Record inheritance in C Sharp (C#) - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a record named Person.

C Sharp (C#)

public record [1](string Name, int Age);

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

Ainterface

Bclass

Cstruct

DPerson

Attempts:

3 left

💡 Hint

Common Mistakes

Using class or struct instead of record.

Forgetting to name the record.

The keyword record is used to declare a record type. Here, Person is the record's name.

2fill in blank

medium

Complete the code to make Employee inherit from Person record.

C Sharp (C#)

public record Employee(string Name, int Age, string Position) : [1](Name, Age);

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

Aobject

BEmployee

CPerson

Drecord

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong base record name.

Omitting the base constructor call.

The Employee record inherits from Person using the colon : followed by the base record name and parameters.

3fill in blank

hard

Fix the error in the code to correctly override the ToString method in the Employee record.

C Sharp (C#)

public record Employee(string Name, int Age) : Person(Name, Age)
{
    public override string [1]() => $"Employee: {Name}, {Age}";
}

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

AToString

BToStr

CtoString

DPrint

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase toString which does not exist in C#.

Using incorrect method names like ToStr or Print.

The method to override for string representation is ToString with capital T and S.

4fill in blank

hard

Fill both blanks to create a derived record Manager that inherits from Employee and adds a Department property.

C Sharp (C#)

public record Manager(string Name, int Age, string Position, string [1]) : Employee(Name, Age, Position)
{
    public string [2] { get; init; } = [1];
}

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

ADepartment

BPosition

CAge

DName

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for the property and initializer.

Using base record property names instead of the new property.

The Manager record adds a Department property and passes other parameters to the Employee base record.

5fill in blank

hard

Fill all three blanks to override the PrintDetails method in Manager, calling base method and adding department info.

C Sharp (C#)

public record Manager(string Name, int Age, string Position, string Department) : Employee(Name, Age, Position)
{
    public void PrintDetails()
    {
        base.[1]();
        Console.WriteLine($"Department: [2]");
        Console.WriteLine($"Position: [3]");
    }
}

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

APrintDetails

BDepartment

CPosition

DToString

Attempts:

3 left

💡 Hint

Common Mistakes

Calling a wrong base method name.

Using incorrect property names in the output.

The PrintDetails method calls the base method, then prints Department and Position properties.

Practice

1.

What does record inheritance in C# allow you to do?

easy

A. Delete properties from the base record in the derived record

B. Change the data type of existing properties in a record

C. Convert a record into a class automatically

D. Create a new record that extends an existing record with additional properties

Solution

1. Step 1: Understand record inheritance purpose

   Record inheritance lets you build new records based on existing ones, adding new properties while keeping the base properties.

2. Step 2: Analyze options

   Only Create a new record that extends an existing record with additional properties correctly describes extending an existing record with new properties. Options A, B, and D describe actions not supported by record inheritance.

3. Final Answer:

   Create a new record that extends an existing record with additional properties -> Option D

4. Quick Check:

   Record inheritance = extend with new properties [OK]

Hint: Inheritance means adding new features, not removing or changing [OK]

Common Mistakes:

• Thinking inheritance changes base properties
• Confusing records with classes
• Assuming inheritance deletes base properties

2.

Which of the following is the correct syntax to inherit a record Person in C#?

public record Person(string Name, int Age);

easy

A. public record Employee(string Name, int Age, string Position) : Person(Name, Age);

B. public record Employee : Person(string Name, int Age, string Position);

C. public record Employee(string Name, int Age, string Position) inherits Person(Name, Age);

D. public record Employee(string Name, int Age, string Position) extends Person(Name, Age);

Solution

1. Step 1: Recall record inheritance syntax

   In C#, a derived record uses colon : to inherit and passes base parameters in parentheses after the base name.

2. Step 2: Check each option

   public record Employee(string Name, int Age, string Position) : Person(Name, Age); correctly uses colon and passes base parameters. Options B, C, and D use incorrect keywords or syntax.

3. Final Answer:

   public record Employee(string Name, int Age, string Position) : Person(Name, Age); -> Option A

4. Quick Check:

   Use ':' and pass base params in parentheses [OK]

Hint: Use ':' and pass base parameters in parentheses [OK]

Common Mistakes:

• Using 'inherits' or 'extends' keywords
• Not passing base parameters
• Placing base parameters incorrectly

3.

What will be the output of this code?

public record Person(string Name, int Age);
public record Employee(string Name, int Age, string Position) : Person(Name, Age);

var emp = new Employee("Alice", 30, "Developer");
Console.WriteLine(emp.Name + ", " + emp.Age + ", " + emp.Position);

medium

A. Alice, 30

B. Developer, 30, Alice

C. Alice, 30, Developer

D. Compilation error

Solution

1. Step 1: Understand record inheritance and properties

   The Employee record inherits Name and Age from Person and adds Position. Creating Employee sets all three properties.

2. Step 2: Analyze output statement

   The code prints emp.Name, emp.Age, and emp.Position separated by commas, so output is "Alice, 30, Developer".

3. Final Answer:

   Alice, 30, Developer -> Option C

4. Quick Check:

   Inherited + new properties print correctly [OK]

Hint: Inherited properties are accessible like own properties [OK]

Common Mistakes:

• Assuming only base or only derived properties print
• Expecting compilation error due to inheritance
• Mixing property order in output

4.

Identify the error in this record inheritance code:

public record Person(string Name, int Age);
public record Employee(string Name, int Age, string Position) : Person;

var emp = new Employee("Bob", 25, "Tester");

medium

A. Employee record cannot have more than two properties

B. Missing base constructor arguments in Employee inheritance

C. Position property must be in base record

D. Cannot inherit from a record

Solution

1. Step 1: Check inheritance syntax

   Employee inherits Person but does not pass required base constructor arguments (Name, Age) after Person.

2. Step 2: Identify correct fix

   Base constructor arguments must be passed like : Person(Name, Age). Omitting them causes a compilation error.

3. Final Answer:

   Missing base constructor arguments in Employee inheritance -> Option B

4. Quick Check:

   Base constructor args required after ':' [OK]

Hint: Always pass base constructor parameters after ':' [OK]

Common Mistakes:

• Forgetting to pass base parameters
• Thinking inheritance disallows extra properties
• Assuming records can't inherit

5.

You have a base record Vehicle(string Make, string Model). You want to create a derived record Car that adds int Doors and overrides the ToString() method to show all info. Which is the correct way to do this?

hard

A. public record Car(string Make, string Model, int Doors) : Vehicle(Make, Model) { public override string ToString() => $"{Make} {Model} with {Doors} doors"; }

B. public record Car : Vehicle { public int Doors; public override string ToString() => $"{Make} {Model} with {Doors} doors"; }

C. public record Car(string Make, string Model, int Doors) inherits Vehicle { public override string ToString() => $"{Make} {Model} with {Doors} doors"; }

D. public record Car(string Make, string Model, int Doors) extends Vehicle(Make, Model) { public override string ToString() => $"{Make} {Model} with {Doors} doors"; }

Solution

1. Step 1: Use correct inheritance syntax with parameters

   Derived record Car must inherit Vehicle using colon and pass Make and Model parameters: : Vehicle(Make, Model).

2. Step 2: Override ToString() properly

   Inside Car, override ToString() with the correct string interpolation including Doors property.

3. Step 3: Check options

   public record Car(string Make, string Model, int Doors) : Vehicle(Make, Model) { public override string ToString() => $"{Make} {Model} with {Doors} doors"; } uses correct syntax and override. Options B, C, and D use invalid keywords or omit constructor parameters.

4. Final Answer:

   public record Car(string Make, string Model, int Doors) : Vehicle(Make, Model) { public override string ToString() => $"{Make} {Model} with {Doors} doors"; } -> Option A

5. Quick Check:

   Use ':' with base params and override method inside record [OK]

Hint: Use ':' with base params and override inside record body [OK]

Common Mistakes:

• Using 'inherits' or 'extends' keywords
• Not passing base constructor parameters
• Trying to add fields instead of properties