Home

C# Version History

Explore the evolution of C# language features

C#

Language Evolution

v15

2026Preview

Collection expression arguments Union Types closed Extension indexers

v14

2025

The field keyword Implicit span conversions nameof with unbound generic types Null conditional assignment partial events and constructors Extension members

v13

2024

params collections New lock object Overload resolution priority

v12

2023

Primary constructors Collection expressions Default parameters in lambdas ref readonly parameters

v11

2022

Generic Math Auto-default structs Required members Newlines in string interpolation expressions List patterns

v10

2021

Record structs Interpolated string handlers global using directive File-scoped namespace declaration Const interpolated strings CallerArgumentExpression attribute Extended property patterns

v9.0

2020

Records Init-only setters Top-level statements Pattern matching enhancements

v8.0

2019

readonly members default interface methods Nullable reference types Asynchronous streams Indices and Ranges Null-coalescing assignment

v7.0

2017

out variables Tuples and deconstruction Pattern matching

v6.0

2015

Static imports Exception filters nameof operator string interpolation Null propagator Auto-property initializers

v5.0

2012

Asynchronous members Caller info attributes

v4.0

2010

Dynamic binding Named/optional parameters Generic covariant/contravariant

v3.0

2007

Auto-implemented properties Anonymous types Lambda expressions Expression trees Extension methods Partial methods Object and collection initializers

v2.0

2005

generics partial types anonymous lambdas Nullable value types Iterators Covariance / Contravariance

v1.0

2002

classes structs interfaces properties events delegates Operators and expressions