10 Differences Between class and structure

Class vs Structure: Understanding the Differences

Class and structure are two fundamental concepts in object-oriented programming. While they share some similarities, they also have distinct characteristics that set them apart. In this article, we will explore the differences between class and structure, along with their respective uses and examples.

What is a Class?

A class is a blueprint for creating objects (instances) that encapsulate data and behavior. It defines the properties (attributes) and actions (methods) that objects of a certain type can exhibit. In other words, a class serves as a template or a template for creating objects.

Examples of Classes

To understand the concept better, let’s consider a few examples of classes:

  • PersonClass: Represents a person with attributes like name, age, and methods like greet().
  • Car: Represents a car with attributes like brand, model, and methods like startEngine() and stopEngine().
  • Rectangle: Represents a geometric rectangle with attributes like length, width, and methods like calculateArea() and calculatePerimeter().

Uses of Classes

Classes are used for various purposes in software development. Some common uses include:

  • Modular Code: Classes promote modular code organization by encapsulating related properties and methods.
  • Inheritance: Classes facilitate inheritance, allowing new classes to inherit attributes and behaviors from existing classes.
  • Code Reusability: Classes can be reused to create multiple instances of objects with similar properties and behaviors.

What is a Structure?

A structure, also known as a struct, is a user-defined composite data type. It groups related data items of different types together, treating them as a single unit. Unlike classes, structures do not support methods or inheritance.

Examples of Structures

Here are a few examples of structures in different contexts:

  • Employee: Contains attributes like name, age, and salary representing an employee’s information.
  • Point: Represents a point in a 2D or 3D coordinate system with attributes x, y, and z.
  • Date: Contains attributes like day, month, and year to represent a specific date.

Uses of Structures

Structures serve various purposes in programming. Some common uses include:

  • Data Representation: Structures are used to represent complex data structures and composite entities.
  • Data Serialization: Structures facilitate the serialization and deserialization of data for storage or communication.
  • Performance Optimization: Structures are often used to optimize memory layout and improve performance in certain scenarios.

Differences between Class and Structure

Let’s now explore the key differences between classes and structures in a comprehensive table:

Difference Area Class Structure
Declaration Syntax Declared using the “class” keyword. Declared using the “struct” keyword.
Inheritance Supports single and multiple inheritance. Does not support inheritance.
Methods Can have methods (functions). Cannot have methods.
Access Modifiers Supports access modifiers like public, private, and protected. Does not support access modifiers.
Memory Allocation Objects are allocated on the heap. Objects are allocated on the stack (value type).
Default Constructor Classes have a default constructor, i.e., a constructor with no parameters. Structures do not have a default constructor.
Nullability Class instances can be null (reference type). Structures cannot be null (value type).
Assignment Classes are assigned by reference. Structures are assigned by value (copy).
Memory Overhead Classes tend to have higher memory overhead. Structures have lower memory overhead.
Use Cases Classes are suitable for complex entities and behaviors. Structures are suitable for small, lightweight data structures.


In summary, classes and structures serve different purposes in object-oriented programming. Classes are used to create objects with properties and behaviors, supporting inheritance and methods, while structures group related data items together without methods or inheritance. Understanding the differences between classes and structures is essential for writing efficient and maintainable code.

People Also Ask

Here are some common questions related to classes and structures:

  • Q: Can a class inherit from a structure?
  • No, structures cannot be used as base classes for class inheritance.

  • Q: Can a structure have methods?
  • No, structures cannot have methods. They only hold data.

  • Q: When should I use a class instead of a structure?
  • You should use a class when you need complex entities with behaviors and inheritance support.

  • Q: Can a class contain a structure as one of its members?
  • Yes, a class can contain a structure as one of its members.

  • Q: Is there a performance difference between classes and structures?
  • Structures have lower memory overhead and can offer performance benefits in certain scenarios.

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