.NET API Documentation

System.Linq Namespace

Classes

• ⭐

  Enumerable

  Provides a set of static extension methods for LINQ that allow you to create queries against objects that implement IEnumerable<T>.

  public static class Enumerable
• ⭐

  Queryable

  Provides a set of static extension methods for LINQ that allow you to create queries against objects that implement IQueryable<T>.

  public static class Queryable

Interfaces

• 📜

  IOrderedEnumerable<TElement>

  Represents an ordered sequence of elements.

  public interface IOrderedEnumerable<TElement> : IEnumerable<TElement>, IEnumerable
• 📜

  IGrouping<TKey,TElement>

  Represents a group of elements that have a common key.

  public interface IGrouping<out TKey, out TElement> : IEnumerable<TElement>, IEnumerable

Common LINQ Operations

The System.Linq namespace enables powerful data querying capabilities in .NET. Some of the most common operations include:

• Filtering: Using methods like Where() to select elements that satisfy a condition.
• Projection: Using methods like Select() to transform elements into a new form.
• Ordering: Using methods like OrderBy() and OrderByDescending() to sort elements.
• Grouping: Using methods like GroupBy() to group elements by a key.
• Joining: Using methods like Join() and GroupJoin() to combine elements from different sequences.
• Aggregation: Using methods like Count(), Sum(), Average(), Min(), and Max() to compute aggregate values.

Example: Filtering and Selecting

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 class Example
{
    public static void Main(string[] args)
    {
        List<Product> products = new List<Product>
        {
            new Product { Id = 1, Name = "Laptop", Price = 1200.00m },
            new Product { Id = 2, Name = "Mouse", Price = 25.50m },
            new Product { Id = 3, Name = "Keyboard", Price = 75.00m },
            new Product { Id = 4, Name = "Monitor", Price = 300.00m }
        };

        // Get names of products with a price greater than 100.00
        var expensiveProductNames = products
            .Where(p => p.Price > 100.00m)
            .Select(p => p.Name);

        Console.WriteLine("Expensive Product Names:");
        foreach (var name in expensiveProductNames)
        {
            Console.WriteLine(name);
        }
    }
}