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

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of auto-implemented property usage

What is the output of this C# code snippet using auto-implemented properties?

C Sharp (C#)

public class Person {
    public string Name { get; set; }
}

var p = new Person();
p.Name = "Alice";
System.Console.WriteLine(p.Name);

A Name

B null

C Alice

D Compilation error

💡 Hint

Auto-implemented properties automatically create a hidden field to store the value.

The property Name is auto-implemented with get and set. Assigning "Alice" to p.Name stores it, so printing p.Name outputs "Alice".

🧠 Conceptual

intermediate

Default value of auto-implemented property

What is the default value of an auto-implemented property of type int in C# if not explicitly set?

A null

B 0

C 1

D Compilation error

💡 Hint

Consider the default value of value types in C#.

Auto-implemented properties use backing fields. For int, the default value is 0 if not set.

🔧 Debug

advanced

Identify the error in auto-implemented property declaration

What error does this code produce? public class Car { public string Model { get; } } var c = new Car(); c.Model = "Tesla";

C Sharp (C#)

public class Car {
    public string Model { get; }
}

var c = new Car();
c.Model = "Tesla";

A CS0200: Property or indexer 'Car.Model' cannot be assigned to -- it is read only

B CS0120: An object reference is required for the non-static field, method, or property

C No error, outputs Tesla

D CS0501: 'Car.Model.set' must declare a body because it is not marked abstract or extern

💡 Hint

Check if the property has a setter.

The property Model has only a getter, so assigning to it causes a compile-time error CS0200.

📝 Syntax

advanced

Correct syntax for auto-implemented property with private setter

Which option correctly declares an auto-implemented property named Age with a public getter and a private setter?

A public int Age { get private; set; }

B public int Age { private get; set; }

C public int Age { get; set; private }

D public int Age { get; private set; }

💡 Hint

The access modifier for the setter goes before 'set;' inside the property.

Option D uses the correct syntax for a private setter with a public getter.

🚀 Application

expert

Number of items in dictionary from auto-implemented property usage

Consider this C# code: public class Item { public int Id { get; set; } } var items = new List { new Item { Id = 1 }, new Item { Id = 2 }, new Item { Id = 1 } }; var dict = items.ToDictionary(i => i.Id); How many items does dict contain after execution?

C Sharp (C#)

public class Item {
    public int Id { get; set; }
}

var items = new List<Item> {
    new Item { Id = 1 },
    new Item { Id = 2 },
    new Item { Id = 1 }
};

var dict = items.ToDictionary(i => i.Id);

System.Console.WriteLine(dict.Count);

A Runtime exception

B 3

C 1

D 2

💡 Hint

Check if keys in a dictionary must be unique.

The ToDictionary method throws an exception because there are duplicate keys (Id=1) in the list.