Class vs Struct in C# NET or What are the differences between Class and Structure

To kick off your journey into software development with C#.NET you must be at least aware of the most elementary pieces: classes and structures. In this comparative overview, you will be presented with the primary differences and how both concepts can be used in the real world, so you will be able to make the right choices in software construction.

Classes and Structures Overview

In fact, classes and structures are features in C# coding that are much similar to one another in the way they encase dataᅳalmost like twin features when it comes to object creation and promoting object-oriented programming values. They have similarities between them, and this is what brings out the differences, which stem from the nature of their design and how the system interacts with them.

What is a class?

Classes are reference types. If you have an instance of a class, it resides in the heap at that moment, and what you are working with is the pointer to that memory address, not the data.

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

	public double CalculateArea()
	{
		return Math.PI * Radius * Radius;
	}
}

Here, the Circle class represents a kind of geometric figure, having one property, radius, and a single method, CalculateArea.

Features:

1. Nature Reference: Class variables reside in the heap memory and address references to the pointers of the heap memory.
2. Inheritance: Through this process of inheritance, classes can be defined to pass the common attributes and functions of other classes.
3. Memory Management: The memory for the class instances is garbage-collected by the.NET runtime, whereby they are placed upon the heap.
4. Flexibility: Classes can have special constructor without parameters, destructors, and implement interfaces.

What is a structure?

Structs are value types. They mainly provide a way to capture small data enclosures or are used in cases where one has to encapsulate an entity that has just one field, for example, a number. Its instances are always computed on a stack allocation or inlined for larger types.

public struct Point
{
    public double X { get; set; }
    public double Y { get; set; }
}

An example of the definition of a struct Point is a two-dimensional point in space with X and Y coordinates.

Features:

1. Value-Based: The structures are residing in stack memory, or they are in-lined within larger types, while the variables contain the data itself.
2. No Inheritance: Interfaces can be implemented in structures, but no structure or class can be inherited from another structure or class.
3. Automatic Memory: Since these vars are on the stack, their memory is automatically freed when the struct leaves the scope.
4. High Performance: They are optimized for small things. Therefore, they access and act quicker.

Memory Allocation

It is necessary to know the various ways in which C# classes and structures allocate memory in order to understand memory allocation thoroughly. This directly improves efficiency and optimizes the use of memory.

Class: Heap Allocation

C# classes live in heap-based memory. The heap is memory allocated to objects residing for longer times, or it is too large to sit on the stack. However, heap memory management needs a garbage collector that can free objects no more needed. This can add extra overhead to the process and may impact efficiency.

SampleClass exampleClass = new SampleClass();

The exampleClass object is an instance of SampleClass and it is kept on heap memory.

The heap memory is more flexible and can fit to larger memory requirements, hence it is suitable for larger objects or another type whose lifespan can be different. However, in general, access time to heap memory is slower than the time which is used to access stack memory and due to the garbage collecting process, there is also extra operation which can have an influence on the general efficiency of the application.

Struct: Stack Allocation

In C#, structures are value types and are usually stored on the stack. The stack is that part of memory in LIFO order. It mainly contains temporary objects and information related to stack frames and gives quick access but limited memory.

SampleStruct exampleStruct;
exampleStruct.Value = 10;

In this code, there is a variable exampleStruct of type SampleStruct. This variable is on stack.

Stack allocation is one of the basic properties of a struct; it means that access is faster and memory is autoreleased. When a struct becomes superfluous, its memory is released instantly; that process gives more performance, particularly for smaller and short-lived objects. The stack is a memory-space-constrained resource in that, with large objects added to it, there can be a stack overflow.

Syntax and Declaration

What is fundamental in the effective coding of C# are classes and structures. Both classes and structures face different approaches in their declaration and initialization. Therefore, a need to understand the differences is established for the optimum code and free of errors.

Class Syntax

A class in C# is declared by using the class keyword. Members defining the fields, methods, properties, and others, which define the characteristics of objects of the class, can be included in a class. There are different access modifiers for class members, for example, public, private, protected, and so on, that determine the visibility and accessibility of them.

public class Client
{
    private string completeName;

    public Client(string completeName)
    {
        this.completeName = completeName;
    }
}

In this example, definition of a class Client, which has a field completeName, which in turn is defined by yourself and a public constructor that sets its value.

It’s very convenient with the syntax and declaration for classes in C# to enable developers to come up with complex objects upon which behaviors associated with them and their states are through fields/properties. This has made it possible for encapsulation, inheritance, and polymorphism to be used in laying the proper foundation for a sound, strong, and flexible object-oriented environment.

Struct Syntax

A struct in C# is declared using the keyword struct and is also known as a struct. It can contain fields, methods, custom properties just like a class. Only, a struct does not include a base class, and it cannot be the base of a derived class. Structures do not support explicit parameter-less constructors.

public struct Coordinate
{
    public int Latitude, Longitude;

    public Coordinate(double latitude, double longitude)
    {
		Latitude = latitude;
        Longitude = longitude;
    }
}

Here a Coordinate struct is declared with two public fields: Latitude and Longitude, and a constructor to set their values.

A struct is declared similarly to the way a class is declared, differing only with the use of the struct keyword in place of class. Use structs to define simple read-only data structuresᅳstructures that are lightweight and don’t require the features of a class. Structs are best suited for small data structures that are created and destroyed frequently.

Access Modifiers

C# access modifiers are one of the elemental factors related to defining the scope and visibility of classes, structs, and their members. These access modifiers describe how entities and their members can be accessed from outside code and, therefore, help with the concept of encapsulation in object-oriented programming.

Class Access Modifiers

The access level of class members is controlled within classes using access modifiers like public, private, and protected. A public member can be accessed from anywhere within the program, while a private member can only be accessed within its container class. A protected member can be accessed both from the inheriting class and the native class.

public class AccessExample
{
    private int privateValue;
    public int PublicValue { get; private set; }
}

This code contains a class, AccessExample, whose private field is privateValue and public property is PublicValue. Code outside this class can access the public property, but the only code that accesses the private field is that which belongs to the AccessExample class, and the field is, in a sense, read-only for everything else.

This enables you to have a grip on visibility and scope by utilizing access modifiers in classes to help wrap up the details of a class and avoid them in the outer code. This way, your code will be more resistant and maintainable by the act of self-protection against outside manipulation of details from the implementation, promoting interaction through interfaces.

Struct Access Modifiers

Just as in the case of classes, structs can use access modifiers to control the visibility and scope of their members.

public struct AccessStructExample
{
    private int privateValue;
    public int PublicValue { get; private set; }
}

Here ‘s a structure AccessStructExample with a private field privateValue and a public property PublicValue similar to the class example above.

Using access modifiers in a struct is done in much the same way as in a class, and it affords the same means of encapsulation and safe interaction with instances of the struct. However, since the struct is a value type, encapsulation would benefit performance and application in a different way. It is very important that a struct be immutable and this should be maintained for the application served by it.

Inheritance

Inheritance is at the heart of object-oriented programming. C# fully supports inheritance. That means a class can derive from another class, from the base class. Thus, it is important to understand how inheritance behaves for classes and structs in order to design and code in an object-oriented way effectively in C#.

Class: Inheritance

In C#, it can inherit fields, properties, and methods from a base class. This, therefore, gets to support the concept of reusing code, and there gets to be a very strong relationship that is born between the parent and child classes. The base keyword helps to achieve this from the base class if the components making up the derived class are those that are intended to be interacted with by their parent class.

public class Creature
{
    public void Consume() 
    {
        Console.WriteLine("Eating...");
    }
}

public class Dog : Creature
{
    public void Howl() 
    {
        Console.WriteLine("Barking...");
    }
}

The following is an example of how the Dog class acquires the Consume method from the base class Creature class, which in basic terms defines class inheritance in C#.

C# inheritance belongs to class inheritance, where it is well advocated that code reusability, polymorphism, and a structured hierarchy of classes can extend and override composed member possibilities in the derrived class; hence, flexibility is achieved and a lean and systematic approach develops in an object-oriented project.

Struct: No Inheritance

Unlike the classes in C#, the structs do not have any inheritance features. They cannot inherit from the other structs or classes, and also they cannot become a class’s base. Still, all the structs are implicitly inherited from the System.ValueType, and which is in turn inherited from the System.Object.

public struct ImmutableInteger
{
    public int IntValue;
}

This code declares a simple structure. Such a structure cannot be a base type, and cannot inherit from any other class or structure except System.ValueType.

The absence of inheritance in structs further signifies them as mean and lean data structures by themselves. This keeps the ordering of structs simple and effective, and one such that complications and added bulk because of inheritance do not arise.

Usage Scenarios

However, it is always important for one to understand the difference between a class and a struct, especially when it comes to choosing the right type in the situations that we run into during C# development. He should be aware of their individual traits and the implications arising from them to make informed choices on functionality and performance.

When to Use a Class

Classes are preferred in case object identity and lifetime of an object are concerned, where instances may show a change in their own structure after creation, when inheritance and polymorphism is needed.

public class Client
{
    public string CompleteName { get; set; }
    public string Email { get; set; }
}

For instance, the appropriate class here is the Client class, since clients typically have numerous attributes and behaviors, and therefore they would be treated differently in the application.

Choosing classes when properties such as inheritance, polymorphism, and mutable instances are used makes the code ordered, maintainable, and adaptable. However, this might be more memory-consuming and may slow down access and operations.

When to Use a Struct

Structs excel when used for small, state-heavy objects that are created and destroyed over and over, and where the instances don’t change post-instantiation. They’re great for representing simple data structures and value types where the identity of an object is not a concern.

public struct Coordinate
{
    public double Latitude { get; }
    public double Longitude { get; }

    public Coordinate(double latitude, double longitude)
    {
        Latitude = latitude;
        Longitude = longitude;
    }
}

The struct Coordinate is a good choice, as it is a very simple data structure with a clear and fixed state, for which one does not need the extra features that classes provide.

In a way, the power of using structs for specific situations is that the code comes out efficient, fast, and straightforward. This unfolds flexibility in memory and lets the operation happen on the fly. However, there are some things that structs are limited from doing, such as modeling inheritance and encapsulation of complex behaviors.

Limitations and Pitfalls

Both classes and structs in C# are very important, but both have a few limitations and pitfalls. Knowledge about these pitfalls helps developers to make conscious decisions to enhance the stability and performance of C# implementations.

Class Limitations

The class is powerful and flexible, but due to its reference-type nature, it may lead to the consumption of more memory. Besides, object memory management, especially in large applications, may become a tricky task. This kind of work may lead to memory leakage and performance issues.

public class ByteArrayContainer
{
    private byte[] data = new byte[1000000];
}

In the previous example, this class should be misused to lead to memory and performance issues, which determines the unsuitability of using this class.

Using classes in C# requires careful attention to both memory and object life. In large and complex applications, this is necessary to avoid memory leaks and ensure effective use of the memory. Even with all the advantages obtained by the use of inheritance and polymorphism with classes, there is still a need for careful management and optimization activities.

Struct Limitations

Although structs are more suitable for smaller and simpler data types, unfortunately, they have a few limitations. They cannot use all the features of object-oriented programming exposed by C#. Besides, as they are passed by value, using heavy structs may lead to performance issues.

public struct MassiveArray
{
    public byte[] Elements = new byte[1000000];
}

In this example, MassiveArray is not a good choice to be used as a struct because it is very large. This shows the potential performance issues when structs are used incorrectly.

When small, unchangeable objects are manipulated, choosing a struct makes better use of strengths. Nevertheless, for more extensive data constructs, or any other scenario that demands more advanced object-oriented capabilities, the limitations of structs can surely be seen, and keeping structs as the tool imposed could surely make your code suboptimal and more painful to maintain.

Practical Examples

Getting deep down with the differences between classes and structs, let’s see some practical examples in C# to show within which context the use of each is appropriate. It will reinforce the properties and benefits and make things clearer about when to choose one from the other.

Class in Action

Let’s say we are building a Customer Relationship Management (CRM) system in which you have to define a customer. Each customer will have different properties and possible behaviors (methods) and must be related to other systems.

public class Client
{
    public string ClientCode { get; private set; }
    public string CompleteName { get; set; }
    public string Email { get; set; }

    public Client(string clientCode)
    {
        ClientCode = clientCode;
    }

    public void SendEmail(string content)
    {
        // Logic to send an email to the client
    }
}

Examine the following example. The properties of the Client class are ClientCode, CompleteName, and Email. It has one behavior: SendEmail. It might be the case that the information representing a client changes, or the meaning of the identity and behavior of the object is more statement-like. In that case, we use a class.

Such a structure makes it easy to add further features in the future. Once the CRM system further develops, more functionalities, behaviors, and interactions can be added for the customer. Since you already have all the rich capabilities of a classᅳfrom relation to another object to inheriting its properties and having different behaviorsᅳjust go ahead and do it.

Struct in Action

Suppose you’re building a graphics app that simply renders 2D points in a canvas. Each point has a Latitude and Longitude coordinate.

public struct Coordinate
{
    public double Latitude { get; }
    public double Longitude { get; }

    public Coordinate(double latitude, double longitude)
    {
        Latitude = latitude;
        Longitude = longitude;
    }

    public double DistanceTo(Coordinate other)
    {
        const double R = 6371e3; // Earth's radius in meters
        double lat1 = Latitude * Math.PI / 180;
        double lat2 = other.Latitude * Math.PI / 180;
        double deltaLat = (other.Latitude - Latitude) * Math.PI / 180;
        double deltaLon = (other.Longitude - Longitude) * Math.PI / 180;

        double a = Math.Sin(deltaLat / 2) * Math.Sin(deltaLat / 2) +
                   Math.Cos(lat1) * Math.Cos(lat2) *
                   Math.Sin(deltaLon / 2) * Math.Sin(deltaLon / 2);
        double c = 2 * Math.Atan2(Math.Sqrt(a), Math.Sqrt(1 - a));

        double distance = R * c; // in meters
        return distance;
    }
}

In this example the Coordinate struct makes for a very natural 2D point. It is small, immutable after construction, and lacks all the additional baggage and functionality that comes along with classes.

Here again, by using a struct we will help ensure memory requirements are minimal, particularly for the scenario of regularly creating and destroying many Coordinate objects. The DistanceTo method is constructed in the way one would often expect for this sort of basic data type, and that by itself helps show that structs are very at home in the role.

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