How did you add new features to your last implemented project?

In my last project, I added new features following the standard development cycle: first analyzing requirements, then designing architecture and interfaces, and then writing code using principles of modularity and reusability. For integrating new features, I used version control system (Git), creating separate branches for each task. After writing the code, I conducted local testing, followed by integration testing to ensure that the new features did not disrupt existing logic.

Example of adding a new function in Java:

public class Calculator {
    // Existing function
    public int add(int a, int b) {
        return a + b;
    }

    // New function - subtraction
    public int subtract(int a, int b) {
        return a - b;
    }
}

Thus, new functions are added as separate methods or classes, which facilitates maintenance and testing.