c#-6.0

问题 Why this c# code throws a null exception? bool boolResult = SomeClass?.NullableProperty.ItsOkProperty ?? false; Isn´t elvis operator supposed to stop evaluation (short circuit) once the NullableProperty evaluates to null? In my understanding the line of code above is a shortcut for: bool boolResult if(SomeClass != null) if(SomeClass.NullableProperty != null) boolResult = SomeClass.NullableProperty.ItsOkProperty; else boolResult = false; else boolResult = false; Did I assume wrong? EDIT: Now I

问题 Is there analog of [DebuggerStepThrough] attribute available for expression-bodied properties in C# ? For example I want to skip over the code public Byte ByteArray => Builder.CreateArray(); [DebuggerStepThrough] can not be applied to properties. Does C# team provide any other solution in C# 6.0 ? 回答1: DebuggerStepThrough isn't valid for expression bodied properties as this: [DebuggerStepThrough] public Byte ByteArray => Builder.CreateArray(); Doesn't compile. This however does: public Byte

问题 I've looked around a bit but haven't been able to find an answer to how the new C# 6.0 compiler breaks down the new null propagation command for something such as the following: BaseType myObj = new DerivedType(); string myString = (myObj as DerivedType)?.DerivedSpecificProperty; What I want to know is how exactly it handles this. Does it cache the as cast into a new DerivedType variable (i.e., this is just syntactical sugar for an as cast followed by an null comparison). Or if it actually as

问题 In MVC 6 source code I saw some code lines that has strings leading with $ signs. As I never saw it before, I think it is new in C# 6.0. I'm not sure. (I hope I'm right, otherwise I'd be shocked as I never crossed it before. It was like: var path = $"'{pathRelative}'"; 回答1: You're correct, this is a new C# 6 feature. The $ sign before a string enables string interpolation. The compiler will parse the string specially, and any expressions inside curly braces will be evaluated and inserted into

问题 What is the difference between a property with a omitted setter and a property with a private setter? public string Foo { get; private set; } vs public string Foo { get; } 回答1: In C# 6, get; only properties are only settable from the constructor. From everywhere else, it is read-only. A property with a private set; can be set from everywhere inside that class. 回答2: From outside the class, it won't change anything if you use this syntax: public string Foo { get; } But you won't be able to

问题 With C# 6.0 I can do this var isEqual = x.Id == y.Id && x.UpdatedAt == y.UpdatedAt && x.Name == y.Name && x.RulesUrl == y.RulesUrl && x.OngoingChallenges?.Count == y.OngoingChallenges?.Count && x.MembershipIds?.Count == y.MembershipIds?.Count; Is there any nice solution to do this with C# < 6.0? I mean this part && x.OngoingChallenges?.Count == y.OngoingChallenges?.Count && x.MembershipIds?.Count == y.MembershipIds?.Count; Because in old projects we do not have possibility to use C# 6.0. How

问题 Using expression-bodied members allows you to define the body of a method or property as a single expression without a return keyword (should it return something). For example it turns these int Method1() { return 5; } void Method2() { Console.WriteLine(); } into these int Method1() => 5; void Method2() => Console.WriteLine(); A difference comes into play when you throw an exception from the body: void Method3() { throw new Exception(); } However, the following will not compile: void Method3(

问题 It is a good idea to use nameof over expressions for extracting property names? //method with expression protected void RaisePropertyChanged<T>(Expression<Func<T>> propertyExpression, bool isValid, [param: Localizable(true)] string validationError) { string propertyName = PropertySupport.ExtractPropertyName(propertyExpression); RaisePropertyChanged(propertyName, isValid, validationError); } //the same logic without expression protected void RaisePropertyChanged(string propertyName, [param:

问题 Short and simple. Does the new string interpolation in C# 6.0 rely on reflection? I.e. does string myStr = $"Hi {name}, how are you?"; use reflection at runtime to find the variable "name" and its value? 回答1: No. It doesn't. It is completely based on compile-time evaluation. You can see that with this TryRoslyn example that compiles and decompiles this: int name = 4; string myStr = $"Hi {name}, how are you?"; Into this: int num = 4; string.Format("Hi {0}, how are you?", num); string

问题 This question already has answers here : Does C# 6.0 work for .NET 4.0? (5 answers) Closed 4 years ago . I have a project that targets older versions of the .NET framework (.NET 4.5.2). I installed Visual Studio 2015 (and therefore .NET 4.6 on my machine). I noticed that if I use C# language features released in .NET 4.6/C# 6, it still compiles. If my project's target framework is < .NET 4.6, shouldn't this not compile: public string MyExpressionBodyProperty => "1"; //auto properties are new