Why constructors are needed in C++ - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a constructor for the class.

C++

class Car {
public:
    [1]() {
        speed = 0;
    }
private:
    int speed;
};

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

Acar

BCar

Cvoid Car

Dint Car

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase 'car' instead of 'Car'.

Adding a return type like 'void' or 'int' to the constructor.

The constructor must have the same name as the class, which is Car.

2fill in blank

medium

Complete the constructor to initialize the member variable 'speed' with the given value.

C++

class Car {
public:
    Car(int s) {
        [1] = s;
    }
private:
    int speed;
};

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Aspeed

Bs

CCar::speed

Dthis->speed

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning to the parameter s instead of the member variable.

Using just 'speed' without this-> which can cause confusion.

Using this->speed clearly refers to the member variable speed of the object.

3fill in blank

hard

Fix the error in the constructor declaration to properly initialize 'speed'.

C++

class Car {
public:
    Car(int s) : [1](s) {}
private:
    int speed;
};

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Aspeed

Bs

Cthis->speed

DCar::speed

Attempts:

3 left

💡 Hint

Common Mistakes

Using the parameter name 's' instead of the member variable 'speed' in the initializer list.

Using 'this->speed' which is not allowed in initializer lists.

The member initializer list must use the member variable name speed to initialize it.

4fill in blank

hard

Fill both blanks to create a constructor that sets 'speed' and 'color' with given values.

C++

class Car {
public:
    Car(int s, std::string c) : [1](s), [2](c) {}
private:
    int speed;
    std::string color;
};

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Aspeed

Bs

Ccolor

Dc

Attempts:

3 left

💡 Hint

Common Mistakes

Using parameter names instead of member variable names in the initializer list.

Mixing up the order of initialization.

The initializer list must use member variable names speed and color to initialize them.

5fill in blank

hard

Fill all three blanks to create a constructor that initializes 'speed', 'color', and 'model'.

C++

class Car {
public:
    Car(int s, std::string c, std::string m) : [1](s), [2](c), [3](m) {}
private:
    int speed;
    std::string color;
    std::string model;
};

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

Aspeed

Bcolor

Cmodel

Dm

Attempts:

3 left

💡 Hint

Common Mistakes

Using parameter names instead of member variable names in the initializer list.

Forgetting to initialize one of the member variables.

The constructor's initializer list must use the member variable names speed, color, and model to initialize them.