Why pattern matching matters in C Sharp (C#) - See It in Action

Why pattern matching matters

📖 Scenario: Imagine you work at a store that sells different types of products. Each product has a different way to calculate its discount. You want to write a program that checks the product type and calculates the discount correctly.

🎯 Goal: You will build a simple program that uses pattern matching to check product types and calculate discounts easily and clearly.

📋 What You'll Learn

Create a list of products with different types

Create a variable to hold the total discount

Use pattern matching with switch expressions to calculate discounts based on product type

Print the total discount

💡 Why This Matters

🌍 Real World

Pattern matching helps write clear and simple code when you have different types of data that need different handling, like products with different discount rules.

💼 Career

Many jobs require handling different data types and making decisions based on them. Pattern matching is a modern, readable way to do this in C#.

1

Create product classes and a list

Create three classes called Book, Food, and Clothing. Each class should have a public property Price of type decimal. Then create a list called products containing these exact items: a Book with price 20.0m, a Food with price 10.0m, and a Clothing with price 50.0m.

C Sharp (C#)

// Your code here

Need a hint?

Define each class with a Price property. Then create a list of type object and add one instance of each class with the given prices.

2

Create a variable to hold total discount

Inside the Main method, create a variable called totalDiscount of type decimal and set it to 0.

C Sharp (C#)

using System;
using System.Collections.Generic;

class Book
{
    public decimal Price { get; set; }
}

class Food
{
    public decimal Price { get; set; }
}

class Clothing
{
    public decimal Price { get; set; }
}

class Program
{
    static void Main()
    {
        List products = new List
        {
            new Book { Price = 20.0m },
            new Food { Price = 10.0m },
            new Clothing { Price = 50.0m }
        };
        // Create a decimal variable called totalDiscount and set it to 0
        // Your code here
    }
}

Need a hint?

Use decimal totalDiscount = 0m; to create the variable.

3

Calculate discounts using pattern matching

Use a foreach loop with variable product to go through products. Inside the loop, use a switch expression with pattern matching on product to calculate a discount: if product is Book, discount is 10% of Price; if Food, discount is 5% of Price; if Clothing, discount is 20% of Price; otherwise, discount is 0. Add each discount to totalDiscount.

C Sharp (C#)

using System;
using System.Collections.Generic;

class Book
{
    public decimal Price { get; set; }
}

class Food
{
    public decimal Price { get; set; }
}

class Clothing
{
    public decimal Price { get; set; }
}

class Program
{
    static void Main()
    {
        List products = new List
        {
            new Book { Price = 20.0m },
            new Food { Price = 10.0m },
            new Clothing { Price = 50.0m }
        };
        decimal totalDiscount = 0m;
        // Use foreach with product to loop over products
        // Use switch expression with pattern matching on product to calculate discount
        // Add discount to totalDiscount
        // Your code here
    }
}

Need a hint?

Use foreach (object product in products) and a switch expression with pattern matching to calculate discounts.

4

Print the total discount

Write a Console.WriteLine statement to print the text Total discount: followed by the value of totalDiscount.

C Sharp (C#)

using System;
using System.Collections.Generic;

class Book
{
    public decimal Price { get; set; }
}

class Food
{
    public decimal Price { get; set; }
}

class Clothing
{
    public decimal Price { get; set; }
}

class Program
{
    static void Main()
    {
        List products = new List
        {
            new Book { Price = 20.0m },
            new Food { Price = 10.0m },
            new Clothing { Price = 50.0m }
        };
        decimal totalDiscount = 0m;
        foreach (object product in products)
        {
            decimal discount = product switch
            {
                Book b => b.Price * 0.10m,
                Food f => f.Price * 0.05m,
                Clothing c => c.Price * 0.20m,
                _ => 0m
            };
            totalDiscount += discount;
        }
        // Print the totalDiscount with the text "Total discount: "
        // Your code here
    }
}

Need a hint?

Use Console.WriteLine($"Total discount: {totalDiscount}"); to print the result.