left

💡 Hint

Common Mistakes

Using a derived class name instead of the base class name.

Misspelling the class name.

The base class is named Animal. This is the class from which others can inherit.

2fill in blank

medium

Complete the code to declare a derived class Dog that inherits from Animal.

C++

class Dog : public [1] {
public:
    void speak() {
        std::cout << "Woof!" << std::endl;
    }
};

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

AAnimal

BCat

CBird

DFish

Attempts:

3 left

💡 Hint

Common Mistakes

Using a class name that is not the base class.

Forgetting the public keyword.

The derived class Dog inherits from the base class Animal using public inheritance.

3fill in blank

hard

Fix the error in the code to call the base class speak() method inside the derived class Dog's speak() method.

C++

class Dog : public Animal {
public:
    void speak() {
        [1]::speak();
        std::cout << "Woof!" << std::endl;
    }
};

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

ADog

BBase

CAnimal

DParent

Attempts:

3 left

💡 Hint

Common Mistakes

Using the derived class name instead of the base class name.

Using incorrect class names like Base or Parent.

To call the base class method, use the base class name Animal followed by the scope resolution operator.

4fill in blank

hard

Fill both blanks to create a constructor in the derived class Cat that calls the base class constructor with a name parameter.

C++

class Cat : public Animal {
public:
    Cat(std::string [1]) : [2]([1]) {}
};

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Aname

BAnimal

CDog

DCat

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for the parameter and argument.

Calling the wrong class constructor.

The constructor parameter is name. The base class constructor Animal is called with this parameter.

5fill in blank

hard

Fill all three blanks to override the speak() method in the derived class Bird and call the base class speak() method.

C++

class Bird : public [1] {
public:
    void speak() override {
        [2]::[3]();
        std::cout << "Tweet!" << std::endl;
    }
};

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

AAnimal

BBird

Cspeak

DDog

Attempts:

3 left

💡 Hint

Common Mistakes

Using the derived class name instead of the base class name.

Using incorrect method names.

The derived class Bird inherits from Animal. To call the base class method, use Animal::speak().