C# - Properties

Properties in C# 

Introduction to C# Properties

In C# programming, properties play a vital role in implementing encapsulation in C# and controlling access to class data. A property in C# is a member of a class that provides a flexible mechanism to read, write, or compute the value of a private field. Instead of exposing fields directly, developers use properties to protect data integrity and apply validation logic.

If you are learning C# OOP concepts, understanding C# Properties is essential because they are tightly connected with object-oriented programming in C#, data hiding, abstraction, and secure code design.

In this detailed tutorial, we will explore:

• What are Properties in C#?
• Why use properties instead of public fields?
• Getter and Setter methods
• Auto-implemented properties
• Read-only and write-only properties
• Static properties
• Expression-bodied properties
• Access modifiers in properties
• Validation using properties
• Best practices for C# properties

What are Properties in C#?

A Property in C# is a special member of a class that provides a way to access private fields safely. It uses get and set accessors to retrieve and assign values.

In simple terms:

• get accessor → Returns the value
• set accessor → Assigns a value

Basic Syntax of a Property in C#

class Student
{
    private string name;

    public string Name
    {
        get
        {
            return name;
        }
        set
        {
            name = value;
        }
    }
}

Here:

• name is a private field
• Name is a public property
• value is a keyword used inside set accessor

Why Use Properties in C# Instead of Public Fields?

Using public fields directly breaks encapsulation in C#. Properties provide:

• Data validation
• Controlled access
• Flexibility to change internal logic
• Better maintainability
• Security

Problem with Public Fields

class Student
{
    public int Age;
}

Anyone can assign negative values:

Student s = new Student();
s.Age = -5;

This can lead to invalid data.

Using Property with Validation

class Student
{
    private int age;

    public int Age
    {
        get { return age; }
        set
        {
            if (value > 0)
                age = value;
        }
    }
}

Now invalid values cannot be assigned.

Getter and Setter in C#

Get Accessor

The get accessor returns the value of a field.

Set Accessor

The set accessor assigns a value using the implicit keyword value.

Example Program

using System;

class Employee
{
    private double salary;

    public double Salary
    {
        get { return salary; }
        set
        {
            if (value >= 0)
                salary = value;
        }
    }
}

class Program
{
    static void Main()
    {
        Employee emp = new Employee();
        emp.Salary = 50000;
        Console.WriteLine(emp.Salary);
    }
}

Auto-Implemented Properties in C#

C# provides a simplified way to declare properties without defining a private field manually. These are called Auto-Implemented Properties in C#.

Syntax

public string Name { get; set; }

Example

class Student
{
    public string Name { get; set; }
    public int RollNumber { get; set; }
}

The compiler automatically creates a hidden private backing field.

Read-Only Properties in C#

A property with only a get accessor is called a Read-Only Property in C#.

Example

class Person
{
    private DateTime birthDate;

    public Person(DateTime date)
    {
        birthDate = date;
    }

    public DateTime BirthDate
    {
        get { return birthDate; }
    }
}

Write-Only Properties in C#

A property with only a set accessor is called a Write-Only Property in C#.

class Secret
{
    private string password;

    public string Password
    {
        set { password = value; }
    }
}

Static Properties in C#

A Static Property in C# belongs to the class rather than an instance.

class Company
{
    public static string CompanyName { get; set; }
}

Access without creating object:

Company.CompanyName = "Tech Corp";

Expression-Bodied Properties in C#

Modern C# supports Expression-Bodied Properties for concise syntax.

class Circle
{
    public double Radius { get; set; }

    public double Area => 3.14 * Radius * Radius;
}

Access Modifiers in Properties

You can control accessibility of get and set separately.

public string Name { get; private set; }

Here, set is accessible only within the class.

Backing Field in C# Properties

A backing field is a private variable that stores the value of a property.

private int marks;

public int Marks
{
    get { return marks; }
    set { marks = value; }
}

Properties vs Methods in C#

Both properties and methods provide access to data. However:

• Properties are used for data access.
• Methods perform actions.

Use properties when:

• No heavy computation
• No side effects
• Acts like field access

Encapsulation in C# Using Properties

Encapsulation is a core OOP concept in C#. Properties ensure data hiding and controlled access.

Advantages:

• Prevents invalid data
• Improves maintainability
• Enhances security
• Supports abstraction

Advanced Property Features

Init-Only Properties (C# 9)

public string Name { get; init; }

Can be set only during object initialization.

Computed Properties

public int YearOfBirth => DateTime.Now.Year - Age;

Common Interview Questions on C# Properties

1. What is the difference between property and field?

Fields store data directly. Properties provide controlled access.

2. What is auto-implemented property?

A property without explicit backing field.

3. Can we make setter private?

Yes, to restrict modification.

Understanding C# Properties is fundamental for mastering C# programming language and object-oriented programming in C#. Properties enhance encapsulation in C#, improve code maintainability, and ensure data security.

From basic getter and setter methods to advanced features like expression-bodied and init-only properties, properties are an essential part of professional C# development.