DRY (Don't Repeat Yourself) in Software Engineering - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding the core idea of DRY

What is the main purpose of the DRY principle in software development?

A To repeat code in different places to make debugging easier.

B To write as many lines of code as possible for clarity.

C To avoid writing the same code or logic multiple times by reusing it.

D To create multiple copies of code for backup purposes.

💡 Hint

Think about how repeating code affects maintenance and errors.

The DRY principle encourages developers to avoid duplicating code. This helps reduce errors and makes maintenance easier by having a single source of truth.

🚀 Application

intermediate

Applying DRY to reduce code duplication

You have two functions that calculate the area of a rectangle and a square separately, but both use the same multiplication logic. How can you apply DRY to improve this?

A Keep both functions separate to avoid confusion.

B Create a single function that takes length and width as parameters and use it for both shapes.

C Copy the multiplication logic into a third function and call it inside both functions.

D Write the multiplication logic directly inside the main program instead of functions.

💡 Hint

Think about how one function can handle both shapes by using parameters.

By creating one function that accepts length and width, you avoid repeating the multiplication logic. This follows DRY by reusing code.

🔍 Analysis

advanced

Identifying DRY violations in code

Which of the following code snippets violates the DRY principle the most?

Software Engineering

def greet_morning():
    print('Good morning!')

def greet_evening():
    print('Good evening!')

def greet_night():
    print('Good night!')

A Each function repeats the print statement with only the greeting text changed.

B All functions use a single print statement with different parameters.

C Functions are combined into one with a parameter for the greeting.

D There is no repetition; each function is unique.

💡 Hint

Look for repeated code blocks that differ only slightly.

The code repeats the print statement in each function with only the greeting text changed. This is a clear DRY violation because the logic is duplicated.

❓ Comparison

advanced

Comparing DRY with WET (Write Everything Twice)

Which statement best explains the difference between DRY and WET principles?

A DRY encourages code reuse to avoid duplication, while WET accepts duplication and repeats code.

B DRY means writing code twice for safety, WET means writing code once.

C DRY and WET are the same principles with different names.

D WET is a modern replacement for DRY focusing on code repetition.

💡 Hint

Think about what each acronym stands for and their goals.

DRY stands for 'Don't Repeat Yourself' and promotes avoiding code duplication. WET stands for 'Write Everything Twice' and accepts duplication, often leading to harder maintenance.

❓ Reasoning

expert

Reasoning about DRY in large projects

In a large software project, which of the following is a potential downside of strictly applying DRY everywhere without careful design?

A Increased number of bugs due to code duplication.

B Having too many repeated code blocks making the project larger.

C Slower program execution because of repeated code.

D Overly complex shared code that is hard to understand and maintain.

💡 Hint

Consider what happens if you try to reuse code too much without clear structure.

While DRY reduces duplication, applying it without good design can create complicated shared code that is difficult to maintain and understand, which can hurt the project.