Why inheritance is used in C++ - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

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

C++

class Dog : public [1] {
};

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AAnimal

BDog

CCat

DVehicle

Attempts:

3 left

💡 Hint

Common Mistakes

Using the same class name for inheritance (Dog inherits Dog).

Using unrelated class names like Vehicle.

Inheritance means a class (Dog) gets properties and behaviors from another class (Animal). So Dog inherits from Animal.

2fill in blank

medium

Complete the code to call the base class constructor from the derived class Car.

C++

class Vehicle {
public:
    Vehicle(int wheels) {}
};

class Car : public Vehicle {
public:
    Car() : [1](4) {}
};

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ACar

Bint

Cwheels

DVehicle

Attempts:

3 left

💡 Hint

Common Mistakes

Calling the derived class constructor inside itself.

Using variable names instead of class names.

The derived class constructor calls the base class constructor by using the base class name (Vehicle) followed by arguments.

3fill in blank

hard

Fix the error in the code to correctly override the makeSound method in the derived class Cat.

C++

class Animal {
public:
    virtual void makeSound() {
        std::cout << "Some sound" << std::endl;
    }
};

class Cat : public Animal {
public:
    [1] void makeSound() override {
        std::cout << "Meow" << std::endl;
    }
};

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Aoverride

Bvirtual

Cvoid

Dpublic

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting the return type.

Using 'override' keyword without proper syntax.

To override a virtual function, the derived class method should also be declared virtual (optional but good practice) and match the signature. The keyword 'virtual' before the method helps clarity.

4fill in blank

hard

Fill both blanks to create a derived class Bird that inherits publicly from Animal and overrides the fly method.

C++

class Animal {
public:
    virtual void fly() {
        std::cout << "Cannot fly" << std::endl;
    }
};

class Bird : [1] [2] {
public:
    void fly() override {
        std::cout << "Flying high" << std::endl;
    }
};

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Apublic

Bprivate

CAnimal

DBird

Attempts:

3 left

💡 Hint

Common Mistakes

Using private inheritance which hides base class methods.

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

The class Bird inherits publicly from Animal, so use 'public Animal'. This allows Bird to override the fly method.

5fill in blank

hard

Fill all three blanks to create a dictionary-like map of animal names to their sound lengths, filtering only those with sound length greater than 3.

C++

std::map<std::string, int> soundLengths = {
    {"dog", 3},
    {"elephant", 8},
    {"cat", 3},
    {"bird", 4}
};

std::map<std::string, int> filtered;
for (const auto& [1] : soundLengths) {
    if ([2].second [3] 3) {
        filtered.insert([2]);
    }
}

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

Aentry

C>

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names inconsistently.

Using < instead of > causing wrong filtering.

We use a loop variable 'entry' to iterate over the map. We check if entry.second (the sound length) is greater than 3, then insert it into filtered.