Record inheritance in C Sharp (C#) - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of record inheritance with positional parameters

What is the output of this C# code using record inheritance with positional parameters?

C Sharp (C#)

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);

A Employee { Name = Alice, Age = 30, Position = Developer }

B Person { Name = Alice, Age = 30 }

C Person { Name = Alice, Age = 30, Position = Developer }

D Employee { Name = Alice, Position = Developer }

💡 Hint

Remember that the derived record includes all properties from base and derived types in its ToString output.

In C#, a record's ToString method automatically includes all properties declared in the record and its base records. Here, Employee inherits from Person and adds Position, so the output shows all three properties.

❓ Predict Output

intermediate

Value equality in record inheritance

What is the output of this C# code comparing two records with inheritance?

C Sharp (C#)

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

var emp1 = new Employee("Bob", 25, "Tester");
var emp2 = new Employee("Bob", 25, "Tester");
Console.WriteLine(emp1 == emp2);

A False

B Compilation error

C Runtime exception

D True

💡 Hint

Records compare by value, including all properties from base and derived records.

Records in C# implement value equality by default, comparing all properties including those inherited. Since emp1 and emp2 have identical values, the equality operator returns True.

❓ Predict Output

advanced

Output of record inheritance with overridden ToString

What is the output of this C# code where a derived record overrides ToString?

C Sharp (C#)

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

var emp = new Employee("Carol", 28, "Manager");
Console.WriteLine(emp);

A Compilation error due to ToString override

B Person: Carol, 28

C Person { Name = Carol, Age = 28 }

D Employee { Name = Carol, Age = 28, Position = Manager }

💡 Hint

The derived record inherits the overridden ToString from the base record unless it overrides it again.

Since Employee does not override ToString, it uses the base Person's override. So printing emp calls Person's ToString, producing 'Person: Carol, 28'.

❓ Predict Output

advanced

Deconstruction behavior in record inheritance

What is the output of this C# code demonstrating deconstruction in record inheritance?

C Sharp (C#)

public record Person(string Name, int Age)
{
    public void Deconstruct(out string name, out int age) => (name, age) = (Name, Age);
}
public record Employee(string Name, int Age, string Position) : Person(Name, Age)
{
    public void Deconstruct(out string name, out int age, out string position) => (name, age, position) = (Name, Age, Position);
}

var emp = new Employee("Dave", 40, "Lead");
var (n, a, p) = emp;
Console.WriteLine($"{n}, {a}, {p}");

A Dave, 40, Lead

B Dave, 40

C Compilation error: Deconstruct mismatch

D Runtime error: Deconstruct failed

💡 Hint

The derived record defines a Deconstruct method with three out parameters matching its properties.

The Employee record defines a Deconstruct method with three parameters, so deconstruction extracts all three values correctly. The output prints all three values separated by commas.

🧠 Conceptual

expert

Understanding record inheritance and immutability

Which statement about record inheritance and immutability in C# is correct?

A Derived records must override all base record properties to maintain immutability.

B Records are always fully immutable, so derived records cannot add mutable properties.

C Derived records can add mutable properties without affecting the base record's immutability.

D Records do not support inheritance to preserve immutability.

💡 Hint

Think about how records handle properties and immutability in inheritance.

Records provide immutability by default for properties declared with init-only setters. Derived records can add new properties, including mutable ones, but this does not change the base record's properties. So immutability applies per property, not enforced globally.