Liens

Switch expression

switch (i)
{
    case 1:
        return "One";
    default:
        throw new Exception("Invalid value");
}

i switch
{
    1 => "One",
    _ => throw new Exception("Invalid value")
};

Using declaration

using (var file = new StreamWriter("MyFile.txt"))
{
    // some code
} // file is disposed here

void MyMethod()
{
    using var file = new StreamWriter("MyFile.txt");
    // some code

    // file is disposed here, at the end of the enclosing scope
}

.NET Framework

The C# 8 / .NET Framework combination is not officially supported by Microsoft.
It can be forced by editing the csproj file.

MyProject.csproj

<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <PropertyGroup>
    <TargetFrameworkVersion>v4.7.2</TargetFrameworkVersion>
    <LangVersion>8.0</LangVersion>

default interface members won't work
ssynchronous streams and indices and ranges will need polyfill nuget package