.netframework update difficulties

Question

I wanted to use new(), but it's only allowed in 4.9. So i downloaded latest sdk, but i still can't change to 4.9. my highest version possible right now is 4.8.

Answer 1

The minimal requirement for using new() is Visual Studio 2019 setup for C#9. When creating a new project in VS2019 the default Framework is .NET Core 5. To get to C#9, double click the project file in solution explorer and make sure LangVersion as shown below. If you use latest rather than 9 and have .NET 5 and 6, this will not work unless you enable experimental features and even so there are complications so use 9 for LangVersion.

Note if you go to VS2022 you can not build for x86, only x64.

<Project Sdk="Microsoft.NET.Sdk">  
  
  <PropertyGroup>  
	  <LangVersion>9.0</LangVersion>  
	  <TargetFramework>net5.0</TargetFramework>  
  </PropertyGroup>  
  
</Project>  

If using windows forms, <TargetFramework>net5.0-windows</TargetFramework>

Answer 2

It seems that target-typed new expressions is offered in C# 9, which is available in .NET 5 (also named “Core”), but not in .NET Framework. Try using Visual Studio 2022. Create a “Console App” project instead of “Console App (.NET Framework)”. Specify .NET 5 or 6. (Maybe it works in Visual Studio 2019 too).