LINQ to Objects Samples - .NET Core Documentation

Filtering Data (Where)

Learn how to filter collections based on specific criteria using the Where extension method.


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

public class Product
{
    public int Id { get; set; }
    public string Name { get; set; }
    public decimal Price { get; set; }
    public int CategoryId { get; set; }
}

public class Sample1
{
    public static void Main(string[] args)
    {
        var products = new List
        {
            new Product { Id = 1, Name = "Laptop", Price = 1200.00m, CategoryId = 1 },
            new Product { Id = 2, Name = "Keyboard", Price = 75.00m, CategoryId = 1 },
            new Product { Id = 3, Name = "Mouse", Price = 25.00m, CategoryId = 1 },
            new Product { Id = 4, Name = "Monitor", Price = 300.00m, CategoryId = 2 },
            new Product { Id = 5, Name = "Webcam", Price = 50.00m, CategoryId = 2 }
        };

        // Select products with a price greater than 100
        var expensiveProducts = products.Where(p => p.Price > 100.00m);

        Console.WriteLine("Expensive Products:");
        foreach (var product in expensiveProducts)
        {
            Console.WriteLine($"- {product.Name} (${product.Price})");
        }
    }
}

Expected Output:
Expensive Products:
- Laptop ($1200.00)
- Monitor ($300.00)

Sorting Data (OrderBy, OrderByDescending)

Discover how to sort collections in ascending or descending order using OrderBy and OrderByDescending.


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

public class Product // Assuming Product class is defined as above
{
    public int Id { get; set; }
    public string Name { get; set; }
    public decimal Price { get; set; }
    public int CategoryId { get; set; }
}

public class Sample2
{
    public static void Main(string[] args)
    {
        var products = new List
        {
            new Product { Id = 1, Name = "Laptop", Price = 1200.00m, CategoryId = 1 },
            new Product { Id = 2, Name = "Keyboard", Price = 75.00m, CategoryId = 1 },
            new Product { Id = 3, Name = "Mouse", Price = 25.00m, CategoryId = 1 },
            new Product { Id = 4, Name = "Monitor", Price = 300.00m, CategoryId = 2 },
            new Product { Id = 5, Name = "Webcam", Price = 50.00m, CategoryId = 2 }
        };

        // Sort products by price in descending order
        var sortedProducts = products.OrderByDescending(p => p.Price);

        Console.WriteLine("Products Sorted by Price (Descending):");
        foreach (var product in sortedProducts)
        {
            Console.WriteLine($"- {product.Name} (${product.Price})");
        }
    }
}

Expected Output:
Products Sorted by Price (Descending):
- Laptop ($1200.00)
- Monitor ($300.00)
- Keyboard ($75.00)
- Webcam ($50.00)
- Mouse ($25.00)

Grouping Data (GroupBy)

Learn to group elements in a collection based on a specified key using GroupBy.


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

public class Product // Assuming Product class is defined as above
{
    public int Id { get; set; }
    public string Name { get; set; }
    public decimal Price { get; set; }
    public int CategoryId { get; set; }
}

public class Sample3
{
    public static void Main(string[] args)
    {
        var products = new List
        {
            new Product { Id = 1, Name = "Laptop", Price = 1200.00m, CategoryId = 1 },
            new Product { Id = 2, Name = "Keyboard", Price = 75.00m, CategoryId = 1 },
            new Product { Id = 3, Name = "Mouse", Price = 25.00m, CategoryId = 1 },
            new Product { Id = 4, Name = "Monitor", Price = 300.00m, CategoryId = 2 },
            new Product { Id = 5, Name = "Webcam", Price = 50.00m, CategoryId = 2 }
        };

        // Group products by CategoryId
        var productsByCategory = products.GroupBy(p => p.CategoryId);

        Console.WriteLine("Products Grouped by Category:");
        foreach (var categoryGroup in productsByCategory)
        {
            Console.WriteLine($"Category ID: {categoryGroup.Key}");
            foreach (var product in categoryGroup)
            {
                Console.WriteLine($"- {product.Name} (${product.Price})");
            }
        }
    }
}

Expected Output:
Products Grouped by Category:
Category ID: 1
- Laptop ($1200.00)
- Keyboard ($75.00)
- Mouse ($25.00)
Category ID: 2
- Monitor ($300.00)
- Webcam ($50.00)

Projections (Select)

Transform elements from one type to another using the Select extension method.


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

public class Product // Assuming Product class is defined as above
{
    public int Id { get; set; }
    public string Name { get; set; }
    public decimal Price { get; set; }
    public int CategoryId { get; set; }
}

public class Sample4
{
    public static void Main(string[] args)
    {
        var products = new List
        {
            new Product { Id = 1, Name = "Laptop", Price = 1200.00m, CategoryId = 1 },
            new Product { Id = 2, Name = "Keyboard", Price = 75.00m, CategoryId = 1 },
            new Product { Id = 3, Name = "Mouse", Price = 25.00m, CategoryId = 1 }
        };

        // Create an anonymous type with just the product name and price
        var productInfo = products.Select(p => new { p.Name, p.Price });

        Console.WriteLine("Product Names and Prices:");
        foreach (var item in productInfo)
        {
            Console.WriteLine($"- {item.Name}: ${item.Price}");
        }
    }
}

Expected Output:
Product Names and Prices:
- Laptop: $1200.00
- Keyboard: $75.00
- Mouse: $25.00

Set Operations (Distinct, Union, Intersect, Except)

Perform set operations on collections like finding unique elements, combining, finding common, or differing elements.


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

public class Sample5
{
    public static void Main(string[] args)
    {
        var numbers1 = new List { 1, 2, 3, 4, 5, 5 };
        var numbers2 = new List { 4, 5, 6, 7, 8 };

        // Distinct elements from numbers1
        var distinctNumbers = numbers1.Distinct();
        Console.WriteLine("Distinct Numbers from List 1: " + string.Join(", ", distinctNumbers)); // Output: 1, 2, 3, 4, 5

        // Union of numbers1 and numbers2
        var unionNumbers = numbers1.Union(numbers2);
        Console.WriteLine("Union of List 1 and List 2: " + string.Join(", ", unionNumbers)); // Output: 1, 2, 3, 4, 5, 6, 7, 8

        // Intersect of numbers1 and numbers2
        var intersectNumbers = numbers1.Intersect(numbers2);
        Console.WriteLine("Intersection of List 1 and List 2: " + string.Join(", ", intersectNumbers)); // Output: 4, 5

        // Except of numbers1 from numbers2 (elements in numbers2 not in numbers1)
        var exceptNumbers = numbers2.Except(numbers1);
        Console.WriteLine("Elements in List 2 not in List 1: " + string.Join(", ", exceptNumbers)); // Output: 6, 7, 8
    }
}

Expected Output:
Distinct Numbers from List 1: 1, 2, 3, 4, 5
Union of List 1 and List 2: 1, 2, 3, 4, 5, 6, 7, 8
Intersection of List 1 and List 2: 4, 5
Elements in List 2 not in List 1: 6, 7, 8