Prerequists

[thenirmalprajapati]

Type of issue

Missing information

Description

Add the line that,
Feature 'collection expressions' is not available in C# 7.3. Please use language version 12.0 or greater. LINQ

Page URL

https://learn.microsoft.com/en-us/dotnet/csharp/linq/store-the-results-of-a-query-in-memory

Content source URL

https://github.com/dotnet/docs/blob/main/docs/csharp/linq/store-the-results-of-a-query-in-memory.md

Document Version Independent Id

250d1850-1c0b-dc6c-44c1-5576ebadc8e3

Article author

@BillWagner

Metadata

• ID: f8951007-e0ed-32c4-e334-86ff154a518f
• Service: dotnet-csharp
• Sub-service: csharp-linq

[rextor92]

You can rewrite this as ...
List<int> numbers = new List<int>() { 1, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20 };

What you're seeing there is a collection expression which got introduced in .NET 8 with C# language version 12. If you're running C#7.3, I guess we're talking about a .NET Standard 2.0 project. Reference - C# Language Versions
You don't need to update the project to .NET 8 - if you're using .NET Standard 2.0 you need .NET Framework compatibility. However, simply having the .NET 8 SDKs installed will allow you to target the latest language version - just edit your .csproj file

<PropertyGroup>
  <TargetFramework>netstandard2.0</TargetFramework>
  <LangVersion>default</LangVersion>
</PropertyGroup>

Whether it is needed to call this out on the page, I'll leave to Bill. Personally, I think CS8370 and related errors are verbose enough.

[adamsitnik]

cc @eiriktsarpalis

[BillWagner]

I've been debating if we should update the doc to point out that collection expressions are in C# 12.

On one hand, collection expressions are one of the most useful C# 12 features. We want .NET developers to see examples that use them. Ideally, that can drive more adoption of the latest versions.

On the other hand, yes, it means samples that use them don't work on older versions.

I've been leaving them in place, without stating that they are a C# 12 feature. I've had some feedback, but not much.

I'm adding the discussion label to get other opinions.