Indexers and Properties in C#

What are Properties in C#?

Properties in C# are special members of a class that provide a flexible mechanism to read, write, or compute the values of private fields. They encapsulate data and help in data validation.

Key Features of Properties

• Encapsulates fields with controlled access.
• Provides get and set accessors.
• Supports auto-implemented properties for cleaner code.
• Allows property validation inside set accessor.

Example: Defining and Using Properties

The following example demonstrates how to declare and use properties in C#.

Example: Properties in C#

public class Person
{
    private string name;
    private int age;

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

    public int Age
    {
        get { return age; }
        set
        {
            if (value > 0)
                age = value;
            else
                Console.WriteLine("Age must be positive.");
        }
    }
}

// Usage
class Program
{
    static void Main()
    {
        Person person = new Person();
        person.Name = "Alice";
        person.Age = 25;

        Console.WriteLine($"Name: {person.Name}, Age: {person.Age}");
    }
}

// Output:
// Name: Alice, Age: 25
        

The Name and Age properties control access to private fields, enforcing data validation.

Auto-Implemented Properties

C# provides auto-implemented properties for simpler code when no additional logic is needed.

Example: Auto-Implemented Properties

public class Employee
{
    public string Name { get; set; }
    public int Salary { get; set; }
}

// Usage
Employee emp = new Employee { Name = "John", Salary = 50000 };
Console.WriteLine($"Employee: {emp.Name}, Salary: {emp.Salary}");

// Output:
// Employee: John, Salary: 50000
        

The Name and Salary properties are automatically managed by C# without explicit fields.

What are Indexers in C#?

Indexers allow instances of a class to be accessed like an array. They provide a way to create classes that behave like collections.

Key Features of Indexers

• Allows objects to be accessed like an array.
• Uses the this keyword.
• Supports multiple parameters for multi-dimensional indexing.
• Useful for implementing collections.

Example: Defining and Using Indexers

The following example demonstrates how to define and use an indexer in C#.

Example: Indexers in C#

using System;

public class StudentCollection
{
    private string[] students = new string[3];

    public string this[int index]
    {
        get { return students[index]; }
        set { students[index] = value; }
    }
}

// Usage
class Program
{
    static void Main()
    {
        StudentCollection studentList = new StudentCollection();
        studentList[0] = "Alice";
        studentList[1] = "Bob";
        studentList[2] = "Charlie";

        Console.WriteLine(studentList[1]); // Output: Bob
    }
}
        

Here, StudentCollection allows access to student names using array-like indexing.

When to Use Properties and Indexers?

• Use properties for encapsulating fields with controlled access.
• Use auto-implemented properties when no additional logic is needed.
• Use indexers when creating classes that behave like collections.