System.Linq in C#

System.Linq is a powerful namespace in C# that provides a range of standard query operators to perform filtering, projection, ordering, grouping, and other operations on collections of data.

LINQ Query Syntax

The most common way to use System.Linq is through LINQ query syntax, which allows you to write queries in a declarative syntax similar to SQL:

var result = from item in collection
             where item.Property == "Value"
             orderby item.Date descending
             select item;

Here, we declare a new variable result that contains the results of a LINQ query on a collection of items. The from keyword specifies the collection we want to query, and the where, orderby, and select keywords further refine the query.

Lambda Expressions

Another way to use System.Linq is through lambda expressions, which provide a more compact and functional programming approach:

var result = collection.Where(item => item.Property == "Value")
                       .OrderByDescending(item => item.Date)
                       .Select(item => item);

Here, we declare a new variable result that uses the Where, OrderByDescending, and Select extension methods from System.Linq to achieve the same result as the LINQ query syntax example.

Standard Query Operators

System.Linq provides a range of standard query operators, including:

• Filtering: Where, OfType, Take, Skip, Distinct
• Projection: Select, SelectMany
• Ordering: OrderBy, OrderByDescending, ThenBy, ThenByDescending
• Grouping: GroupBy, GroupJoin, Join
• Set operations: Union, Intersect, Except
• Aggregation: Count, Sum, Average, Min, Max

These operators allow you to easily perform complex operations on collections of any type, including arrays, lists, dictionaries, and more.

Conclusion

System.Linq is a powerful namespace in C# that provides a wide range of standard query operators for manipulating collections of data. By leveraging LINQ query syntax and lambda expressions, you can write concise and expressive code that is easy to read and maintain.