Computed properties in C Sharp (C#) - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of computed property in C#

What is the output of this C# program that uses a computed property?

C Sharp (C#)

public class Rectangle {
    public int Width { get; set; }
    public int Height { get; set; }
    public int Area => Width * Height;
}

class Program {
    static void Main() {
        var rect = new Rectangle { Width = 4, Height = 5 };
        System.Console.WriteLine(rect.Area);
    }
}

A 20

B 9

C 0

D Compilation error

💡 Hint

The Area property calculates Width multiplied by Height.

The computed property Area returns Width * Height, which is 4 * 5 = 20.

❓ Predict Output

intermediate

Computed property with backing field

What will be the output of this C# code using a computed property with a backing field?

C Sharp (C#)

public class Circle {
    private double radius;
    public double Radius {
        get => radius;
        set => radius = value;
    }
    public double Diameter => 2 * Radius;
}

class Program {
    static void Main() {
        var c = new Circle { Radius = 3 };
        System.Console.WriteLine(c.Diameter);
    }
}

A 3

B 9

C Runtime error

D 6

💡 Hint

Diameter is twice the radius.

Diameter returns 2 times Radius, so 2 * 3 = 6.

❓ Predict Output

advanced

Computed property with conditional logic

What is the output of this C# program with a computed property that uses conditional logic?

C Sharp (C#)

public class Temperature {
    public double Celsius { get; set; }
    public string State => Celsius >= 100 ? "Gas" : Celsius <= 0 ? "Solid" : "Liquid";
}

class Program {
    static void Main() {
        var t = new Temperature { Celsius = 50 };
        System.Console.WriteLine(t.State);
    }
}

A "Solid"

B "Gas"

C "Liquid"

D Compilation error

💡 Hint

Check the temperature ranges for state.

Since 50 is between 0 and 100, State returns "Liquid".

❓ Predict Output

advanced

Computed property with side effect

What will be printed by this C# program where a computed property has a side effect?

C Sharp (C#)

public class Counter {
    private int count = 0;
    public int Count {
        get {
            count++;
            return count;
        }
    }
}

class Program {
    static void Main() {
        var c = new Counter();
        System.Console.WriteLine(c.Count);
        System.Console.WriteLine(c.Count);
    }
}

A 1\n2

B Compilation error

C 1\n1

D 0\n1

💡 Hint

Each access to Count increments count before returning.

The first call returns 1, the second returns 2 because count increments each time.

🧠 Conceptual

expert

Understanding computed properties behavior

Which statement about computed properties in C# is TRUE?

A Computed properties always cache their result after first calculation.

B Computed properties execute their code every time they are accessed.

C Computed properties cannot use conditional logic.

D Computed properties can store values internally without a backing field.

💡 Hint

Think about when the code inside a computed property runs.

Computed properties run their code each time they are accessed; they do not store values unless explicitly coded.