Read-only and write-only properties in C Sharp (C#) - Step-by-Step Execution

Concept Flow - Read-only and write-only properties

Define Property

↓

Is it Read-only?

Yes→Only get accessor

↓

Can read value

↓

Is it Write-only?

Yes→Only set accessor

↓

Can set value

↓

Has both get and set

↓

Can read and write value

This flow shows how a property can be defined as read-only (only get), write-only (only set), or both (get and set).

Execution Sample

C Sharp (C#)

class Person {
  private string name;
  public string Name { get => name; } // Read-only
  private string secret;
  public string Secret { set => secret = value; } // Write-only
}

Defines a class with a read-only property 'Name' and a write-only property 'Secret'.

Execution Table

Step	Action	Property Accessed	Operation	Result/Effect
1	Create Person instance	-	-	Person object created with default fields
2	Set Name property	Name	set	Error: No set accessor, cannot assign
3	Get Name property	Name	get	Returns current 'name' value (default null)
4	Set Secret property	Secret	set	Sets 'secret' field to assigned value
5	Get Secret property	Secret	get	Error: No get accessor, cannot read
6	Add set accessor to Name	Name	set	Now can assign value to 'name'
7	Set Name property	Name	set	'name' field updated
8	Get Name property	Name	get	Returns updated 'name' value

💡 Execution stops after demonstrating read-only and write-only property access and errors.

Variable Tracker

Variable	Start	After Step 4	After Step 7	Final
name	null	null	"Alice"	"Alice"
secret	null	"mySecret"	"mySecret"	"mySecret"

Key Moments - 3 Insights

Why does setting the read-only property 'Name' cause an error?

Because 'Name' only has a get accessor (see step 2 in execution_table), so it cannot be assigned a value.

Why can't we read the write-only property 'Secret'?

Because 'Secret' only has a set accessor (see step 5), so reading it is not allowed and causes an error.

What changes when we add a set accessor to 'Name'?

Now 'Name' can be assigned a value (step 6 and 7), allowing both reading and writing.

Visual Quiz - 3 Questions

Look at the execution_table, what happens when we try to set the 'Name' property at step 2?

A The 'name' field is updated

B An error occurs because there is no set accessor

C The 'secret' field is updated

D The property returns null

💡 Hint

Check step 2 in the execution_table where setting 'Name' causes an error.

According to variable_tracker, what is the value of 'secret' after step 4?

A null

B "Alice"

C "mySecret"

D Error

💡 Hint

Look at the 'secret' row after step 4 in variable_tracker.

If we remove the get accessor from 'Name', what would happen when trying to read it at step 8?

A It causes an error because get accessor is missing

B It returns the current value

C It sets the value instead

D It returns null always

💡 Hint

Refer to step 5 in execution_table where missing accessor causes error.

Concept Snapshot

Read-only property: has only get accessor, can only read value.
Write-only property: has only set accessor, can only assign value.
Both get and set: property can be read and written.
Trying to access missing accessor causes compile-time error.
Use private fields to store property data.

Full Transcript

This example shows how properties in C# can be read-only or write-only. A read-only property has only a get accessor, so you can read its value but cannot assign to it. A write-only property has only a set accessor, so you can assign a value but cannot read it. Trying to use a missing accessor causes an error. Adding both get and set allows reading and writing. The variable tracker shows how the underlying fields change as properties are accessed or assigned.