4 ways to enable the latest C# features

C# evolves regularly. C# 7.1 is available starting with Visual Studio 2017 Update 3 (version 15.3). However, its new features are not enabled by default; the compiler uses the latest major version (currently 7.0). You must explicitly configure your project to opt in to a newer language version.

If you're curious about what's new in C# 7.1, the proposals are available on GitHub:

• Async Main
• Default Expressions
• Infer tuple names
• Pattern-matching with generics

#Method 1: Using the Light bulb

This is the simplest approach. Just use a new language feature in your code. Visual Studio will automatically detect it and prompt you to upgrade the project's language version:

Enabling C# features using lightbulb

#Method 2: Using the project settings window

1. Open the settings of your project
2. Select the Build tab
3. Click the Advanced button
4. Select the version you want

Enabling C# features using project properties

#Method 3: Editing the csproj

You can edit the csproj file directly, and add <LangVersion>latest</LangVersion> or the explicit version <LangVersion>7.1</LangVersion>:

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <RootNamespace>ConsoleApp1</RootNamespace>
    <AssemblyName>ConsoleApp1</AssemblyName>
    <TargetFrameworkVersion>v4.7</TargetFrameworkVersion>
    <FileAlignment>512</FileAlignment>
    <AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>
    <LangVersion>latest</LangVersion>
  </PropertyGroup>

#Method 4: Using a prop file

If you want to set the language version for all your projects at once, create a file named Directory.Build.props at the root of your repository. This file defines common properties shared across your projects:

<Project>
  <PropertyGroup>
    <LangVersion>latest</LangVersion>
  </PropertyGroup>
</Project>

MSBuild merges your .csproj files with the props file, so the LangVersion setting applies automatically to all existing and new projects in your solution. You can also use this file to configure shared properties such as the author, company, or project URL. See an example here: Directory.Build.props

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