How constructor chaining works in C Sharp (C#) - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to call the default constructor from the parameterized constructor.

C Sharp (C#)

public class Car {
    public Car() {
        Console.WriteLine("Default constructor called");
    }

    public Car(string model) : [1] {
        Console.WriteLine($"Car model: {model}");
    }
}

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Athis()

Bbase()

CCar()

Dsuper()

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'base()' instead of 'this()' to call the same class constructor.

Trying to call constructor like a method without 'this()'.

In C#, this() calls another constructor in the same class, enabling constructor chaining.

2fill in blank

medium

Complete the code to chain constructors so the parameterless constructor calls the parameterized one.

C Sharp (C#)

public class Book {
    public Book(string title) {
        Console.WriteLine($"Title: {title}");
    }

    public Book() : [1] {
        Console.WriteLine("No title provided");
    }
}

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Athis("Unknown")

Bbase()

CBook()

Dthis()

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'base()' which calls the base class constructor instead.

Calling 'this()' without arguments when the parameterized constructor needs one.

The parameterless constructor calls the parameterized one with a default value using this("Unknown").

3fill in blank

hard

Fix the error in constructor chaining by completing the code.

C Sharp (C#)

public class Person {
    public Person(string name) {
        Console.WriteLine($"Name: {name}");
    }

    public Person() : [1] {
        Console.WriteLine("No name given");
    }
}

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Athis()

BPerson()

Cbase()

Dthis(null)

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'this()' without arguments when the constructor needs one.

Using 'base()' which calls the base class constructor instead.

The parameterless constructor must call the parameterized one with a string argument, so this(null) is correct.

4fill in blank

hard

Fill both blanks to chain constructors correctly and print the age.

C Sharp (C#)

public class Animal {
    public Animal(string species, int age) {
        Console.WriteLine($"Species: {species}, Age: {age}");
    }

    public Animal(string species) : [1] {
        Console.WriteLine($"Species only: {species}");
    }

    public Animal() : [2] {
        Console.WriteLine("No details provided");
    }
}

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Athis(species, 0)

Bthis()

Cthis("Unknown", 0)

Dbase()

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'base()' instead of 'this()' for chaining.

Not passing the required arguments in constructor chaining.

The constructor with one parameter calls the two-parameter constructor with age 0 using this(species, 0). The parameterless constructor calls the two-parameter constructor with "Unknown" and age 0 using this("Unknown", 0).

5fill in blank

hard

Fill all three blanks to chain constructors and initialize all fields.

C Sharp (C#)

public class Employee {
    public string Name;
    public int Id;
    public string Department;

    public Employee(string name, int id, string department) {
        Name = name;
        Id = id;
        Department = department;
        Console.WriteLine($"Name: {Name}, Id: {Id}, Department: {Department}");
    }

    public Employee(string name, int id) : [1] {
        Console.WriteLine("Department set to General");
    }

    public Employee(string name) : [2] {
        Console.WriteLine("Id set to 0 and Department to General");
    }

    public Employee() : [3] {
        Console.WriteLine("Default employee created");
    }
}

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Athis(name, id, "General")

Bthis(name, 0, "General")

Cthis("Unknown", 0, "General")

Dbase()

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'base()' instead of 'this()' for chaining.

Not providing all required arguments in chained constructors.

Each constructor calls the three-parameter constructor with default values to chain initialization properly: the two-parameter constructor calls the three-parameter one with "General" department using this(name, id, "General"), the one-parameter constructor calls the three-parameter one with id 0 and "General" using this(name, 0, "General"), and the parameterless constructor calls the three-parameter one with "Unknown", 0, and "General" using this("Unknown", 0, "General").