Properties vs fields in C Sharp (C#) - Practice Questions

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of accessing property vs field

What is the output of this C# code?

C Sharp (C#)

class Person {
    public string Name = "Alice";
    private int age = 30;
    public int Age {
        get { return age; }
        set { age = value; }
    }
}

var p = new Person();
Console.WriteLine(p.Name);
Console.WriteLine(p.Age);

A null\n30

B Alice\n0

C null\n0

D Alice\n30

💡 Hint

Fields hold data directly. Properties can control access but here just return the field.

The field Name is set to "Alice". The property Age returns the private field age which is 30. So output is "Alice" and "30".

❓ Predict Output

intermediate

Effect of changing property setter

What is the output of this C# code?

C Sharp (C#)

class Counter {
    private int count = 0;
    public int Count {
        get { return count; }
        set { if (value > count) count = value; }
    }
}

var c = new Counter();
c.Count = 5;
c.Count = 3;
Console.WriteLine(c.Count);

A 3

B 5

C 0

D 8

💡 Hint

The setter only updates if the new value is greater than current.

First Count is set to 5. Then setting to 3 is ignored because 3 < 5. So final value is 5.

🔧 Debug

advanced

Why does this property cause a stack overflow?

What error does this code cause and why?

C Sharp (C#)

class Sample {
    private int value;
    public int Value {
        get { return value; }
        set { this.value = value; }
    }
}

var s = new Sample();
s.Value = 10;
Console.WriteLine(s.Value);

A StackOverflowException because property calls itself recursively

B NullReferenceException because value is null

C Compilation error due to missing semicolon

D Output is 10

💡 Hint

The property getter and setter use the property name inside themselves.

The getter calls Value which calls the getter again endlessly. Same for setter. This causes a stack overflow.

🧠 Conceptual

advanced

Difference between auto-property and field

Which statement correctly describes the difference between an auto-property and a field in C#?

A An auto-property has hidden backing field and can have logic in get/set; a field is just data storage.

B A field can have get/set logic; an auto-property cannot.

C An auto-property is slower because it uses reflection; a field is faster.

D A field can only be private; an auto-property can only be public.

💡 Hint

Think about what code the compiler generates for auto-properties.

Auto-properties create a hidden field automatically and allow get/set accessors. Fields are just variables without accessors.

❓ Predict Output

expert

Output of property with expression-bodied members

What is the output of this C# code?

C Sharp (C#)

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

var r = new Rectangle { Width = 4, Height = 5 };
Console.WriteLine(r.Area);

A Compilation error

B 9

C 20

D 0

💡 Hint

Expression-bodied properties calculate value on access.

The Area property returns Width * Height. With Width=4 and Height=5, Area is 20.