c#-8.0

问题 When working with an IEnumerable<T> there are the build-in extension methods from the System.Linq namespace such as Skip , Where and Select to work with. When Microsoft added IAsyncEnumerable in C#8 did they also add new Linq methods to support this? I could of course implement these methods myself, or maybe find some package which does that, but I'd prefer to use a language-standard method if it exists. 回答1: There is, in the System.Linq.Async namespace from the System.Reactive package. If

问题 Today while coding, visual studio notified me that my switch case could be optimized. But the code that I had vs the code that visual studio generated from my switch case does not result in the same outcome. The Enum I Used: public enum State { ExampleA, ExampleB, ExampleC }; After the following code runs the value is equal to 2147483647. State stateExample = State.ExampleB; double value; switch (stateExample) { case State.ExampleA: value = BitConverter.ToSingle(BitConverter.GetBytes((long

问题 I am going through C# 9 new features which will be released soon. Init-Only properties are being introduced with it. The one big limitation today is that the properties have to be mutable for object initializers to work: They function by first calling the object’s constructor (the default, parameterless one in this case) and then assigning to the property setters. Init-only properties fix that! They introduce an init accessor that is a variant of the set accessor which can only be called

问题 For one of our projects we're trying to upgrade to use C#8 instead of C#7.1. The upgrade looks like it works, because the compiler looks like it takes C#8 statements (it doesn't mark it as an error). However, when I build the project I get a build failed without any errors showing initially. The code to test C#8 is of the following lines: private string TestCSharp8(int x) { return x switch { 0 => "ZERO", 1 => "ONE", 2 => "TWO", 3 => "THREE", _ => "OTHER" }; } The IDE is accepting this code

问题 For one of our projects we're trying to upgrade to use C#8 instead of C#7.1. The upgrade looks like it works, because the compiler looks like it takes C#8 statements (it doesn't mark it as an error). However, when I build the project I get a build failed without any errors showing initially. The code to test C#8 is of the following lines: private string TestCSharp8(int x) { return x switch { 0 => "ZERO", 1 => "ONE", 2 => "TWO", 3 => "THREE", _ => "OTHER" }; } The IDE is accepting this code

问题 I have a .net core 3.1 console app. I have a method with the following signature: public async IAsyncEnumerable<string> GetFilePathsFromRelativePathAsync(string relativePath) If I call it: private async Task<IEnumerable<FileUpload>> GetFileUploadsAsync(string relativePath) { ... var filePaths = await service.GetFilePathsFromRelativePathAsync(relativePath); ... } I get the following error: Error CS1061 'IAsyncEnumerable' does not contain a definition for 'GetAwaiter' and no accessible

问题 This question already has answers here : Default Interface Methods. What is deep meaningful difference now, between abstract class and interface? [closed] (6 answers) Closed 10 months ago . C# 8.0 has introduced a new language feature – default implementations of interface members. public interface IRobot { void Talk(string message) { Debug.WriteLine(message); } } The new default interface implementations provides the elements of the traits language. However is is also blurring the line

问题 This question already has answers here : Default Interface Methods. What is deep meaningful difference now, between abstract class and interface? [closed] (6 answers) Closed 10 months ago . C# 8.0 has introduced a new language feature – default implementations of interface members. public interface IRobot { void Talk(string message) { Debug.WriteLine(message); } } The new default interface implementations provides the elements of the traits language. However is is also blurring the line

问题 Closed . This question is opinion-based. It is not currently accepting answers. Want to improve this question? Update the question so it can be answered with facts and citations by editing this post. Closed 4 months ago . Improve this question So in C# 8 interfaces will be able to have actual implementations of methods. At that point, what will be the difference between abstract classes and interfaces and why would I ever use abstract class anymore?What would be the advantage of this change

问题 Is there a way to make the analyzer understand that the variable Bar has a value for the following case? #nullable enable class Foo { bool GenerateArray => Bar.HasValue; int? Bar { get; set; } void FooBar() { var data = (GenerateArray) ? new int[Bar.Value] : null; } } There is the warning "Nullable value type may be null." for Bar.Value but it obviously can't be. I am aware of two ways to avoid the warning. Both have disadvantages: Using Bar.HasValue directly instead of the property