Read-only and write-only properties in C Sharp (C#) - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to make the property read-only.

C Sharp (C#)

public class Person {
    private string name;
    public string Name {
        get { return [1]; }
    }
}

Drag options to blanks, or click blank then click option'

Aname

BName

Cthis.name

Dnull

Attempts:

3 left

💡 Hint

Common Mistakes

Returning the property itself causes infinite recursion.

Returning null does not provide the stored value.

The get accessor returns the private field name, making the property read-only.

2fill in blank

medium

Complete the code to make the property write-only.

C Sharp (C#)

public class Account {
    private decimal balance;
    public decimal Balance {
        set { [1] = value; }
    }
}

Drag options to blanks, or click blank then click option'

ABalance

Bthis.Balance

Cvalue

Dbalance

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning to the property itself causes infinite recursion.

Assigning to 'value' is invalid.

The set accessor assigns the incoming value to the private field balance, making the property write-only.

3fill in blank

hard

Fix the error in the read-only property to avoid infinite recursion.

C Sharp (C#)

public class Product {
    private int stock;
    public int Stock {
        get { return [1]; }
    }
}

Drag options to blanks, or click blank then click option'

A0

Bstock

Cthis.Stock

DStock

Attempts:

3 left

💡 Hint

Common Mistakes

Returning the property itself causes infinite recursion.

Returning a constant like 0 does not reflect the actual value.

Returning the private field stock avoids infinite recursion caused by returning the property itself.

4fill in blank

hard

Fill both blanks to create a read-only property with a private setter.

C Sharp (C#)

public class Employee {
    public int Id { get; [1] }
    public string Name { get; [2] }
}

Drag options to blanks, or click blank then click option'

Aprivate set

Bset

Cprivate get

Dpublic set

Attempts:

3 left

💡 Hint

Common Mistakes

Using public set makes the property writable from outside.

Using private get is invalid for read-only properties.

Using private set allows the property to be set only inside the class, making it effectively read-only from outside.

5fill in blank

hard

Fill all three blanks to create a write-only property with a private getter.

C Sharp (C#)

public class Secret {
    private string data;
    public string Data {
        [1] { return data; }
        [2] { data = value; }
    }
    private string GetData() {
        return [3];
    }
}

Drag options to blanks, or click blank then click option'

Aprivate get

Bset

Cdata

Dget

Attempts:

3 left

💡 Hint

Common Mistakes

Using public get makes the property readable from outside.

Returning the property itself causes recursion.

The property has a private getter and a public setter, making it write-only from outside. The private method returns the private field data.

Practice

1.

Which statement correctly describes a read-only property in C#?

easy

A. It has only a set accessor and no get accessor.

B. It has only a get accessor and no set accessor.

C. It has both get and set accessors.

D. It has no accessors at all.

Solution

1. Step 1: Understand property accessors

   A property with only a get accessor allows reading but not writing.

2. Step 2: Identify read-only property

   Read-only properties have no set accessor, so they cannot be assigned a value.

3. Final Answer:

   It has only a get accessor and no set accessor. -> Option B

4. Quick Check:

   Read-only = get only [OK]

Hint: Read-only means only get accessor present [OK]

Common Mistakes:

• Confusing read-only with write-only properties
• Thinking both get and set are needed for read-only
• Assuming no accessors means read-only

2.

Which of the following is the correct syntax for a write-only property named Password in C#?

public string Password { ? }

easy

A. set { _password = value; }

B. get { return _password; }

C. get; set;

D. private get; public set;

Solution

1. Step 1: Identify write-only property syntax

   A write-only property has only a set accessor to allow writing but no reading.

2. Step 2: Match syntax to write-only

   set { _password = value; } shows only a set accessor with assignment, which is correct for write-only.

3. Final Answer:

   set { _password = value; } -> Option A

4. Quick Check:

   Write-only = set only [OK]

Hint: Write-only means only set accessor present [OK]

Common Mistakes:

• Using get accessor in write-only property
• Using both get and set for write-only
• Incorrect accessor visibility modifiers

3.

What will be the output of the following C# code?

class User {
    private string _name = "Alice";
    public string Name { get { return _name; } }
}

var user = new User();
Console.WriteLine(user.Name);

medium

A. Compilation error

B. null

C. Runtime error

D. Alice

Solution

1. Step 1: Analyze the property

   The Name property is read-only with a get accessor returning "Alice".

2. Step 2: Check output of Console.WriteLine

   Calling user.Name returns "Alice", so it prints "Alice".

3. Final Answer:

   Alice -> Option D

4. Quick Check:

   Read-only property returns stored value [OK]

Hint: Read-only property returns stored value when accessed [OK]

Common Mistakes:

• Expecting a compilation error due to missing set
• Thinking write-only properties can be read
• Confusing private field with property access

4.

Identify the error in this C# code snippet:

class Account {
    private string _pin;
    public string Pin {
        get { return _pin; }
        set { _pin = value; }
    }
}

var acc = new Account();
acc.Pin = "1234";
Console.WriteLine(acc.Pin);

The goal is to make Pin write-only.

medium

A. The private field _pin should be public.

B. The set accessor should return a value.

C. The property has both get and set accessors, so it is not write-only.

D. The property should be static.

Solution

1. Step 1: Check property accessors

   The property has both get and set accessors, allowing reading and writing.

2. Step 2: Understand write-only requirement

   Write-only properties must have only a set accessor and no get accessor.

3. Final Answer:

   The property has both get and set accessors, so it is not write-only. -> Option C

4. Quick Check:

   Write-only = set only, no get [OK]

Hint: Write-only means no get accessor allowed [OK]

Common Mistakes:

• Leaving both get and set for write-only
• Changing field visibility instead of property
• Expecting set to return a value

5.

You want to create a class Secret that stores a string value. The value should be settable but never readable from outside the class. Inside the class, you want to log the value whenever it is set. Which property implementation achieves this?

hard

A. public string Data { set { Console.WriteLine(value); _data = value; } }

B. public string Data { get { return _data; } private set { _data = value; } }

C. public string Data { get; set; }

D. public string Data { private get; set { Console.WriteLine(value); _data = value; } }

Solution

1. Step 1: Identify write-only property with logging

   The property must have only a set accessor to be write-only and log the value when set.

2. Step 2: Check each option

   public string Data { set { Console.WriteLine(value); _data = value; } } has only a set accessor that logs and assigns the value, matching requirements.

3. Final Answer:

   public string Data { set { Console.WriteLine(value); _data = value; } } -> Option A

4. Quick Check:

   Write-only with logging in set accessor [OK]

Hint: Write-only property has only set accessor with logging code [OK]

Common Mistakes:

• Adding get accessor making property readable
• Using private get instead of no get
• Not logging inside set accessor