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20180920
C# Version

ref:
https://docs.microsoft.com/en-us/dotnet/csharp/whats-new/index#previous-versions

To use the latest features in a point release, you need to configure the compiler language version and select the version.
•C# 7.3:◦This page describes the latest features in the C# language. C# 7.3 is currently available in Visual Studio 2017 version 15.7, and in the .NET Core 2.1 SDK 2.1.300 RC1.

•C# 7.2:◦This page describes the features added in the C# language. C# 7.2 is currently available in Visual Studio 2017 version 15.5, and in the .NET Core 2.0 SDK.

•C# 7.1:◦This page describes the features added in C# 7.1. These features were added in Visual Studio 2017 version 15.3, and in the .NET Core 2.0 SDK.

•C# 7.0:◦This page describes the features added in C# 7.0. These features were added in Visual Studio 2017 and .NET Core 1.0 and later

•C# 6:◦This page describes the features that were added in C# 6. These features are available in Visual Studio 2015 for Windows developers, and on .NET Core 1.0 for developers exploring C# on macOS and Linux.

•Cross Platform Support:◦C#, through .NET Core support, runs on multiple platforms. If you are interested in trying C# on macOS, or on one of the many supported Linux distributions, learn more about .NET Core.

•.NET Compiler Platform SDK:◦The .NET Compiler Platform SDK enables you to write code that performs static analysis on C# code. You can use these APIs to find potential errors, or bad practices, suggest fixes, and even implement those fixes.


Previous Versions

The following lists key features that were introduced in previous versions of the C# language and Visual Studio .NET.
•Visual Studio .NET 2013:◦This version of Visual Studio included bug fixes, performance improvements, and technology previews of .NET Compiler Platform ("Roslyn") which became the .NET Compiler Platform SDK.

•C# 5, Visual Studio .NET 2012:◦Async / await, and caller information attributes.

•C# 4, Visual Studio .NET 2010:◦Dynamic, named arguments, optional parameters, and generic covariance and contra variance.

•C# 3, Visual Studio .NET 2008:◦Object and collection initializers, lambda expressions, extension methods, anonymous types, automatic properties, local var type inference, and Language Integrated Query (LINQ).

•C# 2, Visual Studio .NET 2005:◦Anonymous methods, generics, nullable types, iterators/yield, static classes, and covariance and contra variance for delegates.

•C# 1.1, Visual Studio .NET 2003:◦#line pragma and xml doc comments.

•C# 1, Visual Studio .NET 2002:◦The first release of C#.