What, in your opinion, does writing quality code mean?

Cleanliness, readability, maintainability, testability, security, performance, compliance with standards and project requirements. Code should be easy to understand by other developers and for making future changes.

Main aspects of quality code:

• Readability: Using meaningful names for variables, functions, and classes. Proper formatting and indentation.
• Maintainability: Modularity, weak coupling of components. Minimal code duplication (DRY - Don't Repeat Yourself).
• Testability: Code that is easy to test automatically and manually. Presence of unit tests, integration tests.
• Security: Protection against vulnerabilities (XSS, SQL Injection, etc.). Input data validation.
• Performance: Efficient use of resources (memory, CPU). Avoiding bottlenecks.
• Standards compliance: Following accepted coding standards within the team or industry.
• Documentation: Comments on complex code, API documentation (if applicable).

Example of clean and readable code:

# Function to calculate the area of a rectangle
def calculate_rectangle_area(width, height):
    # Check that input data is positive
    if width <= 0 or height <= 0:
        raise ValueError("Width and height must be positive numbers")
    return width * height

# Using the function
rectangle_width = 10
rectangle_height = 5
area = calculate_rectangle_area(rectangle_width, rectangle_height)
print(f"Rectangle area: {area}")

Example of less clean code:

def calc_area(w, h): # Abbreviated and unclear names
    if w <= 0 or h <= 0: # No type check
        raise ValueError("Input must be positive") # Uninformative error message
    return w*h

The difference between the two examples demonstrates the importance of naming, readability, and error handling for code quality.