There is no official support for any version of the. NET Core 3.1 or newer, latest versions of Xamarin and Mono, and potentially future versions of UWP and Unity. NET Standard 2.1 and compatible runtimes. Different from the previous versions of the language, the support for C# 8 wasn’t added to older. The option is only available for projects using C# 8 or a later version. In recent versions of Visual Studio 2019, the option is also available on the Build page of the Project Properties window:’’įigure 1: Nullable option on the Build page of the Project Properties window The following property must be added to the project file for that: An explicit opt-in is required for each project. To avoid such a breaking change in a new version of the language, the nullable reference types is the only feature of C# 8 that isn’t enabled by default. They were however declared without a question mark: Before C# 8, all reference types were nullable. String nonNullable = null // compiler warningīecause of the language history, the decision to use the same syntax for value types and reference types changes the behavior of the language for reference types. allowing a null value) or non-nullable (not allowing a null value): In C# 8, nullable reference types use the same syntax to give the option of declaring reference types as nullable (i.e. The int? notation is a shorthand for the Nullable generic type which wraps a value type to allow assigning a null value to it. Since the introduction of generics in C# 2, value types can be declared nullable or non-nullable: The feature was originally planned for C# 7 and was finally released as part of C# 8. Nullable reference types bring similar functionality to C#.
In Kotlin (preferred language for Android development), all types don’t allow null values by default.TypeScript has the strictNullChecks option.In recent years, there’s been a trend of strict null checking in programming languages: