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

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of a simple record declaration

What is the output of this C# program using a record declaration?

C Sharp (C#)

public record Person(string Name, int Age);

class Program {
    static void Main() {
        var p = new Person("Alice", 30);
        System.Console.WriteLine(p);
    }
}

A Name: Alice, Age: 30

B Alice 30

C Person(Alice, 30)

D Person { Name = Alice, Age = 30 }

💡 Hint

Records override ToString() to show property names and values.

In C#, records automatically generate a ToString() method that outputs the record type name and its properties with their values in the format: TypeName { Property1 = value1, Property2 = value2 }.

❓ Predict Output

intermediate

Output of record with inheritance

What is the output of this C# program with record inheritance?

C Sharp (C#)

public record Animal(string Name);
public record Dog(string Name, string Breed) : Animal(Name);

class Program {
    static void Main() {
        var d = new Dog("Buddy", "Beagle");
        System.Console.WriteLine(d);
    }
}

A Dog { Name = Buddy, Breed = Beagle }

B Animal { Name = Buddy }

C Dog(Buddy, Beagle)

D Buddy Beagle

💡 Hint

Derived records include all properties in ToString output.

The derived record Dog inherits from Animal and adds Breed. The ToString() method shows all properties from both records.

🔧 Debug

advanced

Identify the syntax error in record declaration

Which option contains a syntax error in the record declaration?

A public record Car(string Make; string Model);

B public record Car(string Make, string Model);

C public record Car(string Make, string Model) {}

D public record Car { string Make; string Model; }

💡 Hint

Check the separator between parameters in the record declaration.

In C#, record positional parameters must be separated by commas, not semicolons. Option A uses semicolons, causing a syntax error.

❓ Predict Output

advanced

Output of record with custom ToString override

What is the output of this C# program with a record that overrides ToString()?

C Sharp (C#)

public record Point(int X, int Y) {
    public override string ToString() => $"({X}, {Y})";
}

class Program {
    static void Main() {
        var pt = new Point(3, 4);
        System.Console.WriteLine(pt);
    }
}

A 3, 4

B Point { X = 3, Y = 4 }

C (3, 4)

D Point(3, 4)

💡 Hint

The record overrides ToString to return a custom string.

The overridden ToString() method returns the coordinates in parentheses, so the output is (3, 4).

🧠 Conceptual

expert

Number of properties in a record with inheritance

Given these record declarations, how many properties does the record 'Employee' have?

C Sharp (C#)

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

A 2

B 3

C 4

D 1

💡 Hint

Count all positional parameters from base and derived records.

Employee inherits Name and Age from Person and adds Position, so it has 3 properties total.