What are the correct version numbers for C#?

Question

What are the correct version numbers for C#? What came out when? Why can\'t I find any answers about C# 3.5?

This question is primarily to

Answer 1

C# Version History:

C# is a simple and powerful object-oriented programming language developed by Microsoft.

C# has evolved much since its first release in 2002. C# was introduced with .NET Framework 1.0.

The following table lists important features introduced in each version of C#.

And the latest version of C# is available in C# Versions.

1:

Answer 2

C# 1.0 - Visual Studio .NET 2002

Classes
Structs
Interfaces
Events
Properties
Delegates
Expressions
Statements
Attributes
Literals

C# 1.2 - Visual Studio .NET 2003

Dispose in foreach
foreach over string specialization
C# 2 - Visual Studio 2005
Generics
Partial types
Anonymous methods
Iterators
Nullable types
Getter/setter separate accessibility
Method group conversions (delegates)
Static classes
Delegate inference

C# 3 - Visual Studio 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 - Visual Studio 2010

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

C# 5 - Visual Studio 2012

    Asynchronous methods
    Caller info attributes

C# 6 - Visual Studio 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.

C# 8.0 - .NET Core 3.0 and Visual Studio 2019 version 16.3

Nullable reference types: express nullability intent on reference types with ?, notnull constraint and annotations attributes in APIs, the compiler will use those to try and detect possible null values being dereferenced or passed to unsuitable APIs.
Default interface members: interfaces can now have members with default implementations, as well as static/private/protected/internal members except for state (ie. no fields).
Recursive patterns: positional and property patterns allow testing deeper into an object, and switch expressions allow for testing multiple patterns and producing corresponding results in a compact fashion.
Async streams: await foreach and await using allow for asynchronous enumeration and disposal of IAsyncEnumerable<T> collections and IAsyncDisposable resources, and async-iterator methods allow convenient implementation of such asynchronous streams.
Enhanced using: a using declaration is added with an implicit scope and using statements and declarations allow disposal of ref structs using a pattern.
Ranges and indexes: the i..j syntax allows constructing System.Range instances, the ^k syntax allows constructing System.Index instances, and those can be used to index/slice collections.
Null-coalescing assignment: ??= allows conditionally assigning when the value is null.
Static local functions: local functions modified with static cannot capture this or local variables, and local function parameters now shadow locals in parent scopes.
Unmanaged generic structs: generic struct types that only have unmanaged fields are now considered unmanaged (ie. they satisfy the unmanaged constraint).
Readonly members: individual members can now be marked as readonly to indicate and enforce that they do not modify instance state.
Stackalloc in nested contexts: stackalloc expressions are now allowed in more expression contexts.
Alternative interpolated verbatim strings: @$"..." strings are recognized as interpolated verbatim strings just like $@"...".
Obsolete on property accessors: property accessors can now be individually marked as obsolete.
Permit t is null on unconstrained type parameter

[source] : https://github.com/dotnet/csharplang/blob/master/Language-Version-History.md

Answer 3

Comparing the MSDN articles "What's New in the C# 2.0 Language and Compiler" and "What's New in Visual C# 2005", it is possible to deduce that "C# major_version.minor_version" is coined according to the compiler's version numbering.

There is C# 1.2 corresponding to .NET 1.1 and VS 2003 and also named as Visual C# .NET 2003.

But further on Microsoft stopped to increment the minor version (after the dot) numbers or to have them other than zero, 0. Though it should be noted that C# corresponding to .NET 3.5 is named in msdn.microsoft.com as "Visual C# 2008 Service Pack 1".

There are two parallel namings: By major .NET/compiler version numbering and by Visual Studio numbering.

C# 2.0 is a synonym for Visual C# 2005

C# 3.0 corresponds (or, more correctly, can target) to:

• .NET 2.0 <==> Visual C# 2005
• .NET3.0 <==> Visual C# 2008
• .NET 3.5 <==> Visual C# 2008 Service Pack 1

Answer 4

Version     .NET Framework  Visual Studio   Important Features
C# 1.0  .NET Framework 1.0/1.1  Visual Studio .NET 2002     

    Basic features

C# 2.0  .NET Framework 2.0  Visual Studio 2005  

    Generics
    Partial types
    Anonymous methods
    Iterators
    Nullable types
    Private setters (properties)
    Method group conversions (delegates)
    Covariance and Contra-variance
    Static classes

C# 3.0  .NET Framework 3.0\3.5  Visual Studio 2008  

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

C# 4.0  .NET Framework 4.0  Visual Studio 2010  

    Dynamic binding (late binding)
    Named and optional arguments
    Generic co- and contravariance
    Embedded interop types

C# 5.0  .NET Framework 4.5  Visual Studio 2012/2013     

    Async features
    Caller information

C# 6.0  .NET Framework 4.6  Visual Studio 2013/2015     

    Expression Bodied Methods
    Auto-property initializer
    nameof Expression
    Primary constructor
    Await in catch block
    Exception Filter
    String Interpolation

C# 7.0  .NET Core 2.0   Visual Studio 2017  

    out variables
    Tuples
    Discards
    Pattern Matching
    Local functions
    Generalized async return types
    Numeric literal syntax improvements
C# 8.0  .NET Core 3.0   Visual Studio 2019  

    
    Readonly members
    Default interface methods
    Pattern matching enhancements:
        Switch expressions
        Property patterns
        Tuple patterns
        Positional patterns
    Using declarations
    Static local functions
    Disposable ref structs
    Nullable reference types
    Asynchronous streams
    Asynchronous disposable
    Indices and ranges
    Null-coalescing assignment
    Unmanaged constructed types
    Stackalloc in nested expressions
    Enhancement of interpolated verbatim strings

Answer 5

C# language version history:

These are the versions of C# known about at the time of this writing:

• C# 1.0 released with .NET 1.0 and VS2002 (January 2002)
• C# 1.2 (bizarrely enough); released with .NET 1.1 and VS2003 (April 2003). First version to call Dispose on IEnumerators which implemented IDisposable. A few other small features.
• C# 2.0 released with .NET 2.0 and VS2005 (November 2005). Major new features: generics, anonymous methods, nullable types, iterator blocks
• C# 3.0 released with .NET 3.5 and VS2008 (November 2007). Major new features: lambda expressions, extension methods, expression trees, anonymous types, implicit typing (var), query expressions
• C# 4.0 released with .NET 4 and VS2010 (April 2010). Major new features: late binding (dynamic), delegate and interface generic variance, more COM support, named arguments, tuple data type and optional parameters
• C# 5.0 released with .NET 4.5 and VS2012 (August 2012). Major features: async programming, caller info attributes. Breaking change: loop variable closure.
• C# 6.0 released with .NET 4.6 and VS2015 (July 2015). Implemented by Roslyn. Features: initializers for automatically implemented properties, using directives to import static members, exception filters, element initializers, await in catch and finally, extension Add methods in collection initializers.
• C# 7.0 released with .NET 4.7 and VS2017 (March 2017). Major new features: tuples, ref locals and ref return, pattern matching (including pattern-based switch statements), inline out parameter declarations, local functions, binary literals, digit separators, and arbitrary async returns.
• C# 7.1 released with VS2017 v15.3 (August 2017) New features: async main, tuple member name inference, default expression, pattern matching with generics.
• C# 7.2 released with VS2017 v15.5 (November 2017) New features: private protected access modifier, Span<T>, aka interior pointer, aka stackonly struct, everything else.
• C# 7.3 released with VS2017 v15.7 (May 2018). New features: enum, delegate and unmanaged generic type constraints. ref reassignment. Unsafe improvements: stackalloc initialization, unpinned indexed fixed buffers, custom fixed statements. Improved overloading resolution. Expression variables in initializers and queries. == and != defined for tuples. Auto-properties' backing fields can now be targeted by attributes.
• C# 8.0 released with .Net Core 3.0 and VS2019 v16.3 (September 2019). Major new features: nullable reference-types, Asynchronous streams, Indices and Ranges, Readonly members, using declarations,default interface methods, Static local functions and Enhancement of interpolated verbatim strings.
• C# 9.0 released with .Net 5.0 and VS2019 v16.8 (November 2020). Major new features: init-only properties, records, with-expressions, data classes, positional records, top-level programs, improved pattern matching (simple type patterns, relational patterns, logical patterns), improved target typing (target-type new expressions, target typed ?? and ?), covariant returns. Minor features: relax ordering of ref and partial modifiers, parameter null checking, lambda discard parameters, native ints, attributes on local functions, function pointers, static lambdas, extension GetEnumerator, module initializers, extending partial.

In response to the OP's question:

What are the correct version numbers for C#? What came out when? Why can't I find any answers about C# 3.5?

There is no such thing as C# 3.5 - the cause of confusion here is that the C# 3.0 is present in .NET 3.5. The language and framework are versioned independently, however - as is the CLR, which is at version 2.0 for .NET 2.0 through 3.5, .NET 4 introducing CLR 4.0, service packs notwithstanding. The CLR in .NET 4.5 has various improvements, but the versioning is unclear: in some places it may be referred to as CLR 4.5 (this MSDN page used to refer to it that way, for example), but the Environment.Version property still reports 4.0.xxx.

As of May 3, 2017, the C# Language Team created a history of C# versions and features on their GitHub repository: Features Added in C# Language Versions. There is also a page that tracks upcoming and recently implemented language features.

Answer 6

You can check the latest C# versions here