Classes & Objects in C++: Concepts & Examples

Introduction

Classes and objects are the foundation of object-oriented programming (OOP) in C++. They allow programmers to model real-world entities by combining data and functions into a single unit. A class acts as a blueprint that defines properties and behaviors, while an object is an actual instance of that class. Understanding classes and objects helps beginners write more organized, reusable, and scalable programs. In this blog post, we’ll explore how classes and objects work in C++, why they are important, and how they help in building real-world applications.

Let’s Explore Classes & Objects in C++

Today, we going to create both Classes and Objects in C++. We are going to create a class with multiple objects inside it. 

First we are going to create a class like this inside the text editor but also outside the main function:

class Car {
    public:
    	// line of code
        // line of code
        // line of code
};

We can access different classes from inside the code to simplify complex codes, and make more understandable structure.

Second we are going to create objects inside the class. We will define the objects like we have a class named car then we create a weight object. We will create the objects like this:

class Car {
    public:
    	int weight;
        int old;
};

At last to see how we are going to access different objects inside the different classes and outside the main function, we will decide and print the values inside those objects from the main function. To do this we going to use dot(.) like this:

c.weight;

Now, Here's the overall code to understand all these statements better:

As you can see in the above code, we creating a class named "Book" then we are creating multiple variables inside it like title, author, and pages. At last, we are accessing the class from the main function and created two objects with different values inside them, then we tried to print one of object's variable. And it seems the program is printing the desired value, it means our code is working perfectly.

Important Notes

When learning classes and objects in C++, beginners often overlook some key details that can cause confusion later. One common mistake is forgetting that class members are private by default. If you don’t explicitly use public:, you won’t be able to access variables or functions from outside the class, which can lead to access errors.

Another important point is that a class is only a blueprint, not the actual data. You must create an object of the class before using its variables or functions. Each object has its own separate copy of data, so changing one object’s values does not affect another object.

Beginners also sometimes confuse variables inside a class with normal variables. These variables belong to the object, not directly to the class itself. To access them, the object must be created and the dot (.) operator must be used correctly.

It’s also important to remember that classes are usually defined outside the main() function, while objects are typically created inside main() or other functions. Defining a class inside main() is not allowed in standard practice.

Lastly, while learning, many beginners only store data inside classes. However, classes are meant to hold both data and functions (methods). As you progress, start adding functions inside your classes to make your programs more organized and realistic.

Understanding these small but crucial points will make object-oriented programming in C++ much clearer and will prepare you for advanced concepts like constructors, inheritance, and encapsulation.

Conclusion

Classes and objects make C++ programs more structured and easier to manage by following object-oriented principles. Once you understand how to create classes, define data members and member functions, and instantiate objects, you can design programs that closely reflect real-life scenarios. Mastering this concept also prepares you for advanced OOP topics such as inheritance, polymorphism, and encapsulation. Keep practicing by building small class-based programs, and you’ll gradually gain confidence in writing professional and maintainable C++ code.