Configure C# language version

If you must specify your C# version explicitly, you can do so in several ways:

• Manually edit the project file.
• Set the language version for multiple projects in a subdirectory.
• Configure the LangVersion compiler option.

Tip

You can see the language version in Visual Studio in the project properties page. Under the Build tab, the Advanced pane displays the version selected.

To know what language version you're currently using, put #error version (case sensitive) in your code. This makes the compiler report a compiler error, CS8304, with a message containing the compiler version being used and the current selected language version. See #error (C# Reference) for more information.

Edit the project file

You can set the language version in your project file. For example, if you explicitly want access to preview features, add an element like this:

<PropertyGroup>
   <LangVersion>preview</LangVersion>
</PropertyGroup>

The value preview uses the latest available preview C# language version that your compiler supports.

Configure multiple projects

To configure multiple projects, you can create a Directory.Build.props file, typically in your solution directory, that contains the <LangVersion> element. Add the following setting to the Directory.Build.props file:

<Project>
 <PropertyGroup>
   <LangVersion>preview</LangVersion>
 </PropertyGroup>
</Project>

Builds in all subdirectories of the directory containing that file now use the preview C# version. For more information, see Customize your build.