How to distinguish procedural programming from object-oriented programming in terms of their main technical characteristics?

Procedural programming is based on a sequence of procedure (function) calls that change the program's state. Main characteristics:

• The program consists of functions and data separately.
• Control flow of the program is through sequential execution of functions.
• There is no concept of objects and encapsulation.

Object-oriented programming (OOP) is built around objects that combine data and methods to operate on them. Main characteristics:

• Objects encapsulate state (fields) and behavior (methods).
• Principles of inheritance, polymorphism, and encapsulation are used.
• The program is modeled as an interaction of objects.

Example:

• In procedural style: there is a function calculateArea(width, height) that takes parameters and returns a result.
• In OOP: there is a class Rectangle with fields width and height and a method getArea() that returns the area.

// Procedural style
int calculateArea(int width, int height) {
    return width * height;
}

// Object-oriented style
class Rectangle {
    int width, height;
    int getArea() {
        return width * height;
    }
}