csharplang/Language-Version-History.md

Features Added in C# Language Versions

C# 1.0 (Visual Studio.NET)

• Classes
• Structs
• Interfaces
• Events
• Properties
• Delegates
• Expressions
• Statements
• Attributes
• Literals

C# 2 (VS 2005)

• Generics
• Partial types
• Anonymous methods
• Iterators
• Nullable types
• Getter/setter separate accessibility
• Method group conversions (delegates)
• Static classes
• Delegate inference

C# 3 (VS 2008)

• Implicitly typed local variables
• Object and collection initializers
• Auto-Implemented properties
• Anonymous types
• Extension methods
• Query expressions
• Lambda expression
• Expression trees
• Partial methods

C# 4 (VS 2010)

• Dynamic binding
• Named and optional arguments
• Co- and Contra-variance for generic delegates and interfaces
• Embedded interop types ("NoPIA")

C# 5 (VS 2012)

• Asynchronous methods
• Caller info attributes

C# 6 (VS 2015)

• Draft Specification online
• Compiler-as-a-service (Roslyn)
• Import of static type members into namespace
• Exception filters
• Await in catch/finally blocks
• Auto property initializers
• Default values for getter-only properties
• Expression-bodied members
• Null propagator (null-conditional operator, succinct null checking)
• String interpolation
• nameof operator
• Dictionary initializer

C# 7.0 (Visual Studio 2017)

• Out variables
• Pattern matching
• Tuples
• Deconstruction
• Discards
• Local Functions
• Binary Literals
• Digit Separators
• Ref returns and locals
• Generalized async return types
• More expression-bodied members
• Throw expressions

C# 7.1 (Visual Studio 2017 version 15.3)

• Async main
• Default expressions
• Reference assemblies
• Inferred tuple element names
• Pattern-matching with generics

C# 7.2 (Visual Studio 2017 version 15.5)

• Span and ref-like types
• In parameters and readonly references
• Ref conditional
• Non-trailing named arguments
• Private protected accessibility
• Digit separator after base specifier

C# 7.3 (Visual Studio 2017 version 15.7)

• System.Enum, System.Delegate and unmanaged constraints.
• Ref local re-assignment: Ref locals and ref parameters can now be reassigned with the ref assignment operator (= ref).
• Stackalloc initializers: Stack-allocated arrays can now be initialized, e.g. Span<int> x = stackalloc[] { 1, 2, 3 };.
• Indexing movable fixed buffers: Fixed buffers can be indexed into without first being pinned.
• Custom fixed statement: Types that implement a suitable GetPinnableReference can be used in a fixed statement.
• Improved overload candidates: Some overload resolution candidates can be ruled out early, thus reducing ambiguities.
• Expression variables in initializers and queries: Expression variables like out var and pattern variables are allowed in field initializers, constructor initializers and LINQ queries.
• Tuple comparison: Tuples can now be compared with == and !=.
• Attributes on backing fields: Allows [field: …] attributes on an auto-implemented property to target its backing field.