++
Object-oriented programming (OOP) is a popular approach to writing code that focuses on creating objects with properties and methods to perform specific tasks. While many languages have built-in support for OOP, C++ is a powerful and versatile language that allows developers to implement OOP concepts in their code.
In this article, we will explore the basics of writing object-oriented code in C++ and how it can improve the structure and organization of your programs.
Defining Classes in C++
The first step in writing object-oriented code in C++ is defining classes. A class is a user-defined data type that serves as a blueprint for creating objects. It contains attributes (data members) and methods (functions) that define the behavior of the objects.
To define a class in C++, we use the keyword "class" followed by the name of the class and a set of curly braces to enclose the class definition. For example:
```
class Rectangle {
// class definition
};
```
Defining Attributes and Methods
Once we have defined a class, we can add attributes and methods to it. Attributes are variables that hold data, while methods are functions that perform operations on the data.
In C++, attributes are declared within the class, and methods can be either declared within the class or defined outside of it. Let's add some attributes and methods to our Rectangle class:
```
class Rectangle {
private:
int width;
int height;
public:
void setWidth(int w) {
width = w;
}
void setHeight(int h) {
height = h;
}
int getArea() {
return width * height;
}
};
```
In the above example, we have declared two private attributes, width and height, and three public methods, setWidth(), setHeight(), and getArea(). Private attributes can only be accessed within the class, while public methods can be accessed from outside the class.
Creating Objects
To use a class, we need to create objects from it. We can create multiple objects from the same class, each with its own set of attributes and methods. To create an object in C++, we use the "new" keyword followed by the class name and a set of parenthesis. For example:
```
Rectangle* rect1 = new Rectangle();
```
This creates a new object of type Rectangle and assigns it to the pointer variable rect1. We can then use the dot operator to access the attributes and methods of this object, like so:
```
rect1->setWidth(5);
rect1->setHeight(10);
cout << rect1->getArea() << endl; // outputs 50
```
Inheritance
One of the key features of OOP is inheritance, which allows us to create new classes based on existing ones. In C++, we can achieve this using the "class" keyword followed by the name of the new class and a colon, followed by the name of the base class. For example:
```
class Square : public Rectangle {
// class definition
};
```
This creates a new class Square that inherits from the Rectangle class. This means that Square objects will have all the attributes and methods of Rectangle, plus any additional ones that we define in the Square class.
Polymorphism
Another important aspect of OOP is polymorphism, which allows us to use the same method to perform different operations on different objects. In C++, we can achieve this using virtual functions
