Getting Setup With .NET Core 3 Preview and C# 8

I’ve previously done posts on how to setup both .NET Core 2.1 and .NET Core 2.2. The reason for these posts was because it was still a little shaky exactly which version of the SDK you needed to actually build for these platforms. e.x. If you had .NET Core SDK 2.1, it didn’t actually mean you could build .NET Core 2.1 projects (How infuriating is that?!).

But things have gotten better and now it’s usually just a matter of installing the latest SDK and away you go, so there isn’t really much I could normally write for each version bump. However! .NET Core 3 includes a couple of really important updates that I want to talk about in the future. Windows Forms/WPF development on top of .NET Core, and C# 8. Because of this, I wanted to have a post all written up on setting up your machine for .NET Core 3 development while things are in preview so I don’t have to repeat myself every future post!

Installing the .NET Core 3 Preview SDK

Installing the .NET Core 3 SDK is fairly straight forward. Just head to the download page and grab the SDK (Not the runtime) and install! You do want to ensure you are on the .NET Core 3 page and not the general download page of .NET Core as the current “live” version is 2.2 not 3.

Once installed, you should be able to open a command prompt and run  dotnet --info with the output being something close to :

Of course as long as the version is 3+, you should be good to go.

It’s also important to note that your default SDK on your machine will now be 3 and not 2.2 (Or the previous version you had installed). If you have existing projects that are using this SDK version, you will need to create a new global.json file to be able to run different SDK’s side by side. Luckily there is a great guide on how to do this right here!

Using VS Code

If you like programming in VS Code, then you’re actually good to write .NET Core 3 code right from the get go (Since it’s just a text editor). Obviously you will want to install the “C#” extension if you want all the good intellisense (Including for C# 8 new types), but other than that because builds are all from the command line there isn’t too much to it.

If you want to use C# 8 features in VS Code, see that section of this article below (It’s the same for Visual Studio or VS Code).

Using Visual Studio

A preview version of .NET Core also has a preview version of Visual Studio to accompany it. This can be a little annoying because it’s not just jumping on the “preview” update track for your existing Visual Studio installation, you actually need to download and install a completely new version of Visual Studio. This means another ~6GB of space taken up with a VS version you may use once or twice to try out new features.

I feel the need to point this out because it caught me out initially. The first version of Visual Studio to support .NET Core 3.0 is Visual Studio 2019 Preview 1. Emphasise on the 2019 part because I was wondering why my 2017 preview Visual Studio wasn’t working at first!

You can grab the preview version of Visual Studio here : https://visualstudio.microsoft.com/vs/preview/

I have actually dabbled with a solo installation of the preview version only and not bothered with the current release version. Theoretically it could have a few more bugs in it than the current supported release, but so far so good!

Enabling C# 8 Features

We can enable C# 8 on a project by project basis by editing our .csproj files. Simply open up your project file, and add the following anywhere within your <Project> node :

And that’s literally it (Too easy!).

Some people get trapped thinking that the following will enable C# 8 features :

But remember, version 8 of the language is in preview too. Latest refers to the latest minor version that has actually been released (So at this time, 7.3). If you try and use new features of C# 8, for example the “Range” type, you will get an error like so :

error CS8370: Feature ‘range operator’ is not available in C# 7.3. Please use language version 8.0 or greater.

But other than that, everything is pretty straight forward! Now go ahead and start using Range, AsyncEnumerable, Indices and Nullable Reference Types!

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