Question How do I upgrade to C# 8?

[glasswizzard]

I figured you just download the latest VS and that's it, you've got the latest version of C#, but today I got an error when trying to set a property to readonly, saying "Feature 'readonly members' is not availble in C# 7.3. Please use language version 8.0 or greater."

So it seems I'm using version 7.3, how do I upgrade?
Thanks

 

[JohnH]

The history of C# - C# Guide - C#

Learn how the C# language has changed over its many releases. Learn when different features were introduced in the language.

docs.microsoft.com

C# 8.0 is supported on .NET Core 3.x and .NET Standard 2.1. For more information, see C# language versioning.

Relevant for you?

 

[glasswizzard]

I see, so VS uses .NET Core 2 by default and I need to upgrade to .NET Core 3.

I have VS version 16.4.5, .NET Core 3 should be installed with this version. I don't get any option to choose which version of .NET Core to use when starting a new project though. How do I change to .NET Core 3? If I started a project with .NET Core 2 can that project be updated to use .NET core 3?

 

[jmcilhinney]

Is there an option to change the .NET Core version in the project properties?

 

[jmcilhinney]

I just created a C# Console App project in VS 16.4.5 and it defaulted to .NET Core 3.1. The Application page of the project properties has a drop-down for Target framework so you should be able to upgrade projects targeting older versions there.

 

[glasswizzard]

A console app does indeed default to .NET Core 3.1.

Aren't WPF apps supposed to do that too? If not does that mean that WPF apps can't use C# 8 yet?

 

[jmcilhinney]

I just created a WPF App project and it defaulted to .NET Core 3.1 (3.0 was the only other option in the properties, as you'd expect) and I was able to add readonly members to a structure, so it must be using C# 8.0. If you have a project that was created using C# 7.3 then I'm not sure where that is specified and/or whether it can be changed. If you want to do so, maybe creating a new project and importing existing items would be your best bet. Seems odd so maybe I'm missing something... or you are.

 

[glasswizzard]

It's definitely me that was missing something, I've been starting new WPF projects using .NET Framework, not .Net Core. Problem solved

 

[NoUserHere]

Be warned, if you go up to the very latest C# version, there is no going back and you will be required to create a new project should you wish to not use the latest C# features. In my case, I am already using them, and so I can not downgrade this project to use a previous version. Nor can you edit any of the project files to reflect other versions. There is a strange bug which I reported to Microsoft regarding being locked into a specific version of C# once you upgrade your project, you can no longer downgrade a version. Hence the warning of not being able to select a different version. I don't recall how I got around this before to allow me to change C# versions, perhaps @Skydiver recalls what I did when I had this issue before.