C# Q & A


What are nullable reference types in C#?

Nullable reference types, introduced in C# 8.0 and further refined in later versions, are a powerful feature aimed at enhancing code safety and preventing null reference exceptions, a common source of runtime errors in C# applications. In traditional C#, reference types like classes are nullable by default, meaning they can hold a `null` value, which can lead to unexpected runtime errors when accessed. Nullable reference types introduce the idea of non-nullable and nullable reference types, making it explicit whether a reference type can hold a `null` value or not.

To use nullable reference types, you enable them at the project level by adding a `<Nullable>enable</Nullable>` or `<Nullable>warnings</Nullable>` setting in your project file. Once enabled, the compiler will analyze your code and issue warnings or errors when it detects potential nullability issues. 

Non-nullable reference types are denoted by adding a `!` after the type, for example, `string!`. These types are guaranteed not to be `null`. Nullable reference types are represented by the absence of the `!`, for example, `string?`, indicating that the value can be `null`.

Developers can leverage nullable reference types to write more robust and self-documenting code. They help catch null-related bugs at compile-time rather than runtime, improving code quality and reducing the likelihood of unexpected crashes. By making nullability explicit, nullable reference types encourage better code practices and contribute to the overall reliability and maintainability of C# applications.

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