Object-oriented programming languages have two different essential concepts, namely objects and classes. An object is an instantiation of a class. The difference is very conceptual, even though some people use them interchangeably.
Objects vs Classes
The main difference between objects and classes is that objects are an instance of a class, whereas a class acts as a blueprint that can be used to created instances like objects. Classes work as a sort of template for an object, and they can also describe object behavior.
An object can be defined as a physical entity that is used in using commands of a programming language. It is an instance of a class and can be a variable, data structure, function, or value. It mainly consists of two things, data (also known as a state) and code (also known as behavior). Each object is responsible for carrying out its own tasks in programming.
On the other hand, a class acts as a blueprint of an object. It is a form of concept that can be used in object-oriented programming languages. It represents every information and all the methods that an object should have. It also helps in providing values for member variables (state) and implementations of behavior in various programs.
Comparison Table Between Objects and Classes
| Parameters of Comparison | Objects | Classes |
| Concept | It is one of the instances of class. | It is a blueprint which can be used to create various instances. |
| Variables | Variable | Type |
| Memory | Allocated memory. | No allocated memory |
| Existence | Physical existence | Logical existence |
| Declaration | Can be declared multiple times | Can only be declared once. |
| Manipulated | Can be manipulated. | Cannot be manipulated. |
| Keywords | Developed in C++ with a class name and new keywords in Java. | Declared with class keywords. |
| Associated Value | Has associated values. | Has no values that can be associated. |
What are Objects?
An object is a physical entity that contains methods and properties that allow the use of data. It assists you in determining the class conduct. An object can be a variable, data structure, or function with a memory location allocated to it. The project is organized into hierarchical categories.
An object is a collection of characteristics and methods used to make a specific type of data value. In addition to polymorphism and inheritance, an object is an extension of an abstract data type. The key to programming is that each object is responsible for carrying out tasks on its own.
The properties of an object are what it knows, and the methods are what it can do. The methods give application functionality and ensure that an object’s data is used correctly. Methods also enable the concealment and standardization of task execution for specific operations on various sorts of objects. Methods are used to access a class’s objects.
Objects can be declared several times and with the help of class names developed in C++ and the new keywords available in Java. It does allocate memory after its creation which also means that it cannot be manipulated.
What are Classes?
A class is a logical entity that dictates the behavior of an object and what it will contain, hence acting as a blueprint. It gives all the initial values for member functions or methods and member variables. It’s a subroutine that makes an object; it’s an expandable guide for constructing objects. It encapsulates all of the data and methods that an object should have. Multiple objects can be created using a single class. It’s a TYPE declaration that’s been extended.
Its data type is essentially user-defined and comes with its own set of data members and member functions. This can be accessed and used by establishing a class instance.
Classes are an essential part of OOP. With the use of classes, variables and methods can be isolated in specific objects instead of being available to all elements of the program. Through this data encapsulation, each class can be protected from modification in other areas of the program. Developers can design organized applications using source code that can be easily modified by using classes.
Classes can only be declared once and by using a class keyword like class student {}. It also doesn’t allocate any memory after its creation. Since they aren’t in the memory, it means that they cannot be manipulated.
Main Differences Between Objects and Classes
- The difference between objects and classes is that an object is an instance of the class which can be used by programmers to use different methods from inside the class. On the other hand, classes are blueprints that can be used by programmers to create different instances.
- Object tends to act like a variable, whereas a class acts as a type and can be used to gather data and methods together into a single unit.
- An object will allocate memory when it is created, and a class won’t allocate any memory.
- Objects are physical entities. On the other hand, classes are logical entities.
- In terms of declarations, objects can be declared multiple times as per the requirement, where classes can only be declared once.
- Objects are created in C++ with new keywords available in Java and a class name, whereas classes can be declared with class keywords.
- An object has values that are associated with it. A class does not have any values that can be associated.
Conclusion
Objects and classes are an integral part of object-oriented programming languages. They differ conceptually. The main difference is that a class can be thought of as a structure that encapsulates a bunch of variables and methods, and an object serves as a member or instance of the class, which is an important aspect of object-oriented programming. An object is a physical entity, whereas a class is a logical entity. The keywords required to create both also differ in different programming languages. An object has an associated value that isn’t present in a class.
References
- https://dl.acm.org/doi/abs/10.1145/1932682.1869489
- https://link.springer.com/chapter/10.1007/BFb0053572