Read-only and write-only properties in C Sharp (C#) - Time & Space Complexity

Time Complexity: Read-only and write-only properties

O(1)

Understanding Time Complexity

We want to understand how the time it takes to use read-only and write-only properties changes as we work with more data.

How does the number of property accesses affect the program's speed?

Scenario Under Consideration

Analyze the time complexity of the following code snippet.

public class DataHolder
{
    private int[] numbers;

    public DataHolder(int size)
    {
        numbers = new int[size];
    }

    public int this[int index]  // Read-only property
    {
        get { return numbers[index]; }
    }

    public int WriteOnlyValue  // Write-only property
    {
        set { numbers[0] = value; }
    }
}

This code defines a class with a read-only index property to get values and a write-only property to set a value.

Identify Repeating Operations

Identify the loops, recursion, array traversals that repeat.

• Primary operation: Accessing an element in the array through the property.
• How many times: Each property access happens once per call; no loops inside the property itself.

How Execution Grows With Input

Each property access takes about the same time regardless of the array size.

Input Size (n)	Approx. Operations
10	1 per access
100	1 per access
1000	1 per access

Pattern observation: The time to get or set a single element does not grow with the size of the array.

Final Time Complexity

Time Complexity: O(1)

This means each property access takes a constant amount of time, no matter how big the data is.

Common Mistake

[X] Wrong: "Accessing a property that works with an array always takes longer if the array is bigger."

[OK] Correct: Accessing a single element by index is direct and does not depend on the array size, so it takes the same time regardless.

Interview Connect

Understanding how property access time works helps you explain how your code handles data efficiently, a useful skill in many programming tasks.

Self-Check

"What if the read-only property computed a sum of all elements each time it was accessed? How would the time complexity change?"

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