LINQ performance considerations in C Sharp (C#) - Mini Project: Build & Apply

LINQ Performance Considerations

📖 Scenario: You work with a list of products in a store. You want to find products that cost less than a certain price. Using LINQ makes this easy, but you also want to understand how to write it efficiently.

🎯 Goal: Build a simple C# program that uses LINQ to filter products by price, and learn how to write it in a way that is clear and performs well.

📋 What You'll Learn

Create a list of products with names and prices

Set a price limit variable

Use LINQ query syntax to select products cheaper than the limit

Print the filtered product names

💡 Why This Matters

🌍 Real World

Filtering lists of products or data quickly and clearly is common in apps like online stores or inventory systems.

💼 Career

Understanding LINQ and how to write efficient queries is important for C# developers working with data collections.

1

Create the product list

Create a List<Product> called products with these exact entries: new Product("Pen", 5), new Product("Notebook", 15), new Product("Eraser", 3), new Product("Backpack", 50).

C Sharp (C#)

public record Product(string Name, int Price);

using System.Collections.Generic;

class Program
{
    static void Main()
    {
        // Create the products list here
    }
}

Need a hint?

Use List<Product> and add the products inside curly braces.

2

Set the price limit

Create an int variable called priceLimit and set it to 10.

C Sharp (C#)

public record Product(string Name, int Price);

using System.Collections.Generic;

class Program
{
    static void Main()
    {
        List products = new List
        {
            new Product("Pen", 5),
            new Product("Notebook", 15),
            new Product("Eraser", 3),
            new Product("Backpack", 50)
        };
        // Set the priceLimit variable here
    }
}

Need a hint?

Use int priceLimit = 10; to create the variable.

3

Filter products with LINQ

Use a LINQ query with from, where, and select to create a variable called cheapProducts that selects products from products where Price < priceLimit.

C Sharp (C#)

public record Product(string Name, int Price);

using System.Collections.Generic;

class Program
{
    static void Main()
    {
        List products = new List
        {
            new Product("Pen", 5),
            new Product("Notebook", 15),
            new Product("Eraser", 3),
            new Product("Backpack", 50)
        };
        int priceLimit = 10;
        // Use LINQ query to select cheapProducts here
    }
}

Need a hint?

Use the LINQ query syntax with from, where, and select.

4

Print the filtered product names

Use a foreach loop to print the Name of each product in cheapProducts using System.Console.WriteLine(product.Name).

C Sharp (C#)

public record Product(string Name, int Price);

using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main()
    {
        List products = new List
        {
            new Product("Pen", 5),
            new Product("Notebook", 15),
            new Product("Eraser", 3),
            new Product("Backpack", 50)
        };
        int priceLimit = 10;
        var cheapProducts = from product in products
                            where product.Price < priceLimit
                            select product;
        // Print product names here
    }
}

Need a hint?

Use a foreach loop and Console.WriteLine(product.Name) inside it.