ChatGPT for Advanced C# Code Refactoring & Clean-Up

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Code refactoring for C# is essential for maintaining high-quality, readable, and efficient software. But let’s be honest—rewriting messy or outdated code can be a tedious process. Enter ChatGPT, your AI-powered coding assistant that can suggest modern, optimized solutions in seconds!

In this post, we’ll explore how ChatGPT can help you refactor complex C# code, using modern features like pattern matching, switch expressions, and LINQ. Whether you’re working with legacy code or looking to improve maintainability, these techniques will help you write cleaner and more efficient C#.

Why Advanced Code Refactoring Matters

Refactoring isn’t just about aesthetics—it impacts:

Readability – Easier to understand code means fewer bugs and faster development.
Maintainability – Cleaner code reduces technical debt and future headaches.
Performance – More efficient structures lead to better execution times.

Let’s walk through two real-world C# examples and see how ChatGPT can help us clean up our code.

Example 1: Simplifying C# Nested Conditionals With ChatGPT

Before Refactoring (Messy If-Else Code)

Here’s a method that calculates shipping costs based on various conditions. The code works, but it’s hard to read, deeply nested, and error-prone:

public class OrderProcessor
{
    public decimal CalculateShippingCost(Order order)
    {
        decimal cost = 0;
        if (order != null)
        {
            if (order.IsInternational)
            {
                if (order.Weight > 10)
                {
                    cost = order.Weight * 2.5m;
                }
                else
                {
                    cost = 20m;
                }
            }
            else
            {
                if (order.Weight > 5)
                {
                    cost = order.Weight * 1.5m;
                }
                else
                {
                    cost = 10m;
                }
            }
        }
        return cost;
    }
}

Using ChatGPT to Refactor C#

We asked ChatGPT:

“Refactor this method to remove nested conditionals using C# pattern matching and switch expressions.”

Refactored Version with ChatGPT (Using C# Pattern Matching & Switch Expressions)

public decimal CalculateShippingCost(Order order)
{
    if (order == null)
        throw new ArgumentNullException(nameof(order));

    return order switch
    {
        { IsInternational: true, Weight: > 10 } => order.Weight * 2.5m,
        { IsInternational: true, Weight: <= 10 } => 20m,
        { IsInternational: false, Weight: > 5 } => order.Weight * 1.5m,
        { IsInternational: false, Weight: <= 5 } => 10m,
        _ => throw new InvalidOperationException("Invalid order data")
    };
}

What Changed?

Eliminated Deep Nesting – No more multiple levels of if-else.
Improved Readability – Each condition is clearly defined.
Handled Edge Cases – Null checks and default cases are covered.

This version is easier to maintain, debug, and extend in the future.

Example 2: Removing Duplicate Logic with C# LINQ With ChatGPT

Before Refactoring (Repetitive If-Else Logic)

Here’s a method that calculates total discounts for different product categories. The logic is repetitive and hard to modify:

public decimal CalculateTotalDiscount(List<Product> products)
{
    decimal totalDiscount = 0;
    foreach (var product in products)
    {
        if (product.Category == "Electronics")
        {
            totalDiscount += product.Price * 0.1m;
        }
        else if (product.Category == "Clothing")
        {
            totalDiscount += product.Price * 0.2m;
        }
        else if (product.Category == "Books")
        {
            totalDiscount += product.Price * 0.05m;
        }
        else
        {
            totalDiscount += product.Price * 0.08m;
        }
    }
    return totalDiscount;
}

Using ChatGPT to Refactor

We asked ChatGPT:

“Refactor this method to remove repetitive if-else statements using LINQ and a dictionary for discount rates.”

Refactored Version (Using LINQ & Dictionary Lookup)

public decimal CalculateTotalDiscount(List<Product> products)
{
    var discountRates = new Dictionary<string, decimal>
    {
        { "Electronics", 0.1m },
        { "Clothing", 0.2m },
        { "Books", 0.05m }
    };

    return products.Sum(product =>
    {
        var rate = discountRates.TryGetValue(product.Category, out var r) ? r : 0.08m;
        return product.Price * rate;
    });
}

What Changed?

Replaced If-Else with a Dictionary – No more hardcoded category checks.
Used LINQ for Clarity – Sum() makes the logic concise and efficient.
Easier to Update – Adding a new category is as simple as updating the dictionary.

This version reduces duplicate logic and makes future modifications effortless.

Best Practices for Using ChatGPT in Code Refactoring

Want to make the most out of ChatGPT for code refactoring? Here are some tips:

1️⃣ Be Specific with Prompts – Clearly define your refactoring goals (e.g., “Replace loops with LINQ,” “Use switch expressions”).
2️⃣ Iterate for Better Suggestions – If the first response isn’t ideal, refine your prompt with more details.
3️⃣ Always Test the Code – AI-generated code may have edge cases or subtle issues—always validate its correctness.
4️⃣ Learn from the AI – Instead of just copying code, analyze the suggestions to improve your C# knowledge.

Final Thoughts

ChatGPT is a powerful assistant for refactoring C# code, but the best developers still review, refine, and test the results. By leveraging AI, you can reduce redundant logic, improve maintainability, and modernize your C# applications faster than ever.

💡 Have you used ChatGPT for refactoring? Share your experience in the comments below!

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